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The effect of caffeine on the heart rate: The effects of caffeine on blood pressure and heart rate: A review


Ask an Expert: How does caffeine affect the heart?

Q: “How do different kinds of caffeine (coffee, tea, soft drinks, energy drinks) affect the cardiovascular system?”

Answer from Ty Gluckman, M.D., cardiologist, Providence St. Vincent Heart Clinic – Cardiology:

Many studies have looked at the effects of coffee, and some have looked at the effects of tea and soft drinks (energy drinks, which are newer, have not been studied as much). None of these studies has offered any evidence to suggest that different sources of caffeine affect us in different ways.

Based on the data that we have, the effects of caffeine on the cardiovascular system appear to be mild, short term, and related more to the quantity rather than the source of the caffeine.

In general, caffeine affects the cardiovascular system in several ways:

  • In people who don’t consume caffeine very often, it can cause systolic blood pressure (the top number in your blood pressure reading) to rise in the short term by as much as 10 points. In habitual caffeine consumers, this effect is much less pronounced.
  • Caffeine can act on enzymes in the heart that stimulate the intensity of the heart’s contractions.
  • Caffeine can facilitate the release of natural hormones that act on the heart to release norepinephrine, which can produce a stimulated effect similar to that of adrenaline.
  • At higher levels, caffeine can increase the amount of calcium inside the cells in the heart. Since all of the cells involved in the heart’s squeezing and relaxing are regulated by calcium, an increase can affect the heart’s pumping action.

For some people, these biologic effects cause no symptoms at all. Others may feel like their heart is pounding, racing or beating irregularly. But despite these short-term biologic effects, no study has demonstrated any appreciable harm or long-term problems caused by caffeine. This is true both for people who are perfectly healthy and for people who have been diagnosed with cardiovascular disease.

Two large epidemiological studies observed people over time to determine whether there was a relationship between consumption of caffeine (the studies looked at coffee, tea and soft drinks, but not energy drinks) and the development of heart disease, cardiovascular disease or cerebrovascular disease. Neither the Health Professionals Study nor the Nurses Health Study was able to demonstrate any relationship between caffeine consumption and increased risk.

Studies done in people diagnosed with cardiovascular disease also have failed to demonstrate a definitive effect. Nonetheless, because caffeine is a stimulant, people who have abnormal heart conditions or high blood pressure should discuss caffeine intake with their physician.

The stimulant effects of caffeine have raised concerns about the potential for causing abnormal heart rhythms. However, although caffeine can cause short-term effects that mimic the symptoms of a heart rhythm abnormality, very detailed, well-done studies have failed to demonstrate that it can actually cause a rhythm disorder.

One small study done in Costa Rica did suggest that genetic makeup may predispose some people to higher cardiovascular risk when they accumulate caffeine at very high levels. This study looked at how we metabolize caffeine. It found that abnormalities in the enzymes that metabolize caffeine can lead some people to metabolize caffeine very slowly, allowing it to build up in their systems. In these “slow metabolizers,” high accumulations of caffeine may pose a higher risk for adverse cardiovascular effects.

Consuming very high doses of caffeine is generally not recommended for anyone. Doses of 500 mg or more can cause “caffeine intoxication,” a diagnosis listed in both the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV) and in the International Classification of Diseases and Related Health Problems (ICD-10). Symptoms may include anxiety, panic attacks, elevated blood pressure, increased gastric acid, bowel irritability and insomnia, depending on an individual’s tolerance to caffeine. These symptoms usually go away as soon as the caffeine leaves the system, however, and there are no lasting consequences.

For people who are heavily dependent on caffeine, the absence of caffeine can cause problems, as well. Withdrawal can cause sweating, headaches, fatigue and other unpleasant symptoms.

In general, however, the preponderance of evidence does not suggest any lasting, harmful cardiovascular effects related to caffeine.

Dr. Gluckman’s clinic location

Providence St. Vincent Heart Clinic – Cardiology
9427 SW Barnes Road, Suite 498
Portland, OR 97225

July 2010

The effects of varying doses of caffeine on cardiac parasympathetic reactivation following an acute bout of anaerobic exercise in recreational athletes | Journal of the International Society of Sports Nutrition

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  • Caffeine and Heart Rate: What Is the Effect of Caffeine on Heart Rate? | Science project

    What effect does caffeine have on human heart rate?

    • 10 Adults or more (We want to test as many as possible. Why do you think this is?)
    • Mp3 player loaded with relaxing music
    • Clock and stopwatch (a cell phone usually has both of these functions)
    • Eye mask
    • 5 cans of a caffeinated version of a drink
    • 5 cans of a non-caffeinated version of the same drink
    • Paper and tape
    • Notebook
    1. Spend some time learning how to accurately take a person’s pulse. There are plenty of good resources online that can teach you how. Using a stopwatch, make sure to practice taking somebody else’s pulse until you’re sure you can get an accurate reading every time.
    1. Mask your drinks using your paper and tape and label each can with a number.
    2. Make sure that you record whether each number is caffeinated or non-caffeinated in your notebook.
    3. Arrange a time to test each adult. It will take around 30 minutes to perform the test. Test each person at around the same time of day, in the same circumstances (same chair, same song, etc.). Be sure to test each adult one at a time. Ask each person to refrain from eating or drinking for two hours before the test. Why do you think we want to make sure all of these things are the same from one test to the next?
    4. Ask each subject what his or her caffeine consumption habits are. Record the subject’s answers on a sheet of paper dedicated to that subject, and be sure to keep your records confidential.
    5. Have your subject put the mask over his or her eyes. Have the subject put the headphones on, listen to the music, and relax.
    6. After five minutes have passed, take and record your subject’s starting pulse without disturbing them.
    7. Provide your subject with a randomly selected drink. Record the drink’s number in your notebook. Ask your subject to drink it as quickly as possible.
    8. Wait five minutes, and then take and record your subject’s pulse. Continue taking the subject’s pulse at 5-minute intervals until 15 minutes have passed.
    9. Graph the data you recorded.
    10. Do people who consume caffeine regularly react to the caffeine? To the placebo? To both? Is there a correlation between habitual caffeine consumption and the change in pulse rate? Try to think of as many questions as you can, and keep an eye out for surprising results. After you are satisfied with your analysis, look up the effects of caffeine on the body and see if your study agrees with what other scientists have found.

    The results you get will depend strongly on what subjects you used for your study.

    Caffeine is a stimulant, a class of drugs that increase your heart rate and make you more energetic. However, the effects of caffeine are not identical between subjects. Plenty of people are born with a natural tolerance to caffeine, meaning that the caffeine’s effects aren’t so pronounced when such people consume it. People without a natural tolerance may also develop one over time simply by drinking caffeine.

    The possibility that certain people may have a tolerance to caffeine while others may not is one example of a variable—something that has a direct influence on the information we gather. Here’s an example of how this variable might work: you may find yourself testing two people that just happen to be naturally very tolerant to caffeine. If these happened to be the only two people you tested, you may not have seen a significant change in heart rate.  This data may have led you to a misleading conclusion about caffeine’s effect on the human body! This is why you were instructed to test as many subjects as possible and why you were told to ask your subjects about their caffeine habits. When you take these steps, you can collect more useful data that lets you control the variable of tolerance by identifying the people that are more likely to have a similar tolerance to the drug.


    1. This effect applies to the researchers, too. If researchers know they’re administering a drug as opposed to a placebo, there’s a chance they may look extra carefully for signs that the drug is doing something. This introduces bias into the experiment and can distort the results! A Double-Blind Study is one in which even the people administering the test don’t know what option they’re testing. This helps prevent bias from affecting the study’s results.

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    Caffeine Consumption and Heart Rate and Blood Pressure Response to Regadenoson



    Current guidelines recommend that caffeinated products should be avoided for at least 12 hours prior to regadenoson administration. We intended to examine the effect of caffeine consumption and of timing of last dose on hemodynamic effects after regadenoson administration for cardiac stress testing.


    332 subjects undergoing regadenoson stress testing were enrolled. Baseline characteristics, habits of coffee/caffeine exposure, baseline vital signs and change in heart rate, blood pressure, percent of maximal predicted heart rate, and percent change in heart rate were prospectively collected.


    Non-coffee drinkers (group 1) (73 subjects) and subjects who last drank coffee >24 hours (group 3) (139 subjects) prior to regadenoson did not demonstrate any difference in systolic blood pressure, heart rate change, maximal predicted heart rate and percent change in heart rate. Systolic blood pressure change (15.2±17.1 vs. 7.2±10.2 mmHg, p = 0.001), heart rate change (32.2±14 vs. 27.3±9.6 bpm, p = 0.038) and maximal predicted heart rate (65.5±15.6 vs. 60.7±8.6%, p = 0.038) were significantly higher in non-coffee drinkers (group 1) compared to those who drank coffee 12–24 hours prior (group 2) (108 subjects). Subjects who drank coffee >24 hours prior (group 3) exhibited higher systolic blood pressure change (13±15.8 vs. 7±10.2, p = 0.007), and heart rate change (32.1±15.3 vs. 27.3±9.6, p = 0.017) as compared to those who drank coffee 12–24 hours prior to testing (group 2).


    Caffeine exposure 12–24 hours prior to regadenoson administration attenuates the vasoactive effects of regadenoson, as evidenced by a blunted rise in heart rate and systolic blood pressure. These results suggest that caffeine exposure within 24 hours may reduce the effects of regadenoson administered for vasodilatory cardiac stress testing.

    Citation: Bitar A, Mastouri R, Kreutz RP (2015) Caffeine Consumption and Heart Rate and Blood Pressure Response to Regadenoson. PLoS ONE 10(6):


    Editor: Claudio Borghi, University of Bologna, ITALY

    Received: February 12, 2015; Accepted: May 19, 2015; Published: June 22, 2015

    Copyright: © 2015 Bitar et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited

    Data Availability: Patient level data are available through the Indiana University School of Medicine Institutional Review Board for researchers who meet the criteria for access to confidential data.

    Funding: This publication was made possible in part, with support from the Indiana Clinical and Translational Sciences Institute funded, in part by Grant Number (U54-RR025761. Anantha Shekhar, PI) from the National Institutes of Health, National Center for Advancing Translational Sciences, Clinical and Translational Sciences Award, and the Indiana CTSI Specimen Storage Facility which was funded in part by a NCRR construction grant (C06-RR020128-01. R.S. Fife, PI, K. Cornetta, Co-I). The project was supported by the Indiana University Health Values Grant, the Indiana University Health – Indiana University School of Medicine Strategic Research Initiative, and the Methodist Research Institute Showalter Grant for Cardiovascular Research. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

    Competing interests: The authors declare that they have no competing interests.


    Myocardial perfusion imaging (MPI) has been extensively used for detecting coronary artery disease, assessing viable myocardium, and evaluating the effect of different therapeutic interventions [1]. Vasodilator stress testing accounts for up to 45% of MPI studies [2]. Adenosine and dipyridamole have been the main vasodilators used for stress testing until 2008 when regadenoson was approved by the FDA [3]. Regadenoson is a selective adenosine A2A receptor agonist. It has a very low affinity for A1 adenosine receptors and almost no affinity for A2B and A3 adenosine receptors. Regadenoson’s selectivity for A2A receptors results in increased vasodilation and subsequently increased coronary blood flow (CBF). It is administered at a fixed dose of 0.4mg as an intravenous bolus. It has a rapid onset of action and a short duration of action with maximal plasma concentration achieved within 1 to 4 minutes after administration and an initial half-life of 2 to 4 minutes. [4–6].

    The American Society of Nuclear cardiology recommends against the consumption of caffeinated food andbeverages or foods containing other methylxanthines (chocolate) for at least 12 hours prior to regadenoson administration (ASNC 2009). Caffeine, a (1,3,7-trimethylxanthine), is a non-selective competitive inhibitor of all adenosine receptors particularly A2A receptors [7,8].

    Few studies assessed the interaction of regadenoson and caffeine. In conscious dogs, intravenous administration of caffeine at 1–10 mg/kg, followed by regadenoson injection 45 minutes later, did not significantly affect regadenoson induced coronary blood flow (CBF), but reduced the duration of the 2-fold increase in CBF. It also blunted heart rate and blood pressure change [9]. In a randomized, placebo-controlled, double blind and crossover pilot study of healthy subjects, Gaemperli et al. showed that moderate caffeine intake 2 hours prior to regadenoson administration did not affect myocardial blood flow (MBF) and blood pressure response but resulted in a blunted heart rate response [10]. In contrast another randomized placebo controlled study demonstrated that administration of 200 or 400 mg of caffeine 90 minutes before regadenoson significantly reduced the number of segments with reversible defects by MPI [11].

    The effect and duration of caffeine exposure on blood pressure, heart rate, and percent of maximal predicted heart rate among subjects undergoing pharmacological stress testing with regadenoson is not clear. We hypothesized that chronic caffeine intake with only 12–24 hours cessation prior to regadenoson stress testing according to drug labeling recommendation, affects maximal heart rate and blood pressure response as compared to non-caffeine consumption or more prolonged interruption. The aim of the current study is to assess the effect of habitual caffeine consumption on blood pressure, heart rate, percentage of predicted heart rate and percentage change in heart rate among subjects undergoing vasodilator stress testing with regadenoson.



    The study protocol was approved by the Indiana University institutional review board for research. Written informed consent was obtained from all subjects. Subjects referred for regadenoson stress testing were enrolled. Patients with combined exercise and regadenoson stress testing were excluded from analysis. As per the protocol of our institution, all patients were asked to not consume caffeinated beverages or xanthine containing foods for at least 12 hours prior to study. Moreover, all patients were asked to take their routine daily medications. Baseline demographic data and medical comorbidities were collected on all subjects. Information on amount, frequency, and last exposure to caffeine, chocolate, and caffeinated soft drinks were collected prospectively prior to performance of cardiac stress test. Caffeine exposure was classified according to none recently, last exposure of at least one cup of coffee 12–24 hours prior to regadenoson stress test, and >24 hours prior to stress test. Consumption of one cup of black or green tea was considered equal to one cup of coffee, and subjects who consumed tea were included in the coffee consumption group for analysis. Subjects’ heart rate (HR), and blood pressure were recorded at baseline instantaneously before administration of regadenoson. Subjects remained in a supine position throughout the test. Change in heart rate (changeHR) during the stress test was calculated by subtracting resting (restingHR) from peak heart rate (peakHR) recorded within 5 minutes after administration of regadenoson. Change in systolic blood pressure (changeSBP) was calculated by subtracting resting (restingSBP) from peak systolic blood pressure (peakSBP) recorded within 5 minutes after administration of regadenoson. Maximal predicted heart (MHR) rate was calculated using 220-age (years) and percent maximal predicted heart rate (%MPHR) was calculated by peakHR over MHR and multiplying by 100 (%MPHR = (peakHR/MHR)*100). Percent change in heart rate (%ChangeHR) was calculated by changeHR over restingHR and multiplying by 100. Incidence of patient reported side effects were prospectively recorded (dyspnea, nausea, flushing, dizziness, abdominal pain, headache, chest pain).

    Non-coffee drinkers (group 1) were compared to subjects who had consumed coffee within 12 to 24 hours (group 2) or more than 24 hours (group 3) prior to regadenoson administration.

    Statistical Analysis

    Baseline demographic and clinical variables are descriptively summarized. Continuous variables are expressed as mean ± SD. Categorical data are presented as percent frequency. Unpaired two-sided Student’s t-test was used to compare normally distributed continuous data between two groups. One-way analysis of variance test (ANOVA) and post hoc Tukey comparisons were used to determine difference between different groups based on coffee consumption. Categorical variables were compared using the χ2 test and continuous variables were computed using student t test. Statistical significance was defined as p-value < 0.05.

    Multivariable linear regression with change in systolic blood pressure (SBP), HR, and percent maximal predicted heart rate achieved at peak exercise as outcome variables was performed for non-coffee drinkers, subjects exposed to coffee 12 to 24 hours and more than 24 hours before regadenoson administration. Exposure to coffee 12 to 24 hours prior was used as the reference category. Adjustment for known confounders was based on clinical variables known to affect caffeine metabolism, as well as clinical variables with p<0.1 in univariable analysis and if adjustment for the variables resulted in at least a 10% change in the estimate of the overall association.


    Baseline characteristics of the study subjects are described in (Table 1). Subjects mean age was 60±11 years. Among the subjects, 257 (78%) were coffee drinkers while 73 subjects denied any coffee consumption. Non-coffee drinkers tended to be younger (57.2±10.5 vs. 60.9±10.5 years, p = 0.01), more obese (105.7±30.7 vs.97.3±23.5 Kg., p = 0.014), consumed less chocolate (69.9% vs. 80.9%, p = 0.042), had more GERD (41.1% vs. 28.4%, p = 0.039) and were less frequently prescribed antiplatelet medication (37% vs. 52.9%, p = 0.016) as compared to coffee consumers. Twelve coffee drinkers did not report when they last consumed coffee. None of the subjects was taking theophylline. Table 1 summarizes baseline characteristics between non-coffee drinkers (group 1), subjects who drank coffee 12–24 hours prior (group 2) and those who drank coffee more than 24 hours to stress testing (group 3).

    SBP change (15.2±17.1 vs. 7.2±10.2 mmHg, p = 0.001), HR change (32.2±14 vs. 27.3±9.6 bpm, p = 0.038) and %MPHR (65.5±15.6 vs. 60.7±8.6%, p = 0.038) were significantly higher in non-coffee drinkers (group 1) compared to those who drank coffee 12–24 hours prior (group 2). %Change HR (44.8±19.7 vs. 40.7±15.76%, p = 0.377) was not significantly different between group 1 and 2.

    There was no significant difference in SBP change (15.2±17.1 vs. 13.01±15.8 mmHg, p = NS), HR change (32.2±14 vs. 32.1±15.3 bpm, p = NS), %MPHR (65.5±15.6 vs. 64.3±13.6%, p = NS), and %Change HR (44.8±19.7 vs. 46.8±23.7%, p = NS) between non-coffee drinkers (group 1) and those who drank coffee >24 hours prior (group 3). Moreover, subjects who drank coffee >24 hours prior (group 3) exhibited higher SBP change (13±15.8 vs. 7±10.2, p = 0.007) and HR change (32.1±15.3 vs. 27.3±9.6, p = 0.017) as compared to those who drank coffee 12–24 hours prior to testing (group 2). MPHR (64.3±13.6 vs. 60.7±8.6%, p = 0.077) and %Change HR (46.82±23.7 vs. 40.7±15.76%, p = 0.053) were higher among group 3 compared to group 2 but failed to achieve statistical significance (Table 2) (Fig 1).

    Fig 1. Regadenoson Effect on SBP change, HR change, %MPHR and % changeHR According to Coffee Consumption.

    Group 1: non-coffee drinkers; Group 2: subjects who drank coffee 12–24 hours prior to stress test; Group 3: subjects who drank coffee more than 24 hours prior to stress test. Error bars correspond to 95% confidence interval.


    After adjusting for age, race, weight, chocolate consumption, diuretics use, history of coronary artery disease, past myocardial infarction, asthma, calcium channel blocker and beta blocker use, Change SBP (p = 0.003), Change in HR (p = 0.046) and %MPHR (p = 0.015) remained significantly different between non-coffee drinkers (group 1) and subjects who consumed coffee 12–24 hours prior (group 2) in multivariable regression analysis. Moreover, on multivariable regression analysis, Change SBP (p = 0.031), Change HR (p = 0.019), and %Change HR (p = 0.041) remained significantly different between subjects who drank coffee 12–24 hours (group 2) and subjects who drank coffee more than 24 hours prior.

    Among subjects who drank coffee 12–24 hours (group 2) prior to regadenoson administration, the number of coffee drinks did not have any effect on Change HR, Change SBP, MPHR and %Change HR (Table 3).

    The number of self-reported adverse effects was lower in subjects exposed to caffeine 12–24 hours prior to regadenoson (group 2), as compared to >24 hours prior (group 3, or caffeine naïve subjects (group 1)(1.35±1.1 vs. 1.94±1.4 vs. 1.79±1.4; p = 0.002). Group 2 developed less abdominal pain (0.9% vs 16.4% vs. 14.4%, p<0.001), nausea (12% vs. 28.8% vs. 26.6%, p = 0.007) and dizziness (17.6% vs. 32.9% vs. 38.1%, p = 0.002) when compared to groups 1 and 3.


    In our study, subjects who were coffee naive (group 1) or those who consumed coffee more than 24 hours prior (group 3) demonstrated significantly larger change in heart rate and systolic blood pressure when compared to subjects exposed to coffee within 12–24 hours (group 2) prior to regadenoson exposure.

    The blunted rise in heart rate and systolic blood pressure observed in subjects with recent exposure to caffeine may be attributed to the long caffeine half-life in some patients. Caffeine (1,3,7-trimethylxanthine) bioavailability is 100%, with peak level achieved within 15 to 45 minutes [12]. It is metabolized predominantly by cytochrome P450 (CYP1A2 isoenzyme) with a half live (t1/2) ranging between 2 to 12 hours [12,13]. Many conditions and medications have been reported to affect caffeine metabolism and potentially affect its half-life. CYP450 inhibitors such as cimetidine, oral contraceptive usage, pregnancy, and alcoholic liver disease can increase caffeine half-life [14–16]. CYP450 inducers, such as phenytoin, phenobarbital, or rifampin, as well as smoking have been associated with a shortened caffeine half-life [17–18]. Caffeine is metabolized into 3 active metabolites: paraxanthine (1,7-dimethylxanthine), theobromine (3,7-dimethylxanthine) and theophylline (1,3-dimethylxatnhine)[19]. In humans, these metabolites account for 84%, 12% and 12% of caffeine metabolism respectively [20]. The half-life of paraxanthine, theobromine and theophylline can be as high as 4, 7 and 6 hours respectively, and these active metabolites can therefore extend the biologic effects of caffeine exposure [21].

    Caffeine is a competitive inhibitor of adenosine A1, A2A and A2B receptors [22]. Chronic inhibition of adenosine receptors by caffeine results in increased sensitivity and up-regulation of those receptors [23,24]. Selective A2A receptors agonists, like regadenoson, are believed to increase heart rate by a reflex increase in sympathetic activity triggered by their vasodilatory effect on peripheral A2A receptors [25]. However, more recent evidence indicates a chemoreceptor mediated activation of the sympathetic nervous system and release of catecholamines [26,27]. In the coronary circulation, there is a high reserve for A2A receptor mediated coronary vasodilation with 25% receptor occupancy by regadenoson translating into 90% maximal vasodilation [10,28]. Thus minimal competitive inhibition by caffeine has been thought not to significantly impact maximal myocardial blood flow. In contrast, in the peripheral vasculature, A2A receptor reserve may be lower, thus possibly explaining a blunted increase in heart rate in response to regadenoson in subjects exposed to caffeine [10]

    In addition, A2A receptors are present in the atrium and are able to activate ryanodine receptors [29]. Ryanodine receptor activation and subsequent calcium release mediates beta adrenergic heart rate stimulation [30]. A2A receptor agonists have been shown to modulate the response to beta adrenergic stimulation by attenuating the effect of A1 receptor and increasing contractility directly [31]. Therefore it is possible that caffeine exposure and partial inhibition of A2A receptors leads to decreased ryanodine receptor activation and blunting of beta adrenergic response mediated by A1 receptor. Our study findings suggest that consumption of caffeine within 24 hours may inhibit the vasodilatory properties of regadenoson administered for MPI. Moreover altered heart rate and blood pressure response could have been in response to a combination of altered sympathetic tone, variable chemoreceptor response, and vasodilatory effects by caffeine and regadenoson. We observed a decreased incidence of patient reported side effects in subjects exposed to caffeine between 12–24 hours supporting the possibility that residual caffeine activity attenuates the biologic response to regadenoson within this time window. It has been previously demonstrated that caffeine administered in doses of 200 or 400mg 90 minutes before regadenoson significantly reduces the sensitivity of MPI [11]. Following caffeine administration the mean number of reversible defects identified was reduced by approximately 60% [11]. It is therefore possible that based on variations in caffeine metabolism, exposure to caffeine between 12–24 hours before regadenoson could also reduce the sensitivity of regadenoson MPI. It may be necessary to hold caffeine consumption for 24 hours prior to regadenoson MPI to avoid any residual interaction.

    Our study had many limitations. First, we did not measure blood caffeine level and thus we did not assess the association between serum caffeine level and effect on HR, BP and %MPHR response. Second, patient recall bias of caffeine consumption might have contributed to our results. We could not control for the potential possibility of patients underreporting their caffeine consumption in order to avoid stress test delay or cancelation. Altered sympathetic tone, variable chemoreceptor response, as well as vasodilatory effects by caffeine and regadenoson could have contributed to changes in heart rate and blood pressure response. Moreover, it is difficult to assess variations in caffeine dosing based on beverage types.


    Caffeine exposure within 12–24 hours prior to regadenoson MPI seems to attenuate the hemodynamic effect of regadenoson as indicated by blunting of heart rate and systolic blood pressure rise. Further studies are needed to examine the possible impact of caffeine exposure within 12–24 hours as currently endorsed in the FDA label on diagnostic sensitivity and specificity of regadenoson stress imaging.


    This publication was made possible in part, with support from the Indiana Clinical and Translational Sciences Institute funded, in part by Grant Number (U54-RR025761. Anantha Shekhar, PI) from the National Institutes of Health, National Center for Advancing Translational Sciences, Clinical and Translational Sciences Award, and the Indiana CTSI Specimen Storage Facility which was funded in part by a NCRR construction grant (C06-RR020128-01. R.S. Fife, PI, K. Cornetta, Co-I). The project was supported by the Indiana University Health Values Grant, the Indiana University Health–Indiana University School of Medicine Strategic Research Initiative, and the Methodist Research Institute Showalter Grant for Cardiovascular Research.

    Author Contributions

    Conceived and designed the experiments: AB RK RM. Performed the experiments: RK RM AB. Analyzed the data: RK RM AB. Contributed reagents/materials/analysis tools: RK RM AB. Wrote the paper: RK RM AB.


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    How Caffeine Effects Heart Rate


    Background Information: The human heart is a major muscular organ located in the thoracic cavity between the lungs. Its major function is to pump blood throughout the body. A double-layered sac, Pericardium, which is the tough connective tissue protects and anchors the heart. There is fluid between the layer of the sac allow for lubrication of the heart’s continual motions. The inner layer of the sac is the heart wall, which is mainly cardiac muscle. The human heart is made up of two chambers. The atriums receive blood from veins, and the ventricles pump blood into the arteries. For the blood to pass through the an atrium to a ventricle for example, the blood has to pass through a heart valve. Valves control the blood from moving backwards. The “lub-dub” sound made by a beating heart derives from the closing of the atrioventricular (AV) valves, then the concurrent closing of the aortic and pulmonary valves (Starr, 2007). The human heart is also myogenic meaning the heart is independent of an outside stimulus from the nervous system. The sinoatrial (SA) node, pace maker, is responsible for sending electrical impulses through the heart making it contract and pump blood. The human heart is very much affected by the consumption of caffeine. Caffeine can be found in certain coffees, teas, sodas, and chocolates. By consuming caffeine one’s heart rate to dramatically increase and also cause abnormal heart rhythms (Medline Plus: Caffeine, 2012).

    Problem Question: What is the effect of caffeine from coffee, herbal tea, and black tea on heart rate?

    Hypothesis: If a human consumes a beverage containing a higher concentration of caffeine, then the heart rate will be higher than consuming a beverage with a lower concentration of caffeine.

    Hypothesis Explanation: This is because caffeine is a stimulant. Stimulants change the way the brain works by changing the way nerve cells communicate. Nerve cells, called neurons, send messages to each other by releasing chemicals called neurotransmitters. Neurotransmitters work by attaching to key sites on neurons called receptors. Stimulants can also cause the body’s blood vessels to narrow, constricting the flow of blood, which forces the heart to work harder to pump blood through the body. The heart may work so hard that it temporarily loses its natural rhythm (Stimulants, 2012). A normal resting heart rate for adult’s ranges from 60 to 100 beats a minute. In most cases, a lower heart rate at rest implies more efficient heart function and better cardiovascular fitness. For example, a well-trained athlete might have a normal resting heart rate closer to 40 beats a minute (Caffeine content for coffee, tea, soda and more, 2011). Additionally caffeine blocks the enzyme phosphodiesterace, which normally activates production of an enzyme, cyclic AMP (cAMP), this initates a protein that increases heart rate. The heart rate is regulated as cAMP is kept in a drug free cell. When caffeine is introduced, cAMP is eliminated, placing the protein (PKA) into overdrive. Therefore, heart rate is increased when caffeine is consumed (Caffeine Pharmacology, 2012). Nonetheless a beverage with more caffeine will lead to a greater amount of heart rate in beats per minute (bpm±1.0bpm) as compared to a beverage with less caffeine.


    Dependent: Number of heart pulse rate in beats per minute (bpm±1.0bpm). This measurement will be taken by placing the index and middle finger on the neck pressing gently on the carotid artery, ten minutes after the consumption of either caffeinated coffee, herbal tea, or black tea, and counting the heart rate over the course of one minute.

    Independent: Amount of caffeine found in 250ml of either caffeinated coffee, herbal tea or black tea.


    Table 1. Controlled variables kept constant

    illustration not visible in this excerpt

    Experimental Control: The experimental control is the number of heart pulse rate in beats per minute (bpm±1.0bpm) after an hour of physical rest. The experimental variables do not effect the experimental control. The experimental control is to be used in comparison against other trials with physical activity.


    Can Caffeine Cause Irregular Heart Rhythms?

    New research challenges age-old assumptions about caffeine.

    If you’re a coffee drinker, you may be concerned about how your daily cup (or two) of joe is affecting your heart health.

    Because caffeine is a stimulant, you might think it puts stress on your ticker, especially if you are prone to irregular heart rhythms called arrhythmias. For a long time, doctors didn’t think coffee was heart-healthy, either. But times (and research) are changing.

    Caffeine’s impact on arrhythmias

    Some research has looked specifically at the effects of caffeine on irregular heart rhythms. One study found that the instances of arrhythmia were no different among caffeine consumers (specifically coffee, tea and chocolate) and those who didn’t consume caffeine.

    In a small Brazilian study, participants with heart problems were randomly assigned to drink a caffeinated or decaffeinated drink, then assessed with electrocardiograms and stress tests. Researchers found no difference in irregular heart rhythms between the two groups.

    So what’s the bottom line on coffee’s role in heart health, specifically irregular heart rhythms?

    “The available research suggests that caffeine in doses typically consumed, about 400 mg a day or about five cups of coffee, does not provoke arrhythmias,” says Helga Van Herle, MD, MS, a cardiologist at Keck Medicine of USC and associate professor of clinical medicine at the Keck School of Medicine of USC.

    Coffee’s impact on your overall heart health

    Recent research, including a study from the University of Southern California, has found an association between coffee drinking and longevity. Studies have also shown less cardiovascular disease among people who drink coffee, making coffee actually heart-healthy.

    But what about caffeine’s role in all this? While many studies find benefits in coffee, many of those benefits occurred whether the coffee was caffeinated or decaffeinated. It’s possible that there could be something else in coffee that boosts health. Or, it could be that there is another confounding factor affecting the results — after all, these studies have only proved a link, not a cause and effect.

    Research presented at an American Heart Association conference, though, provided a mechanism for how caffeine itself might improve heart health. Drinking a cup of coffee significantly improved blood flow among small blood vessels, which may keep your heart from having to work too hard.

    See how caffeine makes you feel

    Although the research doesn’t currently support a link between caffeine and arrhythmias, if you find caffeine seems to worsen the condition, consider cutting down.

    “There are patients who may be sensitive to caffeine and note the onset of palpitations or worsening palpitations with low or any caffeine intake,” Van Herle says. “I usually advise my patients with palpitations that are worsened with caffeine to cut down if they can and reassure others with arrhythmias, that are not affected by caffeine, that they can continue to use it in moderate amounts.”

    But there might be one exception to the caffeine rule for heart health. “In general I do advise my patients to stay away from ‘high energy’ drinks that contain very high caffeine content,” Van Herle adds.

    Irregular heartbeat, which can feel like a fluttering or racing heart, is a cause for concern because it may mean your heart isn’t working properly. It can be a sign of heart disease, including coronary artery disease or cardiomyopathy (problems with the heart muscle). But, according to the American Heart Association, most arrhythmias are actually harmless. Only a doctor can tell for sure, so report an arrhythmia to your health care professional if you experience it.

    by Tina Donvito

    Have you experienced an irregular heartbeat? Our heart specialists can help. If you are in the Los Angeles area, request an appointment or call (800) USC-CARE (800-872-2273).



    Sixteen men in the third, sixth, seventh and eighth decades of life received coffee or caffeine plus decaffeinated coffee on one or two days of each week and decaffeinated coffee on the intervening days for a period of from three to fourteen weeks.

    Decaffeinated coffee did not affect reaction time, i.e., the response remained uniform from day to day and did not change when the size of the dose was varied. Coffee or caffeine in dosages equal to or exceeding 2 mgm. of caffeine per kgm. of body weight altered reaction time, each dose frequently exerting an influence for twenty-four hours. With doses equivalent to 3 or 4 mgm. of caffeine per kilogram the reaction time ¼ to 3¼ hours after the drugs was from 2 to 6 per cent shorter than that after decaffeinated coffee, but on the day following the dose it was frequently longer. The response did not change throughout one or two months of experimentation and was essentially the same in the elderly men as in the young men. With doses equivalent to 2 mgm. of caffeine per kilogram the reaction time was shorter than that after decaffeinated coffee in certain individuals and longer in others. The variability (standard deviation of the average reaction time) after coffee or caffeine was generally not as great as that after decaffeinated coffee.

    One or two hours after coffee (doses equivalent to 3, 4 or 4.5 mgm. of caffeine per kilogram) the blood pressure was higher (5 to 10 mm. Hg) and the pulse rate, slower (5 per minute) in certain individuals and faster in others than the blood pressure and the pulse rate after decaffeinated coffee. The changes in blood pressure and pulse rate elicited by coffee were more distinct in the older men than in some of the young men.


      • Received December 26, 1934.

    Research paper “The effect of coffee on the cardiovascular system”


    Research work

    Coffee and its effect on the cardiovascular system

    Completed the work: Nikiforova Yana Mikhailovna, student of the 9th grade


    9000 Kamashina Kamashina Teacher Sergeevna



    It has long been proven that proper nutrition is the key to good health and well-being in general.If a person does not adhere to the correct diet, he experiences weakness, constant overwork, is unable to resist diseases, and has slow thinking. But what kind of nutrition can be called correct? We all know that breakfast is the key to good health, so where does our breakfast begin?

    Nowadays it is difficult to find a person who would not love and drink such a well-known drink as coffee. It is considered especially popular in the morning hours, when a person needs to gain strength and vigor before the working day.A true lover will not limit himself to one cup in the morning, but will allow himself to miss a cup – another also during the day.

    Coffee is attractive to many because it can increase mental and physical activity of a person. In addition, coffee affects the mental state of a person and improves mood.

    However, not everyone has information about the effects of coffee on human health.

    On the one hand, coffee has entered people’s lives, it invigorates, lifts the mood – it is simply a favorite drink of millions of people.On the other hand, doctors often warn about the inadmissibility of consuming coffee in large quantities, as this will negatively affect the nervous system, cause insomnia, and gradually deplete nerve cells. The person becomes lethargic, drowsy and gets tired quickly. Thus, the problem of the impact of coffee on the human body and determining its benefits and harms is relevant.

    Purpose of the study: to identify how coffee affects the cardiovascular system by measuring heart rate and blood pressure

    Research objectives:

    1.analyze the literature on coffee and its effect on the human body.

    2. To reveal the attitude of respondents to coffee.

    3. Conduct experimental studies to identify the effect of coffee on the human cardiovascular system.

    Subject of research: coffee JACOBS MONARCH

    Subject of research: the effect of coffee on the human condition.

      1. From the history of coffee

    The history of coffee begins with the legend of an Ethiopian shepherd who drove goats over a pass.One day the shepherd was amazed at the strange agility of his goats. After observing the animals, he noticed that they begin to “dance” every time after they have gorged on the leaves and fruits of the tall shrub growing on the mountainside.

    The abbot of the local monastery living nearby was surprised, in turn, by the observations of the shepherd and gave his monks a decoction of coffee fruits and leaves. There is a legend about a hermit sheikh who treated the sick with a decoction of coffee fruits. And he treated so successfully that he was known as a saint in the district.They tell about warriors and travelers who took coffee beans with them to distant lands. Chewing green kernels was healthy, but very tasteless, and over time, someone figured to fry them, and then grind and boil them. From this momentous moment, coffee triumphantly marches through the world .

    The coffee tree came to other countries from Ethiopia – the province from which this tree comes from is called Kafa. Coffee leaves and grains were used for food by Ethiopians long before it became known to Europeans.Ethiopians added grains to food, as they noticed their invigorating effect.

    Coffee has played an important role in many societies throughout history.

    Muslims used coffee instead of church wine, drinking it during prayers. In Mecca, already in the 15th century, the first coffee houses appeared, in which pilgrims could relax. But soon men began to gather in coffee houses quite often, after which the mullahs banned coffee houses and the use of coffee, most likely, the reason for the persecution was that believers began to give clear preference to leisurely conversations over a cup of coffee, rather than offering prayers to Allah.The ban did not last long; Muslims became too addicted to coffee.

    Coffee appeared in Europe in the first half of the 16th century and became no less popular than in Muslim countries. European clergy also tried to combat its influence by imposing bans under the pretext that coffee, called “black blood of the Turks” and “soot syrup”. [2]

    The most enterprising of all were the Dutch, already at the beginning of the eighteenth century, who had coffee plantations on the island of Java.On the island of Martinique, there is a monument to the French captain de Kiel, who personally brought coffee trees.

    Russia recognized coffee later than Europe. True, Tsar Alexei Mikhailovich drank it, to whom the court physician prescribed “boiled coffee, known by the Persians and Turks” as a medicine against “arrogance, runny nose and headache.” Tsar Peter 1 was already intensively introducing coffee, captivated, as usual, by foreign innovation. [4]

    Coffee is an important export commodity: in 2004, coffee was the main agricultural export for 12 countries.

    Russia is one of the ten most coffee-consuming countries in the world

    Coffee or Coffee (Coffea L.) is a genus of plants from the madder family.

    Shrubs or small, often multi-stemmed, evergreen trees with opposite oval, pointed ends, shiny dark green, slightly wavy leaves.

    Leaves arranged in pairs, opposite or three, leathery, perennial or herbaceous, whole, with stipules.

    Flowers in the corners of the leaves, sitting in clusters, rarely single, white, bisexual, often fragrant (with the scent of jasmine). The number of parts in the calyx and corolla ranges from 4 to 9, but for the most part 5. The corolla is congenial with a short or long tube. The ovary is whole, round or nearly cylindrical, 2-nested, contains 1 ovule in each nest; the column is divided into 2-filamentous stigmas. Pollinated by wind or insects, sometimes self-pollination in the bud is possible.

    The snow-white flowers of the coffee tree smell nice and look like real jasmine flowers.The flowering of the coffee tree begins in the dry season and lasts until the first rains

    The fruit is a fleshy berry with 2-3 hard seeds, initially green, then yellowing and finally turning red.

    Plants are widely cultivated in many tropical countries for the sake of seeds – the so-called coffee beans, which give an aromatic drink – coffee. Coffee beans contain caffeine, thanks to which coffee has a tonic effect. Caffeine is also found in fruit pulp and leaves, but in much smaller quantities.

    Coffee beans are the seeds of the coffee berries, i.e. seeds of coffee trees. A coffee bean is surrounded by four shells: a dense, shiny outer skin of a dark red color, pulp, a hard capsule shell, which encloses both beans, and a thin silvery film covering each of two grains tightly pressed against each other

    In nature, about 40 species of coffee tree are found in the tropics of Africa and 33 species in Asia, mainly in mountain river valleys and forest edges.[2]

    The value of coffee is in the high content of alkaloids, especially caffeine. Because of him, an addiction to this drink arises. Also, coffee contains sugars, minerals, nitrogenous and other substances. One of the extremely rare in nature, chlorogenic, gives coffee a characteristic astringent flavor. Coffee contains trace elements that are necessary for the human body to function properly. Among them are found potassium, magnesium, calcium, sodium, iron, copper and strontium. And also traces of chromium, vanadium, barium, nickel, cobalt, lead, molybdenum, titanium and cadmium.

    Raw coffee has no aroma, has an astringent taste, does not boil well, therefore, before drinking coffee, it is roasted at t-2000C.

    Roasted coffee beans contains 14.4% fat, 13.9% nitrogenous substances, 13.9% minerals, 7% moisture, sugar, vitamins, 1.4% caffeine. The finest coffees contain no more than 1.5% caffeine in roasted beans, while medium-sized coffees contain up to 2%.

    The chemical composition of coffee indicates that it is not only a tasty product, but also has good nutritional benefits due to its fat, sugar and protein content.An important place in the chemical composition of coffee is occupied by the alkoloid caffeine, which has an exciting and stimulating effect on the human body.

    Many scientists rack their brains about the effect of coffee on the human body. According to some, coffee can cause irreparable harm to human health, according to others, it is a “magic drink” with healing properties . scientists from all over the world have conducted more than 19 thousand studies on the effects of coffee on health.And their results do not yet make it possible to objectively lean to one side or the other.

    Recent scientific studies unanimously repeat: “The benefits of coffee are undeniable!” The benefits of coffee, according to them, are so great that it is simply impossible to list all the positive effects.

    There is no doubt about the benefits of coffee as a means of improving mental and physical performance. Scientists have even proven the benefits of coffee for enhancing thinking ability through scientific experimentation.True, this applies only to those who are engaged in logical thinking.

    The mental health benefits of coffee are also reflected in the fact that it increases resistance to stress. It also reduces the risk of depression. Just 2 cups of coffee a day reduces the risk of liver, pancreas, colon and rectal cancer.

    The benefits of coffee are known for those who want to lose those extra pounds. Just 1 cup of coffee allows you to work out in the gym one third more intensely than usual.And in diets and sports, coffee forces the body to use not carbohydrates for energy, but only fat. And also the benefit of coffee for preserving youth and beauty lies in the fact that coffee contains antioxidants.

    The benefits of coffee have also manifested themselves in medicine. Caffeine is used as a therapy for diseases that depress the central nervous system. For example, in case of poisoning with drugs and poisons, infectious diseases, insufficiency of the cardiovascular system, vasospasm.Caffeine is one of the components of the following drugs: Askafen, Novomigrofen, Novocefalgin, Pyramine, Citramon, Kofetamin.

    But abuse of coffee can cause chronic poisoning of the body. Long-term consumption of coffee in large quantities leads to disorders of varying degrees, which together constitute the clinical picture of chronic intoxication, known as caffeism.

    However, there are proven facts about the dangers of coffee for the human body.

    In certain doses, coffee improves reaction, increases physical activity, brain excitability, mental and physical performance.

    However, the harm of coffee is that it is difficult to independently determine this very dose. After all, the effect of caffeine on each person is individual, and depends on the type of nervous system. And even a small and not very long-term excess of the individual dose leads to depletion of nerve cells, disruption of the normal functioning of the body.

    That is why coffee should never be given to children. The harm of coffee for children is enormous. Coffee disrupts the growth and development of a child.No one, even avid coffee drinkers, should drink it before bed. The last cup should be drunk at least a few hours before bedtime.

    It has been proven that coffee enhances heart activity, speeds up the pulse. It also increases blood pressure. Thus, the harm of coffee for people with arterial hypertension, coronary heart disease and other diseases of the cardiovascular system is visible. And also for those who are predisposed to these diseases.

    An interesting fact is that the harm of coffee to the cardiovascular system depends on the way coffee is prepared.Brewed coffee is much more harmful than a drink from coffee makers. [5]

    It is well established that coffee interferes with absorption and flushes calcium, magnesium, potassium, sodium and some other trace elements from the body. Therefore, if you like coffee, be sure to take vitamin complexes or eat more foods rich in the above microelements.

    The harm of coffee in this sense affects women more than men. Surprisingly, this is a scientific fact.If a woman drinks more than 4 cups of coffee a day, then she has a very high risk of developing osteoporosis.

    Coffee is addictive. And this is also a proven scientific fact. Exceeding his individual dose, a person forms an addiction in himself. Now he simply physically cannot refuse coffee, the body reacts with severe fatigue, drowsiness and even depression. But at the same time, over time, the effect of caffeine is weakened and in order to achieve the same effect, a person has to increase the dose of coffee he drinks.[1]

    Thus, coffee, with all its positive properties, can have a negative effect on the body for a person suffering from various kinds of diseases.

    Having analyzed the collected literature on the effect of coffee on the human body. We decided to experimentally find out how coffee actually affects blood pressure and pulse.

    For the study, we invited 11 people from the Sachkovichi secondary school, aged 16 to 55 (students in grades 9, 11, as well as teachers and school employees), of different sex, constantly drinking coffee and not lovers of this drink.

    Most of our subjects drink instant coffee, so for the study we took JACOBS MONARCH instant coffee. A mechanical tonometer, a watch with a second hand for counting the pulse, was used to measure blood pressure.

    In order to correctly measure blood pressure, we had to remember classes in biology of grade 8, we also turned to the Sachkovichi FAP for advice, where they told us about the effect of coffee on the human body and clarified the correctness of blood pressure measurement.

    Pulse (HR) was determined by palpation at the base of the 1st toe (radial artery). The subject’s hand should lie freely so that muscle and tendon tension does not interfere with palpation. At first, the pulse was measured on the radial artery on two arms, the difference in measurements was not observed, so we decided to limit ourselves to measurements on one arm. The pulse was measured for exactly 1 minute. Then, blood pressure is the pressure developed by blood in the arterial vessels of the body. Systolic pressure (upper), diastolic (lower) are the most important indicators of the state of the heart and blood vessels.Normal pressure in an adult is 120/80 mm. rt. Art., a teenager has an average of 110/70. [6]

    Blood pressure was determined using a mechanical tonometer.

    Put on the stethoscope. Place the stethoscope disc on the inside of the bend of the elbow. We quickly inject air into the cuff using a rubber bulb – so that the systolic pressure on the screen is 30-40 units higher than the previous indicator of the subject. We inject air quickly – if you do it too slowly, the tonometer may give incorrect results.Then we slowly release the air from the cuff. As soon as we heard the heartbeat, we remember the readings on the screen – this is the systolic pressure. We continue to release air from the cuff and listen to the heartbeat. When we stop hearing it, we remember where the arrow points on the screen. This is the diastolic pressure.

    Pressure and pulse were measured before taking a cup of strong coffee, then after 5 minutes, 10 minutes and 15 minutes. Work with each subject was carried out individually. (Appendix 1)

    Also, a survey was conducted on the topic of research among students and employees of the Sachkovichi secondary school, which was attended by 56 people, including the subjects.(Appendix 2)

    In the course of the study on the effect of coffee on changes in blood pressure and heart rate, it was shown that caffeine acts on each organism individually.

    The subjects were divided into two groups: boys and girls from 15 to 18 years old and women and men from 36 to 55 years old.

    The analysis of the obtained results is as follows: in the 1st group there is a slight increase in the measured parameters. So the heart rate changed by an average of 10 points. Systolic pressure changed by 10 mm.rt. Art., diastolic – by 10 mm Hg. Art. These parameters are within normal limits.

    In the 2nd group there is a slight increase in the measured parameters. Heart rate in people of mature age changed by 10 points. Systolic pressure – 6 mm Hg. Art., diastolic – by 7 mm Hg. Art.

    The values ​​of heart rate and blood pressure in people of mature age, after drinking coffee, crossed the normal limit.

    Coffee has no negative effect on a young healthy body.A slight increase in heart rate and blood pressure indicates the excitation of the nervous system and activates human activity.

    In the case of mature people, a large increase in heart rate and blood pressure occurs, which can be attributed to a negative effect. Therefore, they should limit their consumption of coffee to a minimum or refuse it.

    Having processed the survey data, we came to the following: most of the respondents drink 2-3 cups of coffee a day, this is a good indicator, since doctors recommend drinking no more than 2-3 cups of this “magic drink” during the day.They prefer to drink coffee in granules, as it is more convenient and saves time. But about whether coffee is useful or harmful, the respondents were divided almost equally and only 7 people (12%) could not answer the question.

    Black coffee is the most popular beverage in the world. In terms of sales, it even surpasses such a commodity as oil. Symphonies and poems were dedicated to this drink. The philosopher Voltaire drank 50 cups of coffee a day. Anna Akhmatova said about coffee: “Without the necessary – I can, but without luxury – I can’t! It’s easier without bread than without coffee! ” [1]

    Growing coffee is a very laborious process.The coffee tree belongs to the genus, the madder family – evergreen shrubs and small trees. Originally from the tropics and subtropics of Africa and Asia. It grows in regions with hot climates. More than 55 varieties of the coffee tree are known in the world. But only two types are of interest: Arabian coffee Congolese coffee from the fruits of which, respectively, Arabica and Robusta varieties are obtained.

    First of all, coffee is used as a flavoring stimulating drink. Two thirds of the world’s population drink coffee for these reasons.The stimulating, stimulating and reinforcing effect of coffee extends to many physiological manifestations of a person, especially during physical fatigue. Then the stimulating effect of coffee has an almost magical effect on the human body, giving it strength and vigor in a short time. The influence of coffee on the central nervous system, especially on its higher parts, is manifold. A coffee drink containing one of the most important plant alkaloids, caffeine, is an irritant that stimulates and normalizes the central nervous system.Physiologically, caffeine is recognized as an excellent tonic. It eliminates lethargy, drowsiness, apathy.

    The impact of coffee on health is a favorite topic of controversy between coffee lovers and haters. It has been going on since time immemorial and is unlikely to ever end. After all, both sides consider the effects of coffee on health, based on the results of scientific research. And their results so far do not make it possible to objectively lean on one side or the other. How can you determine what is the real effect of coffee on health? We think everything is individual here.

    The results of our research have shown that coffee does not have a negative effect on a young healthy body. A slight increase in heart rate and blood pressure indicates the excitation of the nervous system and activates human activity. In the case of mature people, there is a large increase in heart rate and blood pressure, which can be attributed to a negative effect.

    When considering the effects of coffee on health, approach this issue individually. That is, ask yourself the question: “What is the effect of coffee on my health?” And listen to your body.

    1. Gergova A. “I know the world (Cuisine of the peoples of the world)”, “Family Library” publishing house. 1999,

    2. Traitak D.I. Reading book on biology: Plants: For students in grades 6-7 / – M .: Education, 1996

    3. Coffee without pills. Magazine “Health” .2007, №11

    4. Kholmogorova G. Is coffee still harmful or useful? We drink black. Russian newspaper. 2008, No. 264

    5. Zhilina E.Coffee pros and cons. Vesta. 2009, no. 3.

    6. www.ru.wikipedia.org

    7. http://www.bestkofe.ru/

    Influence of caffeine on the human body

    In the course of research work on chemistry on the topic “Effects of caffeine on the human body” , the author conducted practical experiments with the help of which he sought to determine whether caffeine affects the heart rate and how dangerous its use can be to health.

    Job details:

    Chemistry Study Project on “The Effects of Caffeine on the Human Body” contains background material on the history of the discovery and distribution of coffee. The author gets acquainted with the general characteristics, chemical structure and properties of caffeine, determines how caffeine affects blood pressure and heart rate, establishes the permissible daily intake of caffeine for consumption.

    In an individual research project on chemistry on the topic “The effect of caffeine on the human body”, a 9th grade student examined what the chemical composition of caffeine looks like from a medical point of view, considered the options for the development of events in case of a caffeine overdose, studied the signs of mental disorder caused by the use of caffeine.The author of the project listed which drinks and how much caffeine is contained.

    Table of Contents

    1. History of the discovery and distribution of coffee.
    2. Chemical composition and role of caffeine in medicine.
    2.1 Caffeine overdose.
    2.2 Mental disorders caused by the use of caffeine.
    2.3 Daily value of coffee.
    2.4 Caffeine content of various beverages.
    3. Experiment with coffee.
    3.1 Description of the experiment.
    Sources Used


    Relevance to Research : Caffeine is a substance found naturally in the leaves, fruits and seeds of over 60 plant species.It is found in various foods and beverages such as coffee, tea, chocolate and some non-alcoholic (mainly energy) drinks.

    Objective : To determine if caffeine affects heart rate.

    Subject of research: products containing caffeine.

    Research objectives .

    1. To familiarize yourself with the general characteristics, chemical structure and properties of caffeine.
    2. Determine how caffeine affects blood pressure and heart rate.
    3. Summarize the research results and draw conclusions based on the results.

    Research methods:

    1. Theoretical: the study, analysis, comparison and synthesis of literary and other sources of information on the research topic.
    2. Experimental: Daily blood pressure measurement using a tonometer.

    Statistical data: statistical processing of results.

    Theoretical value: deepening knowledge about the general characteristics, chemical structure, properties of caffeine.

    Practical value : to experimentally establish the effect of caffeine on the human body

    History of the discovery and distribution of coffee

    Discovered and named “ caffeine ” in 1819 by the German chemist Ferdinand Runge. In 1827 Udry isolated a new alkaloid from tea leaves and named it theine. Pure caffeine was first obtained in 1828 (Pelletier and Cavantu). In 1832, its composition was established by Wöhler and Pfaff with Liebig.In 1838, Yobst and G. Ya. Mulder proved the identity of theine and caffeine.

    The structure of caffeine was elucidated by the late 19th century by Hermann Emil Fischer, who was also the first person to synthesize caffeine artificially. He won the 1902 Nobel Prize in Chemistry, which he received in part for this work.

    The discovery of coffee dates back to around 850 AD. e., but its full recognition came many centuries later. It is believed that the Ethiopian ancestors of the Oromo peoples were the first to notice the invigorating effect of coffee.In Europe, coffee appeared in the first half of the 16th century and became no less popular than in Muslim countries. In Europe, the first accurate and complete characterization of the coffee tree was given by Prosper Alpini, an Italian physician from Padua, after Alpini accompanied the Venetian embassy to Egypt in 1591.

    The first cup of coffee was offered to Europeans in Rome in 1626 by the papal diplomatic representative of the Pope della Balle, who became addicted to coffee in Iran. 20 years later, the first coffee shop appeared in Venice, then coffee shops appeared in Marseille and France.It is believed that in this way the growing popularity of coffee in a number of European countries was attested. Nevertheless, the healers of those times rebelled against the use of coffee.

    As al-Jaziri wrote, the first person to taste coffee in 1454 was the Mufti of Aden, Sheikh Jamal al-Din al-Dhabhani. One of the first known mentions of coffee in Russia dates back to 1665. It was in this year that the court physician Samuel Collins prescribed the following recipe to Alexei Mikhailovich, the father of Peter I: “ Boiled coffee, known by the Persians and Turks, and usually after dinner, there is pretty much a cure for arrogance, runny nose and headache “.

    At the beginning of the 18th century, Emperor Peter I made a great contribution to the spread of coffee in Russia. Having become addicted to this drink in Holland, he introduced it into the custom at his assemblies. The story tells how Peter I, while in Holland, often visited and even lived for some time with the burgomaster of Amsterdam Nikolaas Witsen, a well-known businessman and coffee merchant at that time. By order of Peter I, coffee was treated even at the entrance to the cabinet of curiosities.

    Chemical composition and role of caffeine in medicine

    Caffeine – colorless or white bitter crystals.It is a psychostimulant, found in coffee, tea and many soft drinks.

    Chemical formula of caffeine: C8h20N4O2.

    In medicine, caffeine is used as part of remedies for headaches, for migraines, as a stimulant of respiration and cardiac activity in case of colds, to increase mental and physical performance, to eliminate drowsiness.

    The chemical name for caffeine is 1,3,7-trimethyl-xanthine. In an alkaline environment, it turns into caffeidine C7h22N4O.Caffeine has a better effect on the central nervous system.

    Caffeine gives a positive reaction, when heated with Nessler’s reagent, caffeine forms a red-brown precipitate.

    Caffeine overdose

    In case of an overdose, the following symptoms occur: abdominal pain, agitation, anxiety, mental and motor agitation, confusion, dehydration, tachycardia, arrhythmia, hyperthermia, frequent urination, headache, increased tactile or pain sensitivity, tremor or muscle twitching; nausea and vomiting, sometimes with blood; ringing in the ears, epileptic seizures (in acute overdose – tonic-clonic seizures).

    Caffeine in doses of more than 300 mg per day can cause anxiety, headache, tremors, confusion.

    Mental disorders due to the use of caffeine

    It has been suggested that caffeine in large doses or with chronic abuse can induce psychosis in healthy people or exacerbate an existing psychosis in schizophrenic patients

    Caffeine in high doses with chronic use can lead to depletion of the nervous system, which can become the basis for subsequent psychosis.

    In more severe cases, a deeper clouding of consciousness may be present, accompanied by senseless motor excitement. In these cases, the subsequent complete amnesia is frequent and the clinical picture is closer to the twilight clouding of consciousness.

    There is a known case when an elderly woman who had consumed 300 grams of coffee daily for two years experienced psychosis with disorientation in the surrounding space, episodic visual hallucinations, euphoria, which ended in death.

    Daily value of coffee

    An adult is recommended to consume no more than 100-200 mg of caffeine at a time. The optimal amount of coffee for the daily value is no more than 400 mg of caffeine or 3-5 cups of drink per day.

    Caffeine content in various drinks

    Filter coffee (150 ml) – 60-180 mg, on average – 115 mg.

    Black coffee brewed in a coffee machine (240 ml) – 65-120 mg.

    Espresso (30 ml) – 30-60 mg.

    Cappuccino – 70-80 mg.

    Instant coffee (150 ml) – 60-85 mg.

    Energy drinks – not more than 30 mg

    Coffee Experiment

    My mom likes to drink a cup of coffee in the morning every day, my friend drinks energy every day. This will help us in an experiment aimed at finding out whether caffeine affects a person’s blood pressure.

    Description of experiment

    The basis of our experiment will be to measure and record the blood pressure of a person at rest without drinking caffeine and at rest with caffeine.

    Test subject Floor Age Pressure measurements without caffeine in the body Pressure measurements with caffeine in the body Decaffeinated state in the body Condition with caffeine in the body
    Friend Female 19 111/70 119/70 fatigue cheerful
    Mama female 37 115/80 130/80 fatigue cheerful

    Before the first blood pressure measurement, my mother and friend did not use any form of caffeine.Before the second measurement, my mom drank a 300 ml cup of coffee, and my friend drank 500 ml of an energy drink.


    • Caffeine is a psychostimulant. The subjects observed the appearance of appetite, increased activity after taking caffeine.
    • After taking caffeine in various forms, the subjects felt a sense of vigor, their blood pressure increased by 10%
    • With frequent use of caffeine, addiction arises, without caffeine in the body, a person feels terrible.
    • Eliminates lethargy and drowsiness.

    To write this work, the resources of the Internet were used.


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    90,000 Scientists have refuted the opinion about the dangers of coffee with arrhythmias

    Coffee reduces the risk of developing arrhythmias, American scientists have found – each additional cup a day reduces it by 3%. The exact defense mechanism, however, is not yet clear – perhaps it is the antioxidant and anti-inflammatory properties of coffee, or the effect of caffeine on the production of certain substances in the body.

    Doctors often advise drinking less coffee for those who are at increased risk of arrhythmia – it is believed that caffeine can have a bad effect on the heart rate. But this recommendation is based on a small study from the 1980s, the results of which have not received sufficient confirmation afterwards.

    Experts from the University of California at San Francisco decided to test how coffee consumption affects the risk of arrhythmia. To do this, they used data from the UK Biobank repository of medical and genetic information.

    Researchers have collected data on health status, genetics and frequency of coffee consumption of more than 386 thousand people. On average, they drank 1-4 cups of coffee a day. For five years, arrhythmia has developed in almost 17 thousand participants.

    After adjusting for demographics, habits, comorbidities, and other factors, scientists found that coffee love does not contribute to arrhythmias.

    Moreover, each additional cup of coffee a day reduced the risk of arrhythmia by 3%.

    Scientists talked about this in more detail in an article in the journal JAMA Internal Medicine.

    The analysis showed that coffee contributed to a more rare development of atrial fibrillation and supraventricular tachycardia, common heart rhythm disturbances.

    The researchers also drew attention to genetic variants that affect the metabolism of caffeine. However, they also did not affect the risk of developing arrhythmias.

    “Coffee is the primary source of caffeine for most people and has a reputation for causing or aggravating arrhythmias,” the authors write.- The first studies supported this concept, but subsequent results could not be reproduced. However, the prevailing opinion among the general public and medical professionals is that caffeine usually provokes arrhythmias. ”

    The specific mechanisms by which coffee may reduce the likelihood of developing arrhythmias are not yet clear, but the authors of the work offer several possible explanations. First, atrial fibrillation often occurs when the refractory period is shortened – the period of time when the heart muscle does not respond to stimuli.Caffeine lengthens the refractory period, which leads to the normalization of the heart rate.

    In addition, caffeine blocks receptors for adenosine, a substance that plays a role in energy transfer. An excess of adenosine can lead to atrial fibrillation, and this limitation seems to avoid this.

    The antioxidant and anti-inflammatory properties of coffee may also play a role.

    The researchers emphasize that the data on coffee consumption was based on self-reports, which could distort them.Also, they did not have detailed information about what kind of coffee the participants drank and what other caffeinated drinks they drank. However, in general, the results do not contradict the studies of recent decades and, apparently, are accurate enough to be considered significant, scientists say.

    “Widespread bans on caffeine consumption to reduce the risk of arrhythmias are likely unfounded,” they conclude.

    They remind that coffee consumption is associated with a lower risk of cancer, diabetes, Parkinson’s disease and other diseases, as well as with a longer life expectancy.Of course, coffee is not a panacea, but it is a healthy and safe drink that should not be discarded if there are no pronounced contraindications such as exacerbation of gastritis.

    Earlier, a team from the University of Colorado also found out that coffee can protect against heart failure. Using neural networks, scientists analyzed data from participants in several large studies of heart disease that lasted at least 10 years.

    Consuming one or more cups of coffee a day has been found to reduce the risk of heart failure in the long term.

    On average, a cup of coffee a day reduced risks by 5-12%. Those who drank at least two cups of coffee a day had a 30% lower risk of heart failure. Further examination of the data showed that any source of caffeine seemed to improve the outlook.

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    Named a product dangerous to combine with coffee: Society: Russia: Lenta.ru

    Weight loss specialist Pavel Isanbaev spoke about the harmful combination of coffee with sweets. RIA Novosti writes about it.

    According to him, coffee temporarily increases blood glucose levels, and while drinking this drink with dessert, glucose rises excessively, and then drops sharply, which can lead to hypoglycemia. Its main symptoms are weakness, dizziness, cold clammy sweat, and drowsiness.

    In addition, Isanbayev warned, coffee contains antinutrients – substances that prevent the absorption of trace elements and vitamins from food.

    Earlier, nutritionist Nuria Dianova spoke about the unexpected benefits of coffee for weight loss. She pointed out that if people want to burn fat, then a cup of regular coffee, if taken some time before exercise, will increase the heart rate. “The main thing is to control it. Because effective fat burning also occurs in a certain corridor of heart rate, ”said the doctor. She also told how many cups of coffee you can drink per day without harm to health. If you consider the drink as a psycho-stimulating agent, then you should not consume more than two cups a day.Otherwise, addiction can form, which will lead to depletion of the nervous system. Ideally, the second portion of the drink should be consumed no later than afternoon tea, and refuse it six hours before bedtime.

    In February, scientists named coffee consumption as one of the ways to prevent fatty liver disease, which is expressed by excess fat deposition in hepatocytes, as well as other dangerous diseases, including type 2 diabetes and cancer. The researchers analyzed a number of scientific papers that examined the beneficial effects of coffee on the human body.According to one study, the effect of the drink is due to the effect on liver enzymes, which reduces the accumulation of fat, as well as getting rid of toxic substances that can cause the appearance and development of malignant tissues. Coffee also increases the amount of protective antioxidants in the body.

    90,000 Potential benefits with judicious use

    O.V. Shvets

    Tea, coffee and other caffeinated beverages are consumed daily by more than 90% of adults around the world.Caffeine itself (1,3,7-trimethylxanthine) is a naturally occurring plant alkaloid. It is considered the most used pharmacologically active substance on Earth. The most extensive data on the health effects of caffeine come from studies in which large groups of people themselves reported the level of consumption of caffeinated beverages. Further, the relationship of consumption with the frequency of various diseases, positive and negative effects on health was studied. This approach is inevitably associated with the complexity of interpretation, since various physiological processes, in addition to caffeine, can be influenced by many other substances that enter the body with food, drinks, inhaled air, etc.Nevertheless, the information collected in different countries allows us to speak about the influence of the use of caffeine-containing drinks on the neuropsychological sphere of a person, his cardiovascular, endocrine and digestive systems. The peculiarities of their effects can be associated with genetic, age, sex factors, medication intake and environmental exposure.

    Consumption of beverages containing coffee n
    Safe level
    For most adults, drinking 400 mg of caffeine per day has been recognized as safe for the last decades [1].The latest scientific evidence for safe levels of caffeine intake was formulated and published by experts from the European Food Safety Administration (EFSA) in 2015 [2].

    There is strong scientific evidence that a healthy adult can consume 200 mg of caffeine at one time without any negative health effects. At the same time, EFSA recommends that pregnant women limit their caffeine intake to less than 200 mg per day [2].
    To represent these quantities in the form of drinks we are accustomed to, let us say that a cup of natural filtered coffee contains 90 mg of caffeine, half of this amount is in a cup of black tea.A typical energy drink package (250 ml) contains slightly less caffeine (82 mg) than a cup (200 ml) of instant coffee (90 mg). For more information on the caffeine content of various drinks and products, see the table.

    Information on the consumption of caffeine
    Unfortunately, current, objective information on the consumption of these drinks is not available in all countries. However, in the United States, for example, more than 150 million people drink coffee every day, making it an important health factor.The average consumption of coffee in the United States is about two cups (a cup in the United States is considered to be a volume corresponding to 240 ml), which is equivalent to 280 mg of caffeine per day. People who drink four or more cups of coffee per day (> 560 mg of caffeine per day) are classified as high coffee consumption. Men consume more coffee than women. This drink dominates tea in developed countries, especially in Europe (except England and Ireland), Australia and North America. The population of developed countries consumes more than 70% of all coffee [3] drunk in the world (Fig.).

    In developing countries, people prefer tea (over 75% of world consumption), especially in Latin America and Asia. Tea is second only to water in terms of consumption by the world’s population and is 3 times higher than coffee [3].
    Soda containing caffeine is another significant source of caffeine, especially for children, adolescents and young people. There are hundreds of different brands on the market that produce drinks that contain caffeine.For healthy children, drinking small amounts of caffeine is not dangerous [4]. Small amounts, for example, in Canada mean 2.5 mg per kg of body weight of a child [5].

    Active substances and their transformation in the body
    The absorption of caffeine is intense and rapid in the alimentary canal. After that, liver enzymes belonging to the cytochrome P450 1A2 (CYP1A2) system carry out demethylation of caffeine. Defects in the CYP1A2 enzyme lead to lengthening of the half-life of caffeine and prolongation of its effects [6].Genetic polymorphisms affecting metabolic pathways involving CYP1A2 may partly explain the inconsistency of studies on the effects of caffeine on human health.
    Caffeine is an antagonist of adenosine receptors in the central and peripheral nervous system, thus, it stimulates the production of neurotransmitters with pronounced excitatory properties [7].

    In addition to caffeine, coffee and tea contain other components that can affect the physiological mechanisms in the human body.Among the sufficiently studied substances, the following can be distinguished.

    • Chlorogenic acid, found in coffee and black tea, increases the concentration of homocysteine ​​in blood plasma [8]. In addition, coffee polyphenols, such as caffeic and chlorogenic acids, are able to prevent carcinogenesis by affecting the synthesis of proteins that inhibit tumor growth [9].
    • Diterpenoids found in unfiltered coffee have an adverse effect on fat metabolism, increasing plasma levels of atherogenic low-density lipoproteins and reducing beneficial high-density lipoproteins [10].
    • Experimental studies on rat liver cell material have shown that coffee stimulates the production of antitoxic enzymes (eg glutathione S-transferase), protecting tissues from damage [11].
    • Unidentified components of coffee, most likely not caffeine, activate the sympathetic nervous system and can cause high blood pressure [12]. This effect is short-lived and is noted in people who occasionally drink coffee. They may have high blood pressure even when consuming decaffeinated coffee.
    • Some other antioxidants are also present in coffee, cocoa and tea, the specific activity of which varies widely. They can cause a variety of positive effects on the body [13]. Antioxidants mostly pass unchanged through coffee filters.

    The pharmacological effects of medicinal products containing caffeine have been studied in hundreds of serious clinical studies. Considering that its amount in such preparations ranges from 100 to 200 mg, the dose that enters the human body with ordinary foods and drinks is similar.Thus, the results from drug studies can be extrapolated to people who drink significant amounts of caffeinated beverages every day. In addition, studies have been conducted on the impact of the systematic consumption of food and beverages. The results obtained in such observations for various organs and systems of the body are given below in the form of a digest. It should be noted that not all aspects of the effect of caffeine are now finally established, and scientists have a wide field for further research on the properties of this plant alkaloid, which stimulates many physiological functions of the human body.

    Specific physiological effects of caffeine
    Effects on the nervous system and higher nervous activity
    There are some contradictions in the results of studies of caffeine. It notes its proven effect on a person’s ability to assimilate knowledge and improve mood, including short-term and long-term stimulation. However, scientists report that such effects vary greatly in different groups (for example, at different ages or in the presence of concomitant diseases), and also vary significantly depending on the dose and duration of use [14].

    The use of caffeine leads to stimulation of attention, mobilization of mental energy and the ability to concentrate, especially in a state of fatigue and when working at night. Obviously, this is the main reason for the regular consumption of caffeine in humans. Caffeinated beverages and foods can help alleviate the effects of insufficient sleep, including by affecting a range of mental functions. A meta-analysis of 13 randomized trials involving people with sleep disturbances due to long flights or shift work found a positive effect of caffeine consumption on thought formulation, reasoning, memory, orientation, attention, and comprehension compared with placebo [15].It is worth noting that, contrary to the previously prevailing opinion, these effects are in no way associated with withdrawal syndrome, that is, with the refusal of caffeine, the listed parameters do not worsen.

    Caffeine can have exactly the opposite effects on this common problem.
    On the one hand, it has long been known to have an analgesic effect, due to which it is widely used to treat headaches both alone and in combination with other drugs.An analysis of high-quality clinical trials demonstrates a good analgesic effect of combination drugs with caffeine (acetylsalicylic acid, paracetamol and caffeine) for spastic headache and / or migraine compared with the use of paracetamol alone or low doses of ibuprofen [16].

    On the other hand, long-term habitual caffeine consumption may be associated with chronic migraines. Comparison of people who are constantly under the influence of caffeine and those who avoid consumption of the corresponding foods and drinks shows that the former have a relative risk of migraine headaches 2.9 times higher than the latter [17].

    This conflicting information does not allow for an unambiguous conclusion in favor of or against the use of caffeine. In any case, people with headaches need to make an effort to find out the causes and treat their caffeine intake with caution.

    Parkinson’s disease
    The relationship between the risk of Parkinson’s disease and the consumption of tea and coffee has been the subject of several serious studies. The generalized results indicate that the consumption of these drinks leads to a decrease in the likelihood of illness, and this effect is dose-dependent [18].At the same time, specific protective mechanisms remain unclear.

    Such an obvious protective effect is not observed in women taking hormone replacement therapy after the cessation of menstruation. In these women, it appears that caffeine may increase the likelihood of Parkinson’s disease due to interactions with hormonal drugs [19]. In a nursing health study, high coffee consumption (more than six cups a day) was associated with a fourfold increase in the risk of developing this condition in women taking hormones.

    Alzheimer’s disease
    Unfortunately, large-scale studies of the relationship between the consumption of caffeinated foods and beverages and the incidence of Alzheimer’s disease have not yet been carried out. However, several small studies have shown a 30% reduction in the risk of developing this disease in people who regularly drink coffee compared to “coffee abstainers” [20]. In addition, laboratory animals supplemented with caffeine show a lower risk and slow progression of Alzheimer’s disease [21].

    Psychiatric Effects
    The effects of caffeine are associated with a wide range of psychiatric symptoms. At the same time, there is still no strong evidence of a causal relationship. Immediately after ingestion of substantial amounts of caffeine, healthy subjects may experience anxiety, nervousness, insomnia, and irritability. Patients with a history of anxiety are more susceptible to these effects of caffeine [22]. A US study of 3,600 adult twins showed that caffeine intake was associated with an increase in the overall prevalence of anxiety, depression, antisocial behavior and drug addiction, especially in people who regularly drink large amounts of coffee (more than six cups a day) [23].However, after adjusting the results for genetic and environmental factors, the association between mental disorders and caffeine is considered unproven by most experts.

    Interesting results were obtained in a population study that included more than 50 thousand women who did not report cases of depression before the start of the study and were interviewed to establish the frequency of depression after 10 years. It turned out that increasing consumption of caffeinated coffee dose-dependently reduces the likelihood of depression [24].

    Effects on the cardiovascular system
    The relationship of caffeine intake with various parameters of the functions of the heart and blood vessels is the most well studied. This topic deserves a separate publication. Summarizing the most recent highly evidence-based studies, it can be said that traditional opinions about the negative effects of caffeine are not supported.

    For example, low to moderate coffee consumption (up to three cups a day) has been found to protect against myocardial infarction.It has also been demonstrated that subjects who are accustomed to coffee and tea do not run the risk of developing serious diseases of the heart muscle, they do not have a significant increase in blood pressure and heart rate. Only large amounts of caffeine in people who are sensitive to it can lead to adverse effects, including the provocation of disturbances in the heart rhythm and blood circulation in the vessels of the heart.

    Effects on metabolism and the endocrine system
    Taking caffeine is associated with a decrease in the risk of diabetes.Although short-term trials demonstrate the potential for tissue insulin resistance and impairment of glucose tolerance immediately following caffeine intake [25], several large, long-term studies show that tea and coffee consumption is associated with improved insulin sensitivity and better glucose control. in patients with diabetes mellitus [26].

    The reliable mechanisms of such effects are not yet clear. Modern hypotheses are based on the following points:
    • an increase in the consumption of caffeinated coffee leads to an increase in the level of adiponectin, a hormone that reduces tissue resistance to insulin [27];
    • caffeine increases the transport of glucose into muscle tissue [28];
    • in laboratory animals, an increase in the production of insulin and an increase in sensitivity to it have been established against the background of prolonged administration of caffeine [29].

    Diabetes mellitus type 2
    Numerous large-scale studies around the world have shown a reduction in the risk of this extremely common disease with an increase in coffee consumption. A similar beneficial effect has been noted in studies of non-diabetic subjects, including those with impaired glucose tolerance. At the same time, a protective effect of coffee against diabetes has been noted for decaf coffee as well. This suggests a leading role for other coffee components.It should be noted that there was no significant difference in the severity of such a positive effect when consuming different types of coffee (instant, filtered, espresso, etc.) [30].

    Digestive system
    Constipation. Since caffeine is a stimulant of smooth muscle contractions, it is logical to assume that it should influence bowel movement. A study of 1705 women with constipation showed a moderate decrease in the severity of the latter when consuming coffee [31].However, the same study demonstrated an increase in constipation when drinking tea, which seems to be due to the leveling of the effect of caffeine on smooth muscle by other components that are contained in this drink.

    Cirrhosis of the liver. Coffee consumption has been found to be associated with a reduced risk of liver cirrhosis. In a meta-analysis of 16 empirical studies, regular coffee drinkers were 39% less likely to develop this serious illness than coffee abstainers [32].
    Regular coffee consumption is also associated with a decrease in the rate of progression of morphological changes in the liver in chronic viral hepatitis C.

    Malignant neoplasms
    To date, no association has been demonstrated between caffeine consumption and an increased risk of cancer [33].
    It is well known that coffee and tea are high in antioxidants. Taking this fact into account, it would be theoretically logical to assume a decrease in the likelihood of cancer with constant use.Nevertheless, there are difficulties in conducting appropriate studies (first of all, the duration is the main problem, since ten years of observations are required for the corresponding conclusions). A systematic review published this year cites conflicting evidence regarding the association between green tea consumption and cancers of the digestive system, prostate, breast, lung, ovary, and bladder [34].

    Breast cancer. The relationship between caffeine consumption and the risk of this leading form of cancer in women is not well understood.Several studies have shown a reduction in risk with regular coffee consumption, but such findings are not consistent with all observations. In addition, no randomized trials have yet been conducted.
    • In one study of 1690 women with specific mutations associated with breast cancer (BRCA1, BRCA2), coffee consumption was associated with a 69% reduction in tumor risk [36].
    • Another study of 1,932 breast cancer cases and 1,895 control women found a 40% reduction in the likelihood of developing cancer in women who drank caffeinated coffee.No positive or negative effects of consumption of black tea or decaffeinated beverages were noted [37].
    • In a French study examining the effect of dietary supplementation on breast cancer risk in 4,396 healthy women, herbal tea was found to reduce the risk of tumors over a seven-year follow-up. This effect has not been confirmed for coffee and black tea [38].
    • A large population-based study of the health of women in the United States found no association between the occurrence of breast cancer and the consumption of coffee, tea, cola, chocolate or similar decaffeinated foods and beverages [39].

    Lung cancer. Results from meta-analyzes performed suggest that caffeinated coffee may increase the risk of lung cancer [39]. At the same time, drinking decaffeinated coffee [39] and green tea reduces this risk [40]. However, in nonsmokers, the association between coffee consumption and cancer is on the borderline. This means that the association may largely be due to the complex effects of tobacco smoke and caffeine.

    Cancer of the digestive system. Empirical studies suggest that coffee consumption may be associated with a reduced risk of digestive cancers such as pharyngeal and laryngeal cancers and liver cancer. The influence of other factors remains quite highly probable.

    Cancer of the pharynx and larynx. A meta-analysis of one population study and six case-control studies found that regular coffee consumption reduced the risk of malignant lesions of the mouth, pharynx and larynx by 36% [41].

    Liver cancer. Several empirical studies have suggested that coffee is a protective factor against liver cancer, including hepatocellular carcinoma. A meta-analysis found a 43% reduction in the risk of liver malignancy when drinking two or more cups of coffee a day [42].

    Prostate cancer. Regular consumption of both coffee and green tea leads to a dose-dependent reduction in the risk of developing prostate cancer [43].
    In a prospective study of 5035 men over 20 years, 642 deaths of prostate cancer were identified. High coffee consumption has been associated with an 18% reduction in cancer risk [44].

    In a Japanese study involving about 50,000 men, it was demonstrated that drinking five or more cups of green tea a day leads to a 48% reduction in the risk of prostate cancer compared with men who drink less than one cup of green tea daily [45] …

    Musculoskeletal system
    Osteoporosis. The conventional wisdom is supported by the results of clinical studies, especially in women with low calcium intake. In these women, the abuse of caffeine-containing drinks is fraught with a decrease in bone density and an increase in the likelihood of fractures.
    Experts emphasize that the risk is clearly increasing for older women, thin, with a calcium intake of less than 800 mg / day, who constantly consume significant amounts of coffee (more than five cups a day) [46].

    At the same time, in women who prefer tea, in several studies, an increase in bone mineral density was determined, although such changes did not lead to a decrease in the risk of fractures. It is believed that the higher bioflavonoid content in tea compared to coffee causes a greater accumulation of minerals in the bone tissue [47].

    Arthritis. Although one study showed an increased risk of rheumatoid arthritis in people who consumed four cups of decaffeinated coffee a day [48], several large studies found no association between caffeinated coffee consumption and rheumatoid arthritis [49. 50].

    A clear inverse relationship has also been found between coffee consumption and blood uric acid [51]. Thus, in a 12-year study involving 45,869 men without a history of gout, the incidence of this common joint ailment decreased in the coffee-addicted group [53]. And here there was a dose-dependent effect. Similar effects were noted for decaffeinated coffee, but not for tea.

    Urination. Caffeine intake is associated with an increase in urinary frequency and urine volume, while caffeine restriction has the opposite effect [53, 54].
    Improving athletic performance. The increase in physical performance under the influence of caffeine is well known and extends to various types of physical activity, including endurance competitions, team sports, high-intensity, short-term competitions, for example, in swimming disciplines [55].

    The maximum effect is achieved with the use of small and medium doses of caffeine (2-3 mg / kg), when there are a minimum of side effects. The International Olympic Committee will disqualify athletes with urine caffeine levels greater than 12 μg / ml [56].Taking into account the individual characteristics, this level of excretion can be achieved with the consumption of three to six cups of coffee a day [57]. Therefore, athletes should be warned not to exceed the limit of 2-3 cups of coffee per day or an equivalent amount of caffeinated foods and beverages.

    Most, but not all, studies show an inverse relationship between coffee consumption and all-cause mortality [58-60].One possible explanation for this phenomenon is that healthy people are more likely to choose and consume caffeinated beverages than sick people.

    A meta-analysis (2014) of 18 prospective studies evaluated the association between coffee consumption and mortality. The findings indicated that drinking four cups of coffee a day resulted in a 16% reduction in all-cause mortality [61].

    The largest studies in the history of medical science – the study of the health of health workers (n = 41 736) and the study of the health of nurses (n = 86 214) with patient follow-up for 18 and 24 years, respectively – studied including and this aspect.The relative risk of death from all causes compared between groups drinking less than one cup of coffee a day and drinking more than six cups was 0.8 for men and 0.83 for women. This means that drinking even very large amounts of coffee is associated with a 17–20% reduction in mortality [62, 63].

    It should be emphasized that the decrease in the likelihood of premature death occurs primarily due to the factor of cardiovascular diseases. Thus, the traditional opinion about the negative effect of caffeine on cardiovascular morbidity and mortality can be considered without reliable evidence.

    Caffeine dependence, abuse and withdrawal
    As discussed above, up to 90% of adults in some countries consume caffeinated beverages daily to maintain an active lifestyle, taking into account the potential of caffeine to improve mental performance [64].

    Although the terms “caffeine dependence” and “caffeine abuse” are common in the literature, the clinical manifestations of these conditions have not yet been clearly defined [65].At the same time, the withdrawal syndrome has fairly clear criteria and, in severe cases, may require appropriate medical intervention.

    One can speak of caffeine dependence if a person has one of the following three signs:
    • addiction;
    • withdrawal syndrome;
    • use in larger quantities than necessary;
    • a constant desire to control and reduce the amount of caffeine consumed;
    • a large amount of time spent obtaining, using or recovering from caffeine intake;
    • deterioration in the performance of professional, social and other tasks;
    • use continues despite physical or psychological problems.

    Caffeine abuse can be talked about in cases where its consumption affects a person’s usual lifestyle.
    The above signs of dependence and abuse are universal for many psychoactive substances [66]. Not all experts share the spread of these traits to caffeine. First of all, this is due to the fact that the difficulties of quitting the use of caffeine and continuing to consume it, despite the harm to human health, are not a systematic phenomenon.In addition, there is no strong evidence for caffeine addiction. Therefore, the terms “caffeine addiction” and “caffeine abuse” are not included in the classifiers of psychiatric disorders where drug and alcohol addiction is present.

    Withdrawal syndrome. The presence of adverse symptoms after refusal to consume caffeinated beverages by people who regularly drank such beverages has been reliably confirmed by the results of serious studies [67], including in studies conducted in twins, the genetic background of this phenomenon was revealed [68].

    Most scientists classify specific symptoms as [67]:
    • headache;
    • fatigue / fatigue;
    • decreased energy / activity;
    • decreased alertness / attention;
    • lethargy / drowsiness;
    • deterioration of health;
    • depressed mood;
    • difficulty concentrating;
    • irritability.

    The listed symptoms can occur with the refusal of the constant use of even small doses of caffeine (100 mg / day), but their severity increases with an increase in the dose of excluded caffeine [67].Withdrawal syndrome is more likely to occur 12-24 hours after stopping caffeine use and can last up to 9-10 days. The symptoms disappear within 30-60 minutes after the return to the consumption of caffeinated foods or drinks. If there is an objective need to abandon the discussed plant alkaloid, a gradual (within a week) reduction in its dose is recommended. It should be noted that only half of people who suddenly stop taking caffeine experience the symptoms described [67].

    Currently, an active study of the physiological effects of caffeine consumption continues, and all the “i” s have not yet been dotted. Overall, nutritional science is among the fastest growing medical disciplines. Thanks to this, there is a constant accumulation of evidence necessary to formulate practical recommendations for our patients and healthy people. If modern data are not enough to provide informed recommendations, we try to provide the fullest possible objective information based on the results of serious research.Having studied such data, our reader will be able to make his own informed choice and even give advice to his loved ones.

    Summarizing a review of relevant information on the benefits and risks of caffeine consumption, as well as drinks and foods that contain it, we can say that many, if not most of the traditional hypotheses about the dangers of caffeine have been refuted by evidence-based studies. Does this mean that caffeine from various sources should be recommended for all people to prevent specific diseases? It’s probably too early to talk about it.There is a need for more long-term studies of all aspects of the effects of caffeine on the human body. However, we can already state the fact that moderate consumption of drinks and products containing caffeine is not only safe, but can also bring proven benefits.

    References are being revised.

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    Self-help rehabilitation of COVID-19: recommendations for patients

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    that is due to mechanical ventilation of the legends), but it is also often spared in children due to a light coronavirus infection. Patients with chronic inheritance of COVID-19 (the so-called postkovidny syndrome) require all-in-one multidisciplinary rehabilitation from students of medical specialists (physiotherapists, neurologists, neurologists)). In a wide range of materials, recommendations have been made for the rehabilitation of the COVID-19 issue, for the destruction of the All-Russian Organization
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    90,000 Benefit or harm? 5 tips on how to drink coffee without damaging your teeth

    YEREVAN, August 14.News-Armenia . A good half of the world’s population does not start the morning without a cup of aromatic coffee. Such popularity of the drink is explained by its outstanding tonic properties and excellent taste. But is it as useful as connoisseurs assure? And most importantly, how does coffee affect the condition of your teeth? The question was dealt with by kiz.ru.

    Chemical composition

    In simple terms, coffee beans are 50% carbohydrates (naturally occurring sugars and fiber), oils and water.In the process of roasting, the grain loses almost a fifth (up to 18-19%) of moisture, while increasing in size by about 1.5 times. The dark color of the beans is due to the caramelization of the sugars. Fats break down into acids, and fiber breaks down into acids and alcohols.

    Mechanism of action

    The main component of the drink for which it is so appreciated is caffeine. This substance belongs to the group of alkaloids, has a bitter taste and the ability to inhibit the receptors that produce adenosine (sleep hormone).

    Caffeine stimulates the central nervous system, increases heart rate, increases blood pressure, has a diuretic effect, and reduces platelet aggregation (adhesion). As a result, the drink invigorates, activates thought processes and increases efficiency.

    How coffee affects enamel

    Any coffee lover knows that regular consumption of your favorite drink does not leave a trace on your teeth. But the effect of coffee on enamel is not as straightforward as it is usually portrayed.This coin also has two sides.

    Positive side

    Scientists have proven that coffee has bactericidal properties, therefore, in theory, the drink should inhibit the pathogenic microflora in the mouth. And she, along with poor hygiene, is the main culprit in the appearance of tooth decay.

    It hardly makes sense to drink coffee in order to prevent caries (it is better to use special rinses), but you can be sure at least that the drink does not contribute to its appearance (provided that it is consumed without sugar, caramel, chocolate and other sweet additives).

    In addition, regular (but moderate!) Consumption of high-quality brewed coffee is the prevention of cancer, in particular throat cancer. Perhaps this is the whole benefit for the oral cavity.

    A spoonful of coffee tar

    The main claim of dentists to coffee is its negative effect on the color of the enamel. It’s no secret that coffee lovers often have yellow or light brown teeth. The drink has pronounced coloring properties, moreover, it is usually consumed hot.Against this background, the teeth receive a double blow – chemical and thermal, which, in the presence of microcracks in the enamel, leads to a slow destruction of the protective shell.

    Another disadvantage – coffee provokes the formation of dental plaque, especially if the drink contains sugar, caramel, chocolate, syrups and other sweet additives. But even without them, it contains a large amount of heavy carbohydrates, naturally occurring sugars and cocoa butter. These substances leave sediment on the teeth and mucous membranes in the mouth, and this is an ideal environment for the reproduction of pathogenic microflora.

    How to drink coffee without harm to enamel

    If you want to have white teeth, but are not ready to give up coffee, you need to adhere to the following recommendations:

    • Minimize the number of cups you drink. This will have a beneficial effect on the health of not only teeth, but also the whole body.
    • Prefer cappuccino and latte. These drinks are less strong than espresso and milk reduces the coloring properties of the coffee.
    • Minimize or eliminate sugar altogether.This also applies to sugar-containing additives – chocolate, caramel, syrups, and others.
    • Watch your temperature. It is ideal for the teeth that it is roomy. If this drink is not enjoyable, just drink it as little hot as possible.
    • Rinse your mouth after drinking coffee. It is better to use rinse aids, but if they are not on hand, clean water at room temperature will do.

    Following these guidelines will reduce the negative effects of coffee on your teeth, but will not make them whiter.Home hygiene of a coffee lover should be more thorough than that of people who do not consume this drink and do not smoke, and professional hygiene should be more frequent. -0- 90,000 Nine months in safety mode

    Constant stress means sudden changes in hormone levels and an increase in the risk of developing inflammatory reactions. Stress hormones, such as cortisol, can influence the development of stress reactions in the baby too – they will subsequently affect both behavior and physiology 7 .Chronic stress can negatively affect a child’s health even after birth 8 .

    What to do? Learn to relax using relaxation techniques, meditation, psychological techniques, and even moderate physical activity, such as yoga for pregnant women, if your doctor permits it. If the work is accompanied by nervous shocks and brings few positive emotions, it is worth agreeing to change the schedule or responsibilities. Stress can be caused not only by work situations and life circumstances, but also by negative-minded people, so it is worth considering changing your environment.

    To support the nervous system during stress, you can use vitamins of group B, vitamin C, as well as zinc and magnesium. They have a beneficial effect on the functions of the nervous system 9 . No matter how the situation develops, remember that the baby most of all needs a happy and calm mother.

    Bath or shower

    A warm bath is a great way to relax, soak up, put all thoughts out of your head and relieve stress. It is not necessary to give up this pleasure during pregnancy, however, immersion in hot water and prolonged increases in body temperature are best avoided in order to avoid unnecessary exposure to the baby 10, 11 .The best solution would be a shower or a 10-15 minute warm bath with short immersions in water. The water temperature should not exceed 38 degrees.


    There is no need to worry about pets if they are all kept clean, healthy, free from parasites, vaccinated against infections, in particular rabies. Moreover, walking a dog in the park can be not only fun, but also useful: you and your baby need fresh air, as well as positive emotions from your beloved dog.Just try to exclude contact with stray animals in order to avoid infection with echinococcosis and toxoplasmosis 12, 13 . You can get tested for toxoplasmosis by passing a blood test for antibodies to the parasite. However, people usually become infected with this disease when they taste raw minced meat, eat insufficiently cooked meat or poorly washed greens. So just keep your food hygienic and remember to wash your hands before eating. This is useful even for those who do not pet cats.If you have a cat, ask loved ones to clean the litter box, or be sure to wear gloves when changing litter. Plus, to reduce the risk of contracting an animal with rabies, limit it to free walks.

    Working conditions

    By law, you have the right to a safe work environment. If your work involves the use of lead, solvents, paints, formaldehyde, and harsh industrial chemicals, consider changing your occupation, as even harmless jobs such as a printing house or photo studio can be potentially hazardous during pregnancy.