Benefits, Side Effects, Dosage, and Interactions

Magnesium oxide is a supplement often used to treat migraine and constipation. It may provide other health benefits, including potentially lowering blood pressure and blood sugar levels.

Magnesium is a mineral that’s needed for many bodily processes, including blood sugar regulation, nerve function, energy production, and DNA synthesis (1).

It’s found in a number of foods but can also be taken as a dietary supplement. These supplements contain different forms of magnesium, including magnesium citrate, magnesium glycinate, and magnesium oxide.

Magnesium oxide is one of the most common forms sold in supplement form, either as a stand-alone supplement or in multinutrient products.

This article explains everything you need to know about magnesium oxide, including how it compares with other forms of magnesium, its potential benefits and side effects, and how to take it.

Magnesium oxide is an inorganic salt of magnesium formed with ions of magnesium and oxygen (2).

It’s one of many forms of magnesium available for purchase in supplement form. It’s added to dietary supplements as well as over-the-counter medications used to treat constipation, indigestion, and headaches.

Compared with other forms of magnesium, it may be less effective at raising blood magnesium levels (3).

How does it compare with other forms of magnesium?

Magnesium oxide and other inorganic salts of magnesium like magnesium carbonate are high in elemental magnesium, which is the total amount of magnesium in a supplement (3).

However, they have a low solubility rate, making them less bioavailable than other forms of the mineral. So, even though magnesium oxide supplements provide a good amount of magnesium, it’s not the most available form for your body to utilize (3).

A 2019 study confirmed this by testing 15 magnesium supplements and finding that a supplement containing only magnesium oxide had the lowest bioavailability (3).

Meanwhile, a supplement with both inorganic and organic magnesium salts — magnesium oxide and magnesium glycerophosphate, respectively — had the highest bioavailability (3).

Because of its low absorption rate in your intestines, magnesium oxide may lead to digestive effects like diarrhea. In fact, its strong laxative effects are why it’s commonly used to treat constipation (3).

A 2017 rat study demonstrated its low absorption rate, concluding that only 15% of orally administered magnesium oxide was absorbed, while 85% was excreted in the feces. Older research suggests the absorption rate is even lower in humans (4, 5).

In contrast, magnesium citrate, magnesium acetyl taurate, magnesium malate, and magnesium glycinate all have high absorption rates and are more effective at increasing magnesium levels in the body (6, 7, 8, 9, 10).

Still, magnesium oxide has been shown to offer several benefits and is commonly used to treat medical conditions like chronic constipation.

Summary

Magnesium oxide is an inorganic salt of magnesium. Even though it contains high amounts of magnesium, it has low absorbability in the body. Still, it has been shown to offer health benefits like constipation relief.

Research shows that magnesium oxide is effective at treating certain medical conditions.

May help treat headaches

Magnesium is needed for proper nerve cell functioning. As such, a deficiency in this mineral can lead to migraine headaches.

Studies show that magnesium oxide may reduce headache symptoms. It may even be as effective as some migraine headache medications (11).

For example, a 2021 randomized, controlled, double-blind study in 63 people who experienced migraine found that taking 500 mg of magnesium oxide daily reduced migraine frequency as effectively as a migraine medication called valproate sodium (12).

Older research also suggests that magnesium oxide may reduce migraine in children (13).

However, other forms of magnesium like magnesium sulfate and magnesium citrate may be more effective at treating migraine, as they are typically better absorbed (14, 15, 16).

May reduce stress and anxiety

Magnesium plays an important role in your body’s stress response. In fact, studies have shown that people who experience frequent stress tend to have lower magnesium stores (17).

Some studies have shown that supplementing with magnesium may help reduce levels of stress and anxiety in certain populations.

For example, a 2017 review of 18 studies found that magnesium oxide may reduce stress and anxiety in women with premenstrual syndrome, but only when combined with vitamin B6 (18).

Despite these promising results, researchers acknowledge that the quality of existing studies on the subject is poor, and future well-designed studies are needed (18).

Helps treat constipation

One of the most common uses of magnesium oxide supplements is constipation treatment. The supplement has an osmotic effect, meaning it draws water into the intestines to cause a laxative effect that can help relieve constipation in both children and adults.

In a small 2019 randomized, double-blind, controlled study, 34 women with mild to moderate constipation were treated with either 1.5 grams of magnesium oxide or a placebo daily for 4 weeks (19).

Many women in the magnesium group experienced significantly improved bowel movement frequency, stool form, colonic transport time, and quality of life compared with the placebo group (19).

In fact, over 70% of those treated with magnesium oxide reported overall symptom improvement, compared with only 25% of those in the placebo group (19).

Similarly, a study in 90 people with constipation found that taking either 1.5 grams of magnesium oxide or 1 gram of senna, another laxative, significantly improved spontaneous bowel movements and constipation-related quality of life compared with a placebo (20).

Magnesium oxide has also been shown to prevent constipation after surgery, treat opioid-induced constipation, and improve functional constipation in children (21).

That said, while magnesium oxide has been shown to be safe for treating constipation, it may lead to dangerously high magnesium levels in certain populations, such as those with kidney impairment and older adults (5).

May lower blood pressure

Magnesium oxide supplements may help reduce elevated blood pressure levels.

A 2018 study in 48 people with high blood pressure found that treatment with 300 mg of magnesium oxide per day for 1 month significantly decreased both systolic (the top number) and diastolic (the bottom number) blood pressure (23).

Researchers theorize that the supplement may lower blood pressure by decreasing cellular calcium levels to relax smooth muscle cells and widen blood vessels (23).

May lower blood sugar levels

Magnesium supplements may lower blood sugar levels in people with diabetes.

For example, supplements containing magnesium oxide and zinc have been shown to lower blood sugar levels in people with type 1 diabetes, type 2 diabetes, and gestational diabetes, which is diabetes that can occur during pregnancy (24).

In a 2015 study, 70 women with gestational diabetes supplemented with either 250 mg of magnesium oxide or a placebo daily for 6 weeks (25).

The magnesium oxide treatment significantly improved blood sugar levels. It also reduced triglyceride levels and the inflammatory markers C-reactive protein (CRP) and malondialdehyde, compared with the placebo group (25).

Magnesium oxide supplements have also been shown to improve blood sugar management in Egyptian children with type 1 diabetes and Iranian adults with type 2 diabetes (26, 27).

Summary

Magnesium oxide may help treat migraine and constipation, reduce blood pressure, improve blood sugar management, and decrease levels of stress and anxiety in certain populations.

While supplementing with magnesium oxide may offer some benefits, there are potential side effects to consider.

Magnesium oxide is generally safe when used in appropriate doses. However, taking large amounts over long periods can lead to high blood magnesium levels, or hypermagnesemia, which is a serious condition that can be fatal (28, 29).

Groups particularly at risk of developing hypermagnesemia include those with kidney disease, older adults with bowel disorders, and those taking 1,000 mg of magnesium oxide or more per day (28, 30).

A 2019 case series discussed four cases of hypermagnesemia, one of which was fatal. All of the patients were over 65 years old and had kidney disease (30).

As such, researchers urge healthcare professionals to be aware of this risk and monitor magnesium levels in those being treated with magnesium oxide and other forms of magnesium (30).

Magnesium oxide may also result in digestive side effects like bloating and diarrhea, especially when taken at higher doses (31, 32).

What’s more, the supplement may suppress the absorption of certain medications, including antipsychotic and antidepressant drugs, as well as those used to treat urinary incontinence and Parkinson’s disease (33, 34, 35).

If you’re interested in taking magnesium oxide, consult your healthcare professional to determine whether it’s appropriate and safe for you.

Summary

High doses of magnesium oxide may cause dangerously high blood magnesium levels, which is more likely in specific populations. It may also cause side effects like bloating and diarrhea and reduce the effectiveness of certain medications.

How much magnesium oxide to take depends on the treatment purpose.

For example, magnesium oxide is used to prevent migraine with daily 500-mg doses (12).

Meanwhile, 300 mg per day has been shown to help treat high blood pressure, while 250 mg per day may help lower blood sugar levels in women with gestational diabetes (23, 25).

Higher doses of the supplement — usually over 1 gram — are used to treat constipation, though daily doses as low as 250 mg may be enough for some people (5).

Summary

Magnesium oxide dosing generally ranges from 250–1,000 mg per day depending on what it’s being used to treat. Taking too much can be dangerous. Speak with your healthcare professional if you have questions regarding dosing or side effects.

Magnesium oxide is a form of magnesium commonly taken as a dietary supplement. It has a lower bioavailability than other forms of magnesium, but it may still offer benefits.

Mainly, it’s used to treat migraine and constipation. It may also help reduce blood pressure, blood sugar, and anxiety in certain populations.

Taking too much magnesium is dangerous and can cause elevated blood magnesium levels, digestive side effects, and hindered absorption of certain medications.

If you’re interested in supplementing with magnesium oxide, consult your healthcare professional first to find out if it’s the right choice for you.

Health Benefits, Nutrients per Serving, Preparation Information, and More

Written by WebMD Editorial Contributors

In this Article

• Benefits of Magnesium Oxide
• Health Risks
• Amounts and Dosage

Magnesium is an important macronutrient, and it is the fourth most abundant positively-charged ion in the body. It is one of the electrolytes that cause muscles to contract, and it helps regulate your nervous system, blood sugar levels, and blood pressure. Your body needs it to complete more than 300 processes involving enzymes and proteins. Sufficient magnesium can usually be obtained through a normal, healthy diet, but low levels of magnesium can lead to serious problems.

There are at least 10 chemical compounds that contain magnesium and can be used as health supplements. Each of these is better suited for some uses than for others. Magnesium oxide is best used for digestive problems and heartburn. Magnesium oxide can also be used to supplement magnesium levels in the body, but it may not work as well as other magnesium compounds that are more readily absorbed into the bloodstream, including those you can get naturally from foods.

Magnesium oxide, often available in capsule form, is commonly used to help a number of concerns, ranging from simple low magnesium levels to more specific concerns, like the following:

Relief of Indigestion and Heartburn

Magnesium oxide may be used as an antacid to relieve indigestion and heartburn.

Relief from Constipation and Irregularity

Magnesium oxide causes the intestines to release water into the stool, which softens the stool and relieves constipation and irregularity. A dose of 250 milligrams can be repeated every 12 hours until you find relief.

Relief from Migraine

Studies have shown that patients with migraine, including cluster headaches and menstrual migraine, often have low levels of magnesium, and taking supplements like magnesium oxide may be helpful. Studies suggest that magnesium ions provided by magnesium oxide interrupt the brain signals that may cause migraine. A dose of 400–500 milligrams per day may be required to be effective. This dose may also cause diarrhea as a side effect, but this can usually be controlled by starting with a smaller dose.

Other Health Benefits

Magnesium offers many other health benefits, but magnesium oxide is not the best source for these benefits. Magnesium oxide has difficulty dissolving in water and is not absorbed into bodily tissues as easily as water-soluble magnesium salts, such as magnesium citrate, magnesium chloride, magnesium lactate, or magnesium malate.

Magnesium oxide is widely used and generally recognized as safe, but it can come with some uncomfortable side effects, such as:

Diarrhea

Because of the same properties that make it a great laxative, even when you’re using it for other health benefits, magnesium oxide can cause cramping or diarrhea.

Flu-like Symptoms

While this is usually not of concern when magnesium oxide is used as a supplement, it is good to be aware that as an industrial chemical, magnesium oxide is recognized as a hazardous substance. Inhalation and prolonged exposure to large amounts of magnesium oxide can irritate the eyes and nose, and can cause flu-like symptoms in some people.

Magnesium is readily available from food, and you can get a good amount from leafy vegetables, nuts, seeds and whole grains. An easy way to remember this is to associate magnesium with fiber. In most cases, foods that are good sources of fiber are also high in magnesium.

The Recommended Dietary Allowance (RDA) for magnesium is 400-420 mg per day for adult men, and 310-320 mg per day for adult women. Women who are pregnant may increase this amount to 350-360 mg per day.

If you are taking magnesium oxide for nutritional purposes, most brands recommend using tablets or capsules, and they suggest taking only 250 milligrams per day. The rest of your magnesium can be obtained from the foods you are eating.

Take capsules or tablets with a full 8 ounce glass of water and with a regular meal.

However, if you are using magnesium as a laxative to relieve occasional constipation or irregularity, you might take it in liquid form, and higher doses may be suggested. Follow the label directions, and do not use it as a laxative for more than 1 week without consulting a doctor.

As with all supplements, you should check with your doctor if you are considering adding magnesium citrate supplements to your diet.

Top Picks

Choosing magnesium together, why is it needed? The benefits of the mineral, its properties

Magnesium is one of the important elements of our body, the deficiency of which leads to serious problems at the cellular level. This is due to the fact that he is directly involved in all biochemical processes, as well as neuromuscular transmission of impulses.

Among the main features of magnesium should be highlighted:

• activation of more than three hundred enzymes;
• ensuring the transportation and further assimilation of B vitamins by the body;
• maintaining the stability of electrolyte balance;
• taking an active part in all types of metabolic metabolic processes, including carbohydrate, protein, fat;
• normalization of blood pressure and providing a vasodilating effect;
• ensuring regular muscle contraction, including the heart muscle.

Magnesium, together with calcium, helps to ensure the normal functioning of the peripheral and central nervous system. These two elements are antagonists, because the first is responsible for inhibition, and the second for accelerating the process of nerve transmission. This creates an ideal balance of synapses.

Important! Leading experts argue that a low concentration of the magnesium element causes chronic inflammation, which accelerates the aging process, increases body weight.

Which foods are rich in magnesium?

You can compensate for the deficiency of the magnesium element by eating certain foods:

Nuts (mg/100 grams):

• cashews – 275;
• cedar – 238;
• almonds – 237;
• pistachios – 205;
• peanuts – 184;
• hazelnuts – 176;
• walnut – 123.

Cereals (mg/100 grams):

• barley – 159;
• buckwheat – 261;
• oatmeal – 144;
• millet – 135.

Legumes (mg/100 grams):

• peas – 109;
• beans (all types) – 106.

Mustard – 238 mg/100g.

Seaweed – 170 mg.

However, despite the rather high content of magnesium in the above products, this does not provide one hundred percent saturation of the body with the necessary amount of nutrients. This is especially pronounced during intense physical activity or strong stress. The best option would be to drink a course of medications and biologically active supplements, the main component of which is magnesium.

People who eat foods high in magnesium (up to 450 milligrams a day) have been able to achieve normal blood pressure readings. Studies have also shown that a person with an average level of blood pressure who takes magnesium-containing drugs has a reduced risk of developing arterial hypertension.

The main benefits of magnesium and its effect on the human body

The main proportion of magnesium is found in the bones, where it affects their growth and maintains health. In addition to the skeletal system, the element is found in muscle and soft tissues, as well as in the extracellular fluid (the percentage of content is not more than 2%). Magnesium in the bones is the main reservoir that ensures the normal concentration of the substance in the blood.

This chemical element is responsible for the synthesis of genetic materials (DNA and RNA), proteins. It also takes part in division, further cell growth, affects productivity and energy conservation. In addition, magnesium is essential for the normal formation of adenosine triphosphate, an energy compound that the body’s cellular system needs.

Main benefits

The main advantages of magnesium are:

1. increasing the efficiency of practicing any kind of sport;
2. struggle with a protracted depressive state. Magnesium plays an important role in brain function. He is responsible for regulating mood, therefore, with a decrease in its concentration, depression occurs;
3. increased action of insulin in the presence of a disease such as type 2 diabetes mellitus;
4. normalization of blood pressure;
5. the presence of anti-inflammatory properties. Magnesium has an anti-inflammatory effect, preventing the development of pathological changes in the human body;
6. reduction of insulin resistance. That is, an increased amount of magnesium indicates a high level of insulin, due to which muscle and liver cells will properly absorb glucose from the blood;
7. migraine prevention.

Interesting! A number of researchers say that people suffering from frequent headaches have very low levels of magnesium. During the experiment, people added 1 gram of magnesium to the diet, and as a result, the number of migraine attacks decreased markedly.

Also, the main benefit of magnesium for girls is to relieve the condition during PMS. Thanks to him, water will not linger in the body, spasms do not occur, fatigue and irritability are eliminated.

How to combine products in order to get the most benefit?

To get the most out of magnesium-containing foods, you need to know what you can pair them with.

Magnesium and vitamin B6	Elements contained in nuts, seeds, are responsible for the regulation of blood pressure, prevent thickening of the vascular walls, the occurrence of arrhythmia, tachycardia and bradycardia. With regards to vitamin B6, it is aimed at enhancing the efficiency of absorption of magnesium by the body. Among the main products that contain these two elements are bananas, raw fruits and vegetables, greens (spinach).
Magnesium and vitamin D	Vitamins regulate blood pressure, normalize the functioning of the heart muscle. Magnesium is combined with vitamin D to form calcitriol. An excellent source of these elements is dairy and seafood, which can be combined with herbs, nuts, legumes.
Magnesium and vitamin B1	This combination activates thiamine and thiamine-dependent coenzymes to help reduce weight.
Magnesium and potassium	Only with the interaction of these elements it is possible to achieve their complete assimilation by the cells of the body. And thanks to their balanced combination, the risk of stroke is reduced. High content of potassium in bananas.

Magnesium is an indispensable electrolyte that is in close interaction with such chemical elements as calcium, potassium, sodium, phosphorus and with a large number of trace elements. It plays an important role for athletes, increasing endurance, being responsible for the rapid recovery of muscles and ligaments. To enhance the effect, zinc-containing products should be consumed.

The concentration of electrolytes in the human body is regulated by hormones produced by the kidneys and adrenal glands. Thanks to sensors in special kidney cells, the amount of useful microelements, as well as water in the blood, is controlled. By the way, they are excreted from the body through the excretory system, including sweat, feces and vomit, as well as urine.

Which magnesium supplements are most beneficial?

The effectiveness of magnesium-containing drugs and biological supplements directly depends on two main points:

• bioavailability, that is, how well the element is absorbed by the body;
• the total amount of “pure” magnesium in the composition.

The higher the bioavailability, the better it will be for the body. All this must be taken into account in order to achieve the desired effect, to prevent the occurrence of side effects, and also not to regret the choice made.

With regards to the total amount of “elemental” magnesium, its volume directly depends on which chemical compound was used by the manufacturer as a source of the element.

It can be:

1. magnesium gluconate – 5.9%. This suggests that for 100 milligrams of magnesium gluconate of a pure element – only 5.8 mg;
2. magnesium chloride – 13%;
3. magnesium citrate – 17.1%;
4. glycinate – 52%;
5. magnesium oxide – 60.8% (highest content).

Based on the above, it becomes clear that it is best to take a drug whose main component is magnesium oxide, because 100 milligrams contains twice as much pure element as 500 mg of magnesium gluconate.

Features of magnesium chelate

Mineral supplement that is associated with amino acids, proteins and participates in their effective, complete assimilation. Chelated dietary supplements are aimed at maintaining the normal functioning of the heart, have a calming effect.

Has a high level of bioavailability. Thanks to this, it is possible to achieve a rapid increase in the amount of magnesium in the human body.

Features of magnesium salts

This form of magnesium acts as minerals or salts that are often found in nature. It is an inorganic additive that is superior to the absorption process of the acid variant.

Interesting to know! Magnesium salts, in high concentration, are found in sea water. The main source is the Zechstein Sea, located in Holland.

The benefits of magnesium in weight loss

Magnesium itself does not have a direct effect on excess weight, but it is not the last part in weight loss, namely:

• has a positive effect on metabolism;
• reduces stress levels by improving the quality of sleep;
• improves the quality of exercise and increases the level of endurance;
• fights inflammation;
• improves mood.

Magnesium Benefits in the Cosmetic Industry

Magnesium oxide is often found in facial skin care products, including serums, lotions, emulsions. It features absorption and matting properties. In addition, it reduces acne, eliminates inflammatory foci, manifestations of allergic reactions, and also controls the amount of collagen.

Magnesium deficiency causes a decrease in the level of fatty acids on the surface of the skin, thereby reducing its elasticity and increasing dryness. As a result, tone is lost, wrinkles appear. That is why it is very important to take supplements containing magnesium, as well as to add appropriate foods to the diet.

Summing up

Magnesium is the most important intracellular element of every cell, tissue. It plays an important role in the ion balance of fluids in the body, and also takes part in a large number of reactions associated with fermentation.

In addition, magnesium is responsible for:

1. energy storage, transfer, utilization;
2. conduction of neuromuscular impulses;
3. inhibition of the processes of excitability of the central nervous system;
4. protein synthesis, nucleic acid.

Product Comparison Table

Product		Dosage	Portion	Release form
	Magnesium Citrate, Now Foods	400 mg	3 capsules	Vegetarian capsule
	Magnesium citrate, Thorne Research	135 mg	1 capsule	Capsule
	100% Chelated Digestible Magnesium Powder with Albion Minerals, Peach Flavor, Doctor’s Best	200 mg	1 scoop (~4 g)	Powder
	Liquid Magnesium Chloride, Nutricology	66. 5 mg	1/2 teaspoon (2.5 ml)	Fluid
	Magnesium with Vitamin B6, Solgar	400 mg	3 tablets	Tablet

Disclaimer

We would like to draw your attention to the fact that the information provided is for guidance only and does not call for the use of magnesium-containing drugs and food products for the treatment and prevention of diseases. Your attending physician should deal with the diagnosis, as well as the appointment of exact dosages. If you notice any pathological changes in yourself, it would be best to seek help from competent specialists.

Oral bioavailability of magnesium oxide and other compounds (review) | Barsuk A.L.

Magnesium oxide is a chemical compound with the formula MgO, white crystals, insoluble in water, fire and explosion proof. In medicine, it is used as an antacid and a source of magnesium. In the food industry, E530 is registered as a food additive as a pH regulator. MgO contains the largest amount of elemental magnesium among all compounds of this metal. Magnesium oxide is an inorganic compound, this group also includes magnesium hydroxide, sulfate, chloride. Along with them, organic compounds are used as a source of magnesium (Mg): pidolate, citrate, gluconate, aspartate, ascorbate, salicylate, and magnesium orotate [1].

To date, there is no clear evidence of the superiority of any oral magnesium preparation. Absorption from the gastrointestinal tract and other pharmacokinetic parameters of oral magnesium compounds are of key importance in predicting the effectiveness of these drugs as a source of magnesium.

There is a widespread opinion that organic magnesium compounds are better absorbed from the gastrointestinal tract than inorganic ones [1–3], however, the results of the studies carried out do not always confirm this point of view [4, 5], and the confirmatory ones are sometimes carried out not quite correctly. For example, in a domestic study, the dynamics of magnesium concentration in blood plasma and erythrocytes was studied after a single administration of various dosage forms of magnesium preparations. The study had a crossover design. It was attended by 16 volunteers (11 men and 5 women). Volunteers participated in the experiment repeatedly, between studies with the participation of the same volunteer there was a gap of at least 15 days. Participants received Magne B6 8 tablets each (Mg lactate dihydrate + pyridoxine, 384 mg calculated as pure Mg), Magne B6 3 ampoules each (Mg lactate dihydrate + Mg pidolate + pyridoxine, 300 mg Mg). The reference drug Berocca Plus was prescribed, according to the instructions, 1 tablet per day (Mg sulfate and carbonate, 100 mg Mg). Bioavailability was assessed as area under the curve in plasma and erythrocytes. Differences in bioavailability between Magne B6 preparations and controls were statistically significant. The authors note a significantly higher bioavailability of organic magnesium in the form of both forms of Magne B6 compared to the reference drug Berocca Plus. Surprisingly, the authors compare the areas under the curve of preparations in which the magnesium content differs by at least 3 times [6].

It should be noted that, despite the active interest in the role of magnesium in metabolic processes, the effect of magnesium deficiency on the development of neurological and cardiovascular pathology, pathology of pregnancy, etc., studies studying the pharmacokinetics of oral magnesium preparations, including and its oxide is very small [1].

In 1973 D.A. Cook published the results of a large experimental pharmacokinetic study of oral inorganic magnesium compounds in rats. After 5 days of low magnesium diets, the animals were fed for 14 weeks. magnesium in the form of magnesium oxide or chloride, or carbonate, or bicarbonate, or phosphate, or sulfate or silicate, or remained on a depleted diet. After that, the animals were slaughtered and using the spectrophotometric method, the levels of calcium and magnesium in the femurs, kidneys, urine, plasma, feces were analyzed, then the absorption of magnesium was calculated: for carbonate, it turned out to be 64. 9%; for chloride – 61%, for oxide – 58%, for phosphate – 54.1%, for sulfate – 53.3%, for silicate – 54.2% [7].

In 1990 J.S. Lindberg et al. conducted an in vitro and in vivo study to compare oral absorption of magnesium oxide and magnesium citrate in humans. The solubility of 25 mmol of both substances in 300 ml of hydrochloric acid solutions of different concentrations (0–24.2 mEq) and distilled water was compared. Magnesium oxide is practically insoluble in water and only 43% soluble in the most concentrated acid solution. Magnesium citrate in distilled water had a solubility of 55% and was better soluble than oxide in acid solutions. When the pH of the solutions was restored to 7 by titration with hydrocarbonate, neither citrate nor oxide recrystallized. Healthy volunteers received 25 mmol of either citrate or magnesium oxide orally. Changes in urinary excretion of magnesium were used to judge the level of salt absorption. The increase in urinary magnesium levels was significantly higher in the group of volunteers treated with citrate [8].

In 1990, T. Bohmer et al. published the results of a study of magnesium excretion in healthy young female volunteers (student) within 24 hours after the use of magnesium in the form of hydroxide, citrate, magnesium lactate or placebo 3 times / day at a daily dose of 15–20.6 mmol. All formulations significantly increased urinary magnesium excretion, but there were no statistical differences in urinary excretion between participants taking different magnesium formulations. However, it should be noted that only 18 people took part in the study [9].

In 1994 S.A. Schuette et al. published data on the intestinal absorption of magnesium oxide and chelated magnesium diglycinate, labeled with the isotope 26Mg, in patients (12 people) who underwent resection of the ileum. The study was a double-blind, crossover design, 100 mg dose. Magnesium oxide and diglycinate showed bioavailability of 22.8% and 23.5%, respectively, but there was a trend towards higher diglycinate absorption in the 4 patients who had the worst oxide absorption. In addition, the peak plasma concentration of the isotope after taking diglycinate occurred earlier by 3.2±1.3 hours [10]. A.F. Walker et al. (2003) studied the comparative pharmacokinetics of magnesium compounds (oxide, citrate and magnesium amino acid chelate (AAC) in healthy volunteers in a double-blind, randomized, placebo-controlled study. Volunteers without signs of magnesium deficiency were randomized into 5 groups: receiving Magnesium oxide 300 mg/day Magnesium citrate 300 mg/day Mg AAS and 2 placebo groups: one received cellulose, the other sorbitol The drugs were taken for 60 days, patients were examined after the first day of administration and after 60 days of treatment.Magnesium levels in blood (plasma and erythrocytes), urine and saliva were studied using atomic absorption spectrophotometry.Interestingly, in all groups, the initial average plasma magnesium levels were below normal.In blood plasma, citrate turned out to be the most effective.It significantly increased magnesium levels compared with AAS after 60 days of therapy, however, there was no statistical difference between the results in the citrate and oxide groups. In this study, only the citrate group significantly increased magnesium levels in saliva. There were no differences between the groups in the level of magnesium in erythrocytes. The researchers note that, theoretically, magnesium oxide should cause a laxative effect, but the participants in the experiment who received it did not notice such an effect of the drug [11].

C. Coudray et al. (2005) using a series of tests, the intestinal absorption and elimination with urine, as well as the accumulation in the body of male Wistar rats of various magnesium compounds, were investigated. The rats received magnesium oxide, or magnesium chloride, or sulfate, or carbonate, or acetate, or pidolate, or gluconate, or citrate, or lactate, or aspartate. Before the study for 3 weeks. the rats received a reduced magnesium diet (150 mg/kg). Then the rats in all groups received the same amount of magnesium in the form of its various compounds (550 mg/kg of body weight). The experiment was continued up to 6 weeks, and then the animals were sacrificed and the magnesium content in plasma, erythrocytes and bones was measured using an accurate method – inductively coupled plasma mass spectrometry. Plasma levels of magnesium, its content in erythrocytes and bones after the use of different salts did not show significant differences with a tendency to superiority with the use of magnesium gluconate. Finally, fecal and urinary excretion of magnesium was studied and absorption of magnesium from the gut was calculated. The results demonstrate the lag of inorganic magnesium compounds (among them, magnesium oxide and chloride are better absorbed – 48.4% and 48.8%, respectively, sulfate is the worst – only 34.8%), and among organic salts, gluconate again holds the record – 56.8% .

The authors conclude that with a slight superiority of organic magnesium compounds (especially magnesium gluconate) and some lagging behind magnesium sulfate, all magnesium compounds are able to be absorbed and affect its levels in the blood and tissues [5].

In 2006, the results of a domestic study were published in the journal “Questions of Nutrition” [Konyukhova O.S. et al.] pharmacokinetics of magnesium and vitamin preparations, conducted with the participation of 60 volunteers, of which 15 once orally received magnesium-containing preparations Magnerot (500 mg of magnesium orotate; in terms of Mg2+ – 32. 8 mg) and another 15 people – Centrum (100 magnesium oxide; in terms of Mg – 60.3 mg). Based on the results of the study, the authors note that when taking the studied magnesium preparations in the body, an equal increase in the concentration of this element occurs in the body, but when magnesium oxide is taken, it occurs at a later date [4].

The purpose of the study, conducted on the basis of the Volgograd State Medical University [Spasov A.A. et al., 2010], there was a comparison of the rate of compensation of alimentary magnesium deficiency (Mg after the introduction of 8 inorganic and 12 organic magnesium salts), as well as an assessment of the ability of vitamin B6 to accelerate the compensation of magnesium deficiency when combined with magnesium salts. To develop magnesium deficiency, 280 rats received a magnesium-deficient diet (magnesium content not more than 15 mg/kg) and distilled water for 7 weeks. A group of intact rats (12 animals) received a magnesium-balanced diet (Mg content – 500 mg per 1 kg of diet). Starting from 49On the diet day, the animals received magnesium salts (Mg chloride, Mg sulfate, Mg oxide, Mg nitrate, Mg thiosulfate, Mg hydrogen phosphate, Mg carbonate, Mg trisilicate, Mg L-, D- and DL-aspartate, Mg L-, and DL -pyroglutamate, Mg succinate, Mg glycinate, Mg orotate, Mg taurinate, Mg lactate) or their combination with vitamin B6 at a dose of 50 mg of elemental magnesium and 5 mg of vitamin B6 per 1 kg of body weight. It was found that magnesium L-asparaginate most effectively and quickly compensates for magnesium deficiency in comparison with all its other salts. Among the inorganic magnesium salts, chloride was the leader in terms of the rate of compensation for magnesium deficiency, and the effectiveness of chloride followed immediately after L-aspartate, ahead of other organic and inorganic salts. The efficiency of the oxide was not inferior to either lactate or magnesium orotate [13].

The study of the bioavailability of magnesium preparations when taken orally continues. In Israel, at the Medical Center. Chaima Shiba recently conducted a comprehensive comparative study of two compounds: magnesium oxide and magnesium citrate. Under observation were 41 healthy volunteers who did not have diagnosed heart disease. They were randomly distributed into two groups. For one month, in each group, the subjects received one of two drugs available on the Israeli pharmaceutical market: magnesium citrate under the commercial name Magnesium Diasporal (295.8 mg of magnesium in one tablet) or magnesium oxide monohydrate under the trade name Magnox 520. study, volunteers started taking magnesium supplements again, but each volunteer was already receiving a second drug for him: that is, those who received magnesium citrate first, this time took magnesium oxide, and vice versa. Before the start of each monthly drug intake and at its completion, magnesium concentrations in the blood serum and in the cells of the tissues of the volunteer’s body were studied, platelet activity, electrolyte concentrations in the blood serum were studied. Volunteers were asked to complete questionnaires regarding the quality of their daily lives. It was found that the intake of magnesium oxide significantly increased the concentration of magnesium in the cells of the body, led to a decrease in the concentrations of low-density cholesterol and C-reactive protein. At the same time, the intake of magnesium citrate did not lead to such positive changes in laboratory parameters. The functional activity of platelets improved under the influence of both drugs [14].

Thus, the results of a few pharmacokinetic studies that determine the absorption of various magnesium salts from the gastrointestinal tract demonstrate a number of factors hindering the study of intestinal absorption of magnesium preparations.

Most of the studies of the pharmacokinetics of magnesium compounds consisted in the study of the level of urinary excretion of magnesium during the day and / or the concentration in plasma / serum of magnesium ions, which makes it possible only for an approximate assessment of the intestinal absorption of magnesium. It must be remembered, however, that plasma magnesium levels are subject to homeostatic control and that magnesium can easily leave the plasma to organs and tissues, and that plasma concentration is not an accurate indicator of intestinal absorption of magnesium. Moreover, the level of magnesium in the blood serum can remain within normal limits even with a decrease in the total amount of magnesium in the body by 80% due to the release of the trace element from the depot [15]. It can be said that so far there is no single generally accepted methodology for studying the effect of magnesium preparations on its content in the human body, and this makes it very difficult to study any pharmacokinetic parameters of these compounds. In addition, a rather limited number of participants in studies of the pharmacokinetics of magnesium preparations in humans and conflicting results attract attention.

Some authors consider it most correct to study the level of magnesium in erythrocytes and/or lymphocytes, as well as its concentration in saliva, but there is no consensus on this issue [5, 16, 17].

Based on the mechanisms of magnesium absorption in the intestine (passive diffusion along the electrochemical concentration gradient), it can be assumed that the lower the solubility, the better the absorption in the gastrointestinal tract. But the results of comparative studies indicate that the bioavailability outsider is not magnesium oxide (which is practically insoluble), but sulfate, which has good solubility (33.7 g in 100 g of water at 20°C) [5, 13].

Magnesium oxide, like other magnesium compounds, has proved in experimental studies the ability to successfully stop the deficiency of this element. Unfortunately, the above difficulties in assessing the bioavailability of magnesium compounds hinder the development of a methodology for such studies. It is especially difficult to study the pharmacokinetics of magnesium compounds in humans. Modeling a deep magnesium deficiency, studying the level of magnesium in bones and other tissues, which have proven themselves in the experiment, are not applicable here.