How does methionine impact metabolism. What is the relationship between methionine and oxidative stress. Why is methionine important for disease prevention. What are the key functions of methionine in the body. How does methionine deficiency affect health. What are the optimal dietary sources of methionine. When might methionine supplementation be necessary.

The Biochemical Significance of Methionine

Methionine is an essential amino acid that plays a critical role in numerous biochemical processes within the body. As a sulfur-containing amino acid, it serves as a precursor for other important molecules and participates in key metabolic pathways. Understanding the function of methionine is crucial for appreciating its impact on overall health and disease prevention.

What are the primary biochemical functions of methionine? Methionine acts as:

• A building block for protein synthesis
• A methyl group donor in various biochemical reactions
• A precursor for cysteine and taurine
• An initiator of mRNA translation
• A key component in the synthesis of S-adenosylmethionine (SAM)

These diverse functions highlight methionine’s importance in maintaining proper cellular function and overall metabolic health.

Methionine’s Role in Metabolism Regulation

Methionine exerts a significant influence on various metabolic processes throughout the body. Its involvement in one-carbon metabolism and as a precursor for important molecules like SAM makes it a key player in regulating overall metabolic function.

How does methionine impact energy metabolism? Methionine contributes to energy metabolism by:

1. Facilitating the synthesis of creatine, an important energy source for muscle tissue
2. Supporting the production of carnitine, which is essential for fatty acid oxidation
3. Influencing insulin sensitivity and glucose metabolism
4. Participating in the regulation of mitochondrial function

These metabolic effects underscore the importance of maintaining adequate methionine levels for optimal energy production and utilization within the body.

Methionine and Protein Metabolism

As an essential amino acid, methionine plays a crucial role in protein metabolism. It serves as a building block for protein synthesis and is particularly important as the initiator amino acid in the translation of mRNA into proteins.

How does methionine influence protein synthesis? Methionine affects protein synthesis by:

• Initiating the process of protein translation
• Contributing to the structure and function of various proteins
• Regulating the expression of genes involved in protein synthesis
• Influencing the rate of protein turnover in tissues

These functions highlight the essential nature of methionine in maintaining proper protein metabolism and cellular function.

Methionine and Oxidative Stress: A Delicate Balance

The relationship between methionine and oxidative stress is complex and multifaceted. While methionine itself can be susceptible to oxidation, it also plays a role in the body’s antioxidant defense systems through its involvement in the synthesis of glutathione and other sulfur-containing compounds.

How does methionine contribute to antioxidant defenses? Methionine supports antioxidant function by:

• Serving as a precursor for glutathione, a potent intracellular antioxidant
• Contributing to the synthesis of taurine, which has antioxidant properties
• Participating in the regulation of cellular redox status
• Influencing the expression of antioxidant enzymes

However, it’s important to note that excessive methionine intake can potentially lead to increased oxidative stress, highlighting the need for balanced consumption.

Methionine Sulfoxide and Oxidative Damage

When exposed to reactive oxygen species, methionine can be oxidized to form methionine sulfoxide. This oxidation can affect protein structure and function, potentially leading to cellular damage if not properly managed.

How does the body handle methionine oxidation? The management of methionine oxidation involves:

1. The action of methionine sulfoxide reductases to reverse oxidation
2. Cellular mechanisms to degrade or repair oxidized proteins
3. Regulation of methionine metabolism to maintain redox balance
4. Adaptive responses to oxidative stress that involve methionine-related pathways

Understanding these processes is crucial for appreciating the intricate relationship between methionine and oxidative stress in biological systems.

Methionine’s Impact on Cardiovascular Health

The role of methionine in cardiovascular health is an area of active research and ongoing debate. While methionine is essential for various physiological processes, its metabolism can also produce homocysteine, a compound associated with increased cardiovascular risk when present at elevated levels.

How does methionine influence heart health? Methionine affects cardiovascular function through:

• Its role in homocysteine metabolism and regulation
• Involvement in the synthesis of creatine for cardiac energy metabolism
• Contribution to the production of nitric oxide, a vasodilator
• Influence on lipid metabolism and atherosclerosis development

Balancing methionine intake and metabolism is crucial for maintaining optimal cardiovascular health and preventing related diseases.

Homocysteine: The Double-Edged Sword

Homocysteine, a metabolite of methionine, has been the subject of extensive research due to its potential role in cardiovascular disease. While it is a normal product of methionine metabolism, elevated levels of homocysteine have been associated with increased risk of atherosclerosis and thrombosis.

How can the body regulate homocysteine levels? Homocysteine regulation involves:

1. Adequate intake of B vitamins (B6, B12, and folate) to support its metabolism
2. Proper function of enzymes involved in the methionine cycle
3. Balanced methionine intake to avoid excessive homocysteine production
4. Lifestyle factors that influence methionine and homocysteine metabolism

Understanding and managing these factors is essential for maintaining healthy homocysteine levels and reducing cardiovascular risk.

Methionine in Liver Function and Detoxification

The liver plays a central role in methionine metabolism and utilizes this amino acid in various detoxification processes. Methionine is crucial for the synthesis of S-adenosylmethionine (SAM), a key molecule in liver function and overall health.

Why is methionine important for liver health? Methionine supports liver function by:

• Providing the substrate for SAM synthesis, which is involved in numerous methylation reactions
• Contributing to the production of glutathione, a major hepatic antioxidant
• Supporting phase II detoxification processes in the liver
• Influencing lipid metabolism and preventing fatty liver disease

These functions underscore the importance of maintaining adequate methionine levels for optimal liver health and detoxification capacity.

Methionine and Alcohol-Related Liver Damage

The relationship between methionine metabolism and alcohol-induced liver injury has been a subject of significant research. Chronic alcohol consumption can disrupt methionine metabolism, leading to various hepatic problems.

How does alcohol affect methionine metabolism in the liver? Alcohol impacts methionine-related processes by:

1. Interfering with methionine synthase activity, disrupting the methionine cycle
2. Depleting hepatic SAM levels, affecting methylation reactions
3. Increasing oxidative stress, which can further impair methionine metabolism
4. Altering the expression of genes involved in methionine and homocysteine metabolism

Understanding these interactions is crucial for developing strategies to prevent and treat alcohol-related liver diseases.

Methionine’s Role in Neurodegenerative Disorders

The impact of methionine on brain health and neurodegenerative disorders has gained increasing attention in recent years. Methionine metabolism plays a crucial role in maintaining neuronal function and may influence the development and progression of various neurological conditions.

How does methionine affect brain health? Methionine influences neurological function through:

• Its role in the synthesis of neurotransmitters and their precursors
• Involvement in methylation reactions that affect gene expression in the brain
• Contribution to the maintenance of neuronal membranes
• Influence on oxidative stress and inflammation in neural tissues

These diverse effects highlight the potential importance of methionine in preventing and managing neurodegenerative disorders.

Methionine and Alzheimer’s Disease

The relationship between methionine metabolism and Alzheimer’s disease has been the subject of extensive research. Alterations in methionine-related pathways may contribute to the development and progression of this neurodegenerative condition.

How might methionine metabolism influence Alzheimer’s disease? Potential mechanisms include:

1. Effects on amyloid-beta production and clearance
2. Influence on tau protein phosphorylation and aggregation
3. Modulation of oxidative stress and neuroinflammation
4. Impact on DNA methylation patterns in neurons

Understanding these connections may lead to new strategies for preventing or treating Alzheimer’s disease through targeted interventions in methionine metabolism.

Methionine in Cancer Biology and Treatment

The role of methionine in cancer biology is complex and multifaceted. While methionine is essential for normal cellular function, cancer cells often exhibit altered methionine metabolism, which may contribute to their growth and survival.

How does methionine metabolism differ in cancer cells? Cancer-related alterations in methionine pathways include:

• Increased demand for methionine to support rapid proliferation
• Changes in one-carbon metabolism and DNA methylation patterns
• Altered regulation of methionine cycle enzymes
• Differences in methionine-dependent redox balance

These unique features of cancer cell metabolism have led to interest in targeting methionine pathways for cancer treatment and prevention.

Methionine Restriction as a Potential Cancer Therapy

The concept of methionine restriction as a therapeutic approach for cancer has gained attention in recent years. Some cancer cells exhibit methionine dependence, making them potentially vulnerable to strategies that limit methionine availability.

How might methionine restriction impact cancer treatment? Potential benefits include:

1. Slowing cancer cell growth and proliferation
2. Enhancing the effectiveness of certain chemotherapy drugs
3. Modulating the tumor microenvironment
4. Influencing cancer cell metabolism and energy production

While promising, the application of methionine restriction in cancer therapy requires careful consideration of potential side effects and the need for personalized approaches.

The role of methionine on metabolism, oxidative stress, and diseases

Review

. 2017 Dec;49(12):2091-2098.

doi: 10.1007/s00726-017-2494-2.

Epub 2017 Sep 19.

Yordan Martínez 
^1
 
2
 
3
, Xue Li 
^1
 
2
, Gang Liu 
^4
 
5
, Peng Bin 
^1
 
2
, Wenxin Yan 
^1
 
2
, Dairon Más 
⁶
, Manuel Valdivié 
⁷
, Chien-An Andy Hu 
^{1
 
2
 
8
 
9}
, Wenkai Ren 
^1
 
2
, Yulong Yin 
^1
 
2
 
9

Affiliations

Affiliations

• ¹ Key Laboratory of Agro-Ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha, 410125, Hunan, China.
• ² National Engineering Laboratory for Pollution Control and Waste Utilization in Livestock and Poultry Production, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha, 410125, Hunan, China.
• ³ Department of Animal Production, Faculty of Veterinary Medicine, Agricultural University of Havana, 32700, San José de Las Lajas, Mayabeque, Cuba.
• ⁴ Key Laboratory of Agro-Ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha, 410125, Hunan, China. [email protected].
• ⁵ National Engineering Laboratory for Pollution Control and Waste Utilization in Livestock and Poultry Production, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha, 410125, Hunan, China. [email protected].
• ⁶ Faculty of Natural Sciences, University of Queretaro, Querétaro, Mexico.
• ⁷ Department of Management and Feeding of Monogastric Animals, Institute of Animal Science, 32700, San José de Las Lajas, Mayabeque, Cuba.
• ⁸ Department of Biochemistry and Molecular Biology, University of New Mexico School of Medicine, MSC08 4670, Fitz 258, Albuquerque, NM, 87131, USA.
• ⁹ Animal Nutrition and Human Health Laboratory, School of Life Sciences, Hunan Normal University, Changsha, 410081, Hunan, China.

• PMID:

  28929442

• DOI:

  10. 1007/s00726-017-2494-2

Review

Yordan Martínez et al.

Amino Acids.

2017 Dec.

. 2017 Dec;49(12):2091-2098.

doi: 10.1007/s00726-017-2494-2.

Epub 2017 Sep 19.

Authors

Yordan Martínez 
^1
 
2
 
3
, Xue Li 
^1
 
2
, Gang Liu 
^4
 
5
, Peng Bin 
^1
 
2
, Wenxin Yan 
^1
 
2
, Dairon Más 
⁶
, Manuel Valdivié 
⁷
, Chien-An Andy Hu 
^{1
 
2
 
8
 
9}
, Wenkai Ren 
^1
 
2
, Yulong Yin 
^1
 
2
 
9

Affiliations

• ¹ Key Laboratory of Agro-Ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha, 410125, Hunan, China.
• ² National Engineering Laboratory for Pollution Control and Waste Utilization in Livestock and Poultry Production, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha, 410125, Hunan, China.
• ³ Department of Animal Production, Faculty of Veterinary Medicine, Agricultural University of Havana, 32700, San José de Las Lajas, Mayabeque, Cuba.
• ⁴ Key Laboratory of Agro-Ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha, 410125, Hunan, China. [email protected].
• ⁵ National Engineering Laboratory for Pollution Control and Waste Utilization in Livestock and Poultry Production, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha, 410125, Hunan, China. [email protected].
• ⁶ Faculty of Natural Sciences, University of Queretaro, Querétaro, Mexico.
• ⁷ Department of Management and Feeding of Monogastric Animals, Institute of Animal Science, 32700, San José de Las Lajas, Mayabeque, Cuba.
• ⁸ Department of Biochemistry and Molecular Biology, University of New Mexico School of Medicine, MSC08 4670, Fitz 258, Albuquerque, NM, 87131, USA.
• ⁹ Animal Nutrition and Human Health Laboratory, School of Life Sciences, Hunan Normal University, Changsha, 410081, Hunan, China.

• PMID:

  28929442

• DOI:

  10. 1007/s00726-017-2494-2

Abstract

Methionine is an aliphatic, sulfur-containing, essential amino acid, and a precursor of succinyl-CoA, homocysteine, cysteine, creatine, and carnitine. Recent research has demonstrated that methionine can regulate metabolic processes, the innate immune system, and digestive functioning in mammals. It also intervenes in lipid metabolism, activation of endogenous antioxidant enzymes such as methionine sulfoxide reductase A, and the biosynthesis of glutathione to counteract oxidative stress. In addition, methionine restriction prevents altered methionine/transmethylation metabolism, thereby decreasing DNA damage and carcinogenic processes and possibly preventing arterial, neuropsychiatric, and neurodegenerative diseases. This review focuses on the role of methionine in metabolism, oxidative stress, and related diseases.

Keywords:

Cancer; Disease; Endogenous antioxidant enzyme; Mammalian; Methionine; ROS.

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Grant support

• 161343KYSB20160008/International Partnership Program of Chinese Academy of Sciences
• 2016YFD0500504/National Key Research and Development Program of China
• 31570114/National Natural Science Foundation of China
• 31330075/National Natural Science Foundation of China
• 31110103909/National Natural Science Foundation of China

• 2016VBB007/Chinese Academy of Sciences visiting professorship for senior international scientists

Functions, Food Sources and Side Effects

Amino acids help build the proteins that make up the tissues and organs of your body.

In addition to this critical function, some amino acids have other special roles.

Methionine is an amino acid that produces several important molecules in your body. These molecules are essential for the proper functioning of your cells.

Because of the important molecules it produces, some recommend increasing methionine intake. However, others recommend limiting it due to possible negative side effects.

This article will discuss the importance of methionine and whether you need to worry about the amount of it in your diet. Sources and potential side effects are also discussed.

Methionine is an amino acid found in many proteins, including the proteins in foods and those found in the tissues and organs of your body.

In addition to being a building block for proteins, it has several other unique features.

One of these is its ability to be converted into important sulfur-containing molecules (1).

Sulfur-containing molecules have a variety of functions, including the protection of your tissues, modifying your DNA and maintaining proper functioning of your cells (2, 3).

These important molecules must be made from amino acids that contain sulfur. Of the amino acids used to make proteins in the body, only methionine and cysteine contain sulfur.

Although your body can produce the amino acid cysteine on its own, methionine must come from your diet (4).

Additionally, methionine plays a critical role in starting the process of making new proteins inside your cells, something that is continuously occurring as older proteins break down (1).

For example, this amino acid starts the process of producing new proteins in your muscles after an exercise session that damages them (1, 5).

Summary

Methionine is a unique amino acid. It contains sulfur and can produce other sulfur-containing molecules in the body. It is also involved in starting protein production in your cells.

One of the major roles of methionine in the body is that it can be used to produce other important molecules.

It is involved in the production of cysteine, the other sulfur-containing amino acid used to build proteins in the body (1, 6).

Cysteine can, in turn, create a variety of molecules, including proteins, glutathione and taurine (1).

Glutathione is sometimes called the “master antioxidant” due to its critical role in the defenses of your body (2, 7).

It also plays a role in the metabolism of nutrients in the body and the production of DNA and proteins (2).

Taurine has many functions that help maintain the health and proper functioning of your cells (8).

One of the most important molecules methionine can be converted into is S-adenosylmethionine, or “SAM” (1).

SAM participates in many different chemical reactions by transferring part of itself to other molecules, including DNA and proteins (3, 9).

SAM is also used in the production of creatine, an important molecule for cellular energy (10, 11).

Overall, methionine is directly or indirectly involved in many important processes in the body because of the molecules it can become.

Summary

Methionine can convert into several sulfur-containing molecules with important functions, such as glutathione, taurine, SAM and creatine. These molecules are critical for the normal functions of the cells in your body.

Your DNA contains the information that makes you who you are.

While much of this information may stay the same for your whole life, environmental factors can actually change some aspects of your DNA.

This is one of the most interesting roles of methionine — that it can convert into a molecule called SAM. SAM can change your DNA by adding a methyl group (a carbon atom and its attached hydrogen atoms) to it (3, 9).

The amount of methionine in your diet may affect how much of this process occurs, but there are many unanswered questions about this.

It is possible that increasing methionine in the diet could either increase or decrease how much your DNA changes as a result of SAM (12).

Additionally, if these changes occur, they could be beneficial in some cases but detrimental in others (12).

For example, some research has shown that diets higher in nutrients that add methyl groups to your DNA may lower risk of colorectal cancer (13).

However, other research has shown that higher methionine intake could worsen conditions like schizophrenia, perhaps due to adding more methyl groups to DNA (12, 14).

Summary

One of the molecules produced by methionine, SAM, can alter your DNA. It isn’t fully clear how the methionine content of your diet affects this process, and it is possible that this process is beneficial in some cases and detrimental in others.

Although methionine has important roles in the body, some research shows benefits of diets that are low in this amino acid.

Some cancer cells are dependent on dietary methionine to grow. In these cases, limiting your dietary intake could be beneficial to help starve cancer cells (15).

Since proteins from plants are often lower in methionine than animal proteins, some researchers believe that plant-based diets could be a tool to fight some cancers (15, 16).

Additionally, several studies in animals show that reducing methionine can increase lifespan and improve health (17, 18, 19).

One study found that lifespan was over 40% longer in mice fed a low-methionine diet (17).

This longevity may be due to improved stress resistance and metabolism as well as maintaining the ability for cells of the body to reproduce (20, 21).

Some researchers concluded that the low methionine content acts to actually slow the rate of aging in mice (19).

Whether or not these benefits extend to humans isn’t clear yet, but some test-tube studies have shown benefits of low methionine content in human cells (20, 22).

However, human research is needed before any conclusions can be made.

Summary

In animals, lowering the methionine content of the diet may slow the rate of aging and increase lifespan. Some studies have shown benefits of lowering methionine in human cells, but research is needed in living humans.

While virtually all protein-containing foods have some methionine, the amount varies widely. Eggs, fish and some meats contain high amounts of this amino acid (23).

It is estimated that around 8% of the amino acids in egg whites are sulfur-containing amino acids (methionine and cysteine) (24).

This value is about 5% in chicken and beef and 4% in dairy products. Plant proteins usually have even lower quantities of these amino acids.

Some research has also examined the overall amount of the sulfur-containing amino acids (methionine and cysteine) in different types of diets (24).

The highest content (6.8 grams per day) was reported in high-protein diets, while lower intakes were present for vegetarians (3.0 grams per day) and vegans (2.3 grams per day).

Despite the low intake among vegetarians, other research has shown that they actually have higher blood concentrations of methionine than those who eat meat and fish (25).

This finding led the researchers to conclude that dietary content and blood concentrations of methionine are not always directly related.

However, these studies did find that vegans have both low dietary intake and low blood concentrations of methionine (24, 25).

Summary

Animal proteins often have greater methionine content than plant proteins. Those following a plant-based diet have a lower dietary intake of sulfur-containing amino acids, although they can have either higher or lower levels of methionine in the blood.

Researchers have set a recommended daily intake of the sulfur-containing amino acids (methionine and cysteine), but studies have also examined side effects of higher doses.

Recommended Intake

The daily recommended intake of methionine plus cysteine is 8.6 mg/lb (19 mg/kg) per day for adults, which is around 1.3 grams for someone weighing 150 pounds (68 kilograms) (4).

However, some researchers have recommended consuming double this amount based on the limitations of the studies used to set the recommended intake (24).

The elderly often have low methionine intake, and studies have shown that they may need higher intakes of 2 to 3 grams per day (24, 26).

Despite the fact that certain groups may benefit from increasing their methionine intake, many diets exceed 2 grams per day of methionine plus cysteine.

A variety of diets, including vegan, vegetarian, traditional and high-protein diets are estimated to contain between 2.3 and 6.8 grams per day of these amino acids (24).

Effects on Homocysteine

Perhaps the largest concern associated with high methionine intake is due to one of the molecules this amino acid can produce.

Methionine can be converted into homocysteine, an amino acid associated with several aspects of heart disease (27, 28).

High intakes of methionine may lead to an increase in homocysteine, although some individuals are more susceptible to this process than others (29).

Interestingly, research indicates that potential dangers of high methionine intake may be due to homocysteine rather than methionine itself (30).

However, there are other factors that can alter homocysteine levels.

For example, even though they have a lower dietary intake of methionine, vegans and vegetarians may have higher homocysteine than omnivores due to low vitamin B12 intake (31).

Other research has shown a high-protein, high-methionine diet didn’t increase homocysteine after six months, compared to a low-protein, low-methionine diet (32).

Additionally, altering intake by up to 100% does not appear to affect homocysteine in healthy adults without vitamin deficiencies (33).

Side Effects

To evaluate the body’s responses to methionine, researchers will give a single large dose of this amino acid and observe the effects.

This dose is far larger than the recommended intake, often around 45 mg/lb (100 mg/kg), or 6.8 grams for someone who weighs 150 pounds (68 kilograms) (29).

This type of test has been performed over 6,000 times, with primarily minor side effects. These minor side effects include dizziness, sleepiness and changes in blood pressure (29).

One major adverse event occurred during one of these tests, which resulted in the death of an individual with high blood pressure but good health otherwise (34).

However, it seems likely that an accidental overdose of approximately 70 times the recommended intake caused the complications (34).

Overall, it appears that methionine is not particularly toxic in healthy humans, except at extremely high doses that would be virtually impossible to obtain through the diet.

Even though methionine is involved in the production of homocysteine, there is no evidence that intake within a typical range is dangerous for heart health (29).

Summary

Individuals following many types of diets will often exceed the recommended minimum intake of methionine. Side effects in response to large doses are often minor but could become dangerous at extremely high doses.

Methionine is a unique sulfur-containing amino acid that can be used to build proteins and produce many molecules in the body.

These include the antioxidant glutathione and the molecule SAM, which is used to modify DNA and other molecules.

Methionine is found in a variety of protein-containing foods and is often higher in animal proteins than plant proteins. Although low-methionine diets have been shown to extend lifespan in animals, whether this has importance for humans is not yet clear.

Individuals consuming many different types of diets typically meet the recommended intake of methionine, although some elderly individuals may benefit from increasing their intake.

Side effects in response to large doses are typically minor but could become dangerous at extremely high doses beyond what could be obtained by a normal diet.

Based on available research in healthy humans, you probably don’t need to specifically limit or increase methionine intake in your diet.

Methionine. Properties, Features, Applications

Methionine

CAS number: 59-51-8
Gross formula: C5h21NO2S
Appearance: white powder with specific odor
Chemical name and synonyms: 900 04 DL-Methionine, DL-2-Amino-4 -(methylthio)butyric acid; Acimetion
Physical and chemical properties:
Molecular weight: 149. 21 g/mol
Density 1.34
Melting point 270-273°C
Boiling point 186°C
pH 5.0-6.5 at 140g/L at 25°C (77°F)
Solubility in water 2.9 g / 100 ml (20 ºC)

Description:

Methionine is an essential amino acid containing a sulfur atom. It is a precursor of cysteine ​​(formed from serine with the participation of methionine as a sulfur-containing amino acid) and taurine (formed from cysteine). One of the most important conversions of methionine is the conversion to S-adenosylmethionine or “SAM”. SAM is involved in many different chemical reactions, transferring part of itself to other molecules, including DNA and proteins. SAM is also used in the production of creatine, an important molecule for cellular energy. Since methionine is metabolized to a wide range of different substances in a number of biochemical reactions, it directly or indirectly participates in many important processes in the body. In addition, methionine plays an important role in the synthesis of other proteins such as carnitine or melatonin.

Methionine in the blood reduces the level of histamine, which in turn reduces the allergic reactions of the body. It has antioxidant and detoxifying properties by binding to free radicals and toxins. Methionine also has a fat-soluble effect and reduces the deposition of fat in the liver. The ability of methionine to acidify urine makes it possible to use it in diseases of the urinary tract and in the formation of kidney stones.

Methionine is an important cartilage-forming substance. Cartilage in the joints requires sulfur. If there is not enough sulfur in the body, it can have negative consequences for a healthy person in the long run. For example, in people with arthritis, the healing process of damaged tissue can be lengthy if there is a sulfur deficiency at the onset of the disease.

Methionine is not synthesized by the body and must be ingested with food. Sources of methionine are animal meat (beef, chicken, etc.), dairy products (yogurt, cheese, etc. ), nuts (high content in Brazil nuts), eggs, legumes, sesame, pumpkin, sunflower seeds, etc.

Application:

Oral methionine is used to prevent liver damage from acetaminophen poisoning and to test people for hyperhomocysteinemia. It is also used orally to lower urine pH, treat liver disease, viral infections including human papillomavirus, herpes simplex virus, and herpes zoster, reduce the risk of colorectal and/or breast cancer, and reduce pain secondary to pancreatitis. Methionine is used orally for neural tube defects, depression, alcoholism, allergies, asthma, copper toxicity, side effects of radiation, schizophrenia, drug withdrawal, postmenopausal conditions including hot flashes, and Parkinson’s disease.

Methionine is a dietary supplement for enriching people’s food, one of the important components in sports nutrition.

Receipt:

The pure method for obtaining D, L-methionine includes the following steps: preparing a potassium cyanide solution using a crystallized mother liquor containing potassium carbonate as an absorbent liquid, then reacting the potassium cyanide solution with 3-methylthiopropionaldehyde and ammonium bicarbonate solution at 50-150 ° C for 3-15 minutes to obtain a solution of 5- (β-methylthioethyl) glycoluria, bringing the solution of 5- (β-methylthioethyl) glycoluria to a temperature of 140-220 ° C and obtain a saponification reaction within 2-5 minutes, after completion saponification temperature reduction to 0-40 ° C, extraction with an organic solvent, neutralization of the aqueous phase with CO 2 , crystallization, then filtration, washing and drying to obtain an acceptable product D, L-methionine; bringing the crystallized mother liquor of D,L-methionine from filtration to a temperature of 110-160°C to remove CO2, which is then circulated and used as hydrocyanic acid absorbing liquid. The technological process of the present invention is a way suitable for continuous and clean production, essentially without the production of waste water and waste gas.

Methionine is also used in veterinary medicine. It is sometimes used as an ingredient in dog food. Methionine may help reduce the chances of stones in dogs. It is permitted as a supplement to organic poultry feed.

Methionine can be used as a non-toxic version of the pesticide against giant swallow caterpillars, which are a serious pest of orange crops.

Action on the body:

The mechanism of the possible antihepatotoxic activity of L-methionine is not entirely clear. It is believed that the metabolism of high doses of acetaminophen in the liver leads to a decrease in glutathione levels and increased oxidative stress. L-methionine is the precursor of L-cysteine. L-cysteine ​​itself may have antioxidant activity. L-cysteine ​​is also a precursor to the antioxidant glutathione. The antioxidant activity of L-methionine and L-methionine metabolites seems to explain its possible antihepatotoxic activity. Recent studies show that methionine itself has free radical scavenging activity due to sulfur as well as its chelating ability.

When metabolized, methionine enters the methionine cycle and is converted to S-adenosylmethionine (SAMe). After the donation of the methyl group, SAMe is hydrolyzed to homocysteine ​​and then either remethylated to methionine or supersaturated, resulting in the formation of cysteine, taurine and glutathione. As an antioxidant, glutathione prevents free radical damage to the liver, and taurine plays a role in bile acid conjugation. Failure to maintain homeostasis of the methionine cycle is believed to result in liver damage. Patients with alcoholic liver disease often have hypermethioninemia, which is thought to be due to a decrease in the metabolism of methionine to SAMe. Low levels of glutathione in the liver increase the risk of free radical damage.

Toxic methionine levels can be corrected with glycine. Glycine appears to enhance the degradation of methionine by transsulfuration by acting as a receptor for methyl groups. Excess methionine competes for glycine and limits the availability of glycine for other metabolic interactions such as glutathione synthesis. In acetaminophen poisoning, methionine appears to prevent liver damage and necrosis by stimulating glutathione synthesis. The toxic metabolite of acetaminophen (N-acetyl-p-benzquinoneimine) will bind to glutathione instead of liver cells.

Dietary methionine does not usually affect homocysteine ​​levels. Levels may rise and possibly cause hyperhomocysteinemia if the enzymes used to metabolize homocysteine ​​are defective and/or there is a deficiency in folic acid, vitamins B6 or B12. Hyperhomocysteinemia can cause damage to the endothelium and increase the risk of developing vascular disease. Hyperhomocysteinemia that does not respond to vitamin supplements sometimes responds to dietary restriction of methionine.

Methionine prevents side effects caused by long-term exposure to nitrous oxide. Nitrous oxide toxicity resembles cobalamin deficiency. Preliminary evidence suggests that nitrous oxide can selectively interfere with cobalamin-dependent methionine synthase function. Administration of methionine prior to surgery may prevent methionine synthase inactivation and prevent cobalamin inactivation in patients undergoing nitrous oxide anesthesia.

Many amino acids are known to stimulate growth hormone. There is preliminary evidence that methionine also enhances basal growth hormone secretion.

Methionine may act synergistically with folate to reduce the risk of colon cancer. However, there is also evidence that a high intake of methionine with salt and nitrates in the diet may increase the risk of stomach cancer. The level of methylation in the tumor is much higher than in normal tissue. Most tumors depend on exogenous, preformed methionine for growth. Preliminary clinical evidence suggests that dietary restriction of methionine in cancer patients may inhibit tumor growth and improve cancer treatment outcomes.

Toxicological data:

Acute Oral LD50 Toxicity – Rat – 3400mg/kg

Description METHIONINE indications, dosages, contraindications of the active substance METHIONINE