Minerals

Magnesium

Also known as: Mg, Magnesium glycinate, Magnesium citrate

An essential mineral involved in more than 300 enzyme reactions, widely supplemented for sleep, muscle, and nerve function.

By IngredientWiki Editorial Team
Fact-checked by IngredientWiki Editorial Team
Updated 2026-09-25
3 min read

In short

Magnesium is an essential mineral that acts as a cofactor in more than 300 enzyme systems, including energy production, protein synthesis, muscle and nerve function, and blood pressure regulation. Many Americans do not get the recommended amount from food, which is why magnesium is one of the most popular dietary supplements in the United States.

Cofactor in more than 300 enzyme systems in the body
Found in leafy greens, nuts, seeds, legumes, and whole grains
Recommended intake: 400–420 mg daily for men, 310–320 mg for women
Supplement forms vary in absorption and laxative effect

What is Magnesium?

Magnesium is the fourth most abundant mineral in the human body. About half is stored in bone, and the rest is in muscles, soft tissues, and a small but tightly regulated amount in blood. It is needed for energy production (ATP), DNA and RNA synthesis, muscle contraction, and nerve signaling. Because refined Western diets tend to be low in magnesium-rich foods, surveys consistently estimate that many Americans consume less than the recommended amount, making magnesium supplements a staple of the supplement market.

Where it comes from

Natural sources

Leafy green vegetables such as spinach
Nuts and seeds, especially pumpkin seeds and almonds
Legumes, beans, and whole grains
Dark chocolate and some mineral waters

How it's made

Supplemental magnesium is mined or extracted and combined with other molecules (glycine, citric acid, etc.) to form salts with different absorption profiles.

What it does in products

Benefits

Correcting deficiency and inadequate intake

strong evidence

Low magnesium intake is associated with a higher risk of hypertension, type 2 diabetes, and osteoporosis. Supplementation reliably raises blood magnesium in people with low intake.

Constipation relief

strong evidence

Magnesium oxide and citrate draw water into the intestines, acting as osmotic laxatives. Magnesium citrate and hydroxide solutions are used medically for occasional constipation.

Sleep support

moderate evidence

Magnesium is involved in nervous-system calming, and some small trials suggest supplementation modestly improves sleep quality, particularly in older adults and people with low intake.

Muscle cramps and recovery

moderate evidence

Many athletes take magnesium for cramps. Evidence is mixed, but some studies find benefit for nocturnal leg cramps in pregnancy and for people with true deficiency.

Side effects & safety

Loose stools or diarrhea (common)Most common with magnesium oxide and high-dose citrate; switching to glycinate or malate usually resolves it.

Stomach upset and nausea at high doses (uncommon)Taking magnesium with food reduces gastrointestinal discomfort.

Hypermagnesemia from excessive supplementation (rare)Serious toxicity is rare in people with healthy kidneys, which excrete excess magnesium efficiently.

Safety considerations

Magnesium is safe in pregnancy at standard supplement doses and is used to treat preeclampsia in medical settings. Stay within the 350 mg supplement upper limit unless advised otherwise.
Magnesium can reduce absorption of certain antibiotics (tetracyclines, quinolones); separate doses by at least 2 hours.
It can also reduce absorption of bisphosphonates used for osteoporosis; take these well apart.
Not for: Advanced kidney disease (magnesium can accumulate when kidneys cannot excrete it)

How it's used

In supplements

The RDA is 400–420 mg per day for adult men and 310–320 mg for women. The upper limit applies only to supplements: 350 mg per day. Common supplement doses are 200–400 mg daily, ideally in a form matched to your goal: glycinate for general use and sleep, citrate for regularity, malate for energy, and L-threonate for cognition.

Regulatory status

Dietary supplement regulated by the FDA under DSHEA. Manufacturers are responsible for safety and accurate labeling; no pre-market approval is required.
GRAS (generally recognized as safe) for food use.

Choosing a magnesium form

Magnesium is always sold as a salt — the mineral bound to another molecule. The binding molecule affects absorption, tolerated dose, and side effects. Glycinate is well absorbed and gentle on the stomach, making it a common default. Citrate is well absorbed and has a mild laxative effect. Oxide is cheap and contains the most elemental magnesium per gram, but is poorly absorbed and used mainly as a laxative. L-threonate is marketed for brain health and crosses the blood-brain barrier more readily in animal studies, though it is more expensive.

Common magnesium forms compared
Form	Elemental Mg	Absorption	Typical use
Glycinate	~14%	High	General use, sleep, muscle
Citrate	~16%	High	Regularity, general use
Oxide	~60%	Low	Laxative, heartburn relief
L-threonate	~8%	High	Cognition-focused products

Frequently asked questions

Which magnesium is best for sleep?

Magnesium glycinate is the most common choice for sleep support because it is well absorbed and unlikely to cause diarrhea. Evidence for a sleep benefit is modest but the risk is low; many people also pair it with glycine, which may independently support relaxation.

Can I take magnesium every day?

Yes. For most adults, 200–350 mg daily from supplements is safe long-term. Keep total supplement intake at or below 350 mg unless a healthcare provider recommends more, and reduce the dose if you develop loose stools.

Does magnesium interfere with medications?

It can. Magnesium can reduce the absorption of certain antibiotics and osteoporosis drugs, so take those medications at least 2 hours apart from magnesium. If you take diuretics, heart medication, or have kidney disease, check with your doctor first.

The bottom line

Magnesium is a safe, well-studied mineral with broad roles in the body. The clearest reasons to supplement are low dietary intake and constipation; the evidence for sleep and cramp benefits is moderate but positive in some groups. Choose a form that matches your goal and keep supplement doses at or below 350 mg daily.

References

Magnesium — Health Professional Fact Sheet. NIH Office of Dietary Supplements. https://ods.od.nih.gov/factsheets/Magnesium-HealthProfessional/
Magnesium — Consumer Fact Sheet. NIH Office of Dietary Supplements. https://ods.od.nih.gov/factsheets/Magnesium-Consumer/
Magnesium compound summary. PubChem (National Library of Medicine). https://pubchem.ncbi.nlm.nih.gov/compound/5462224
Magnesium deficiency. StatPearls (National Library of Medicine). https://www.ncbi.nlm.nih.gov/books/NBK500004/