Magnesium Explained Simply

1. What Is Magnesium?

Magnesium is a mineral. The body needs it for several hundred enzymes. These enzymes help with energy production, muscle and nerve function and heart rhythm. About half of the magnesium in the body is in the bones. Only a very small part is in the blood.

2. Where Is It Found, and What Is It Made From?

Magnesium is in many foods. Good sources are whole grains, legumes, nuts, seeds and green leafy vegetables. Some mineral waters also contain a lot of magnesium. Supplements contain magnesium as a salt. Examples are citrate, oxide, glycinate, aspartate, chloride, carbonate or L-threonate. The salts differ in how much magnesium they contain and how well they are absorbed and tolerated.

3. What Does Magnesium Do? What Research Shows

Blood Sugar and Metabolism

In type 2 diabetes, oral magnesium salts lowered fasting glucose more than the control 78. In two other reviews, insulin resistance and fasting glucose also decreased 924. In a precursor to diabetes, insulin resistance improved, but fasting glucose did not reliably decrease 17. Two reviews that evaluated magnesium together with other minerals or vitamins found lower fasting glucose in gestational diabetes and polycystic ovary syndrome 1227. The share of magnesium in this cannot be separated.

Blood Pressure, Heart and Blood Vessels

Oral magnesium salts lowered blood pressure in several studies, especially in people with hypertension, diabetes or magnesium deficiency 2578913. In kidney patients, the wall thickness of the carotid artery decreased in two reviews 1420. However, magnesium did not slow vascular calcification in chronic kidney disease 1434. Magnesium did not prevent new-onset atrial fibrillation 4. The results depend on the salt form and the daily amount, and many studies were small or of short duration.

Stress, Anxiety and Mood

People with depression had fewer symptoms with magnesium than with the control. This was shown by a review 19 and three randomized (participants assigned by lot) trials 454955. A study in overweight women with mild to moderate depression found no difference from the control 37. A review also found an improvement in self-reported anxiety, although the studies were inconsistent 26. The studies are often small and differ in salt, dose and population; long-term studies are still pending.

Sleep

In people with sleep problems, sleep was better with magnesium than with a sham. This was shown by two randomized (participants assigned by lot) trials: more deep sleep and REM sleep with magnesium L-threonate 53, longer sleep duration and more deep sleep in the other 52. A review reports better sleep quality with magnesium oxide and vitamin B6 in restless legs syndrome 15. In fibromyalgia, participants slept better with magnesium plus coenzyme Q10 and tryptophan; whether this was better than a sham, the summary does not say 39. Other studies found no difference 3843.

Bones

In chronic kidney disease, magnesium lowered parathyroid hormone and calcium levels in two reviews 1420. In diabetic nephropathy, magnesium citrate lowered the bone turnover marker osteocalcin more than the control in a randomized trial 44. Magnesium oxide did not reliably change another bone resorption marker 47. A randomized trial on bone density gave both groups calcium, magnesium and calcitriol; the benefit there came from red clover extract with probiotics, not from magnesium 41.

Muscles and Muscle Cramps

In nocturnal leg cramps, magnesium oxide reduced the frequency and duration of episodes more than placebo (sham) in a randomized trial 32. In leg cramps, a review found no difference, nor did two randomized trials with magnesium citrate and magnesium hydrochloride 183536. In calf cramps, a randomized trial with magnesium oxide found no reduction 38. In two studies with a comparison group, muscle soreness decreased more with oral magnesium than in the comparison group 5657; a magnesium gel for topical use did not help 51. Muscle strength remained unchanged in three studies with a comparison group 515748.

Headache and Migraine

A review found fewer migraine attacks, lower severity and fewer migraine days with magnesium than with control 25. A systematic review (ordered summary of all studies) rates magnesium as possibly effective for migraine prevention 29. Another review sees evidence that magnesium can prevent and relieve migraine 28. The evidence is low because controlled studies on migraine are missing here; oral magnesium salts were studied. Questions about dose, salt form and duration of intake remain open.

Pregnancy

In gestational diabetes, magnesium lowered fasting glucose and insulin resistance in a review, but preterm births and large newborns were not less frequent 21. A small randomized trial with magnesium oxide found less neonatal jaundice and hospital stays than with placebo, as well as fewer active inflammatory genes 50. The gene expression of IL-1 and VEGF remained unchanged 50. The evidence is low, because there is only one small study with a comparison group.

Other Outcomes

In several controlled trials and reviews, magnesium increased the magnesium level in the blood or urinary excretion 1417313342. The inflammatory marker CRP in the blood decreased more than with placebo in two reviews and two randomized trials 11164248. In a randomized trial in overweight individuals, urinary cortisol also decreased more than with placebo 54. It remains open which salt form and daily amount is most favorable for which measure (measured value).

4. How Was Magnesium Taken in the Studies?

The studies predominantly used oral magnesium salts. These include citrate, oxide, glycinate, aspartate, chloride, L-threonate and hydroxide as well as magnesium-rich mineral water. Individual studies tested magnesium for topical use as a gel or iontophoresis. In combination products with vitamin B6, vitamin D, potassium or other components, the contribution of magnesium cannot be separated.

5. Is Magnesium Safe? Side Effects in the Studies

In the studies, magnesium was predominantly well tolerated. Adverse events were mostly mild and similarly frequent in both groups 313539. In a study with magnesium oxide, however, half of the magnesium group had gastrointestinal changes, compared with only 7% with placebo 46. In chronic kidney disease, more gastrointestinal complaints occurred with magnesium hydroxide than with placebo. In addition, five participants died in this group and six had cardiovascular problems; with placebo, two participants died and there were no cardiovascular problems 34.

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