Magnesium glycinate explained: the form, the math, and what it isn't
Nutriens editors
Magnesium glycinate is magnesium bound to glycine, a small amino acid. It is the form inside Magnesium Foundation, and it is one of the forms people ask about most, often because someone online called it a sleep supplement. This article covers what the form is, how to read its milligrams, how it compares with other forms, and what it isn't.
What magnesium does
Magnesium is a mineral your body uses all day. The NIH Office of Dietary Supplements (ODS) describes it as a helper in more than 300 enzyme systems. It is involved in muscle contraction and relaxation, normal nerve function, energy production, and the building of bone and protein.
Most of it should come from food: leafy greens, beans and lentils, nuts, seeds and whole grains. The ODS also notes that dietary surveys in the United States consistently find many people eating less than the recommended amount. A supplement can help close that gap. It doesn't replace the food.
For adults, the Recommended Dietary Allowance is 310 to 320 mg a day for women and 400 to 420 mg for men. The Daily Value printed on labels is 420 mg.
What "glycinate" means
A capsule can't hold magnesium on its own. It is always bound to a partner: oxide, citrate, chloride, glycinate and others. The partner decides how much of the powder's weight is magnesium and how readily it dissolves.
Glycinate pairs magnesium with glycine. Glycine is heavy compared with magnesium, so most of the weight of magnesium glycinate is glycine, not magnesium. That is the whole reason for the label math below.
A fair note on absorption: the ODS says forms that dissolve well in liquid are absorbed more completely than forms that don't, and small studies found citrate, aspartate, lactate and chloride absorbed better than oxide and sulfate. The fact sheet doesn't rank glycinate in that list, so we won't make a ranking claim for it either.
The label math: 2,500 mg in, 275 mg of magnesium out
Magnesium Foundation's Supplement Facts panel prints two lines. Here is how to read them.
| On the label | What it means |
|---|---|
| Magnesium 275 mg, 65% DV | The magnesium you actually get from one serving. This is the number to compare. |
| from 2,500 mg magnesium glycinate | The weight of the whole compound, glycine included. |
| Serving size 3 capsules | All amounts are per 3 capsules, not per capsule. |
| 30 servings per container | 90 capsules, so one bottle lasts 30 days. |
275 divided by the 420 mg Daily Value is the 65% on the panel. Because 2,500 mg of glycinate is needed to deliver 275 mg of magnesium, the dose takes three capsules. A front label that only says "2,500 mg magnesium glycinate" would be telling you the compound weight, not the magnesium. Our article on elemental magnesium and the milligram on the front walks through that trap with more examples.
Where oxide fits, including in our own multivitamin
Magnesium oxide isn't a bad form. It carries more magnesium per milligram than glycinate, which is why it suits a small base dose inside a multivitamin capsule. Our own Daily Foundation uses it: 50 mg of magnesium as magnesium oxide, 12% of the Daily Value.
What changes with form is the size of the dose and how your gut handles it. The ODS notes that large doses of magnesium from supplements can cause diarrhea, nausea and cramping, especially the carbonate, chloride, gluconate and oxide forms. For a full daily dose on its own, Magnesium Foundation uses glycinate and prints it by name.
What glycinate isn't
It isn't a sleep aid, and Magnesium Foundation has no melatonin. Its label line is "Supports muscle function, eases tension & restores evening calm.*" That is the claim, and there isn't a bigger one hiding behind it.
If you are looking for a sleep formula, that is a different product with different cautions. Rest Balance is the bottle for that: 10 mg of melatonin with a sleep blend that includes St. John’s wort and 5-HTP. Ask your doctor first, especially if you take any medication or are pregnant or nursing, and skip other melatonin products while you take it.
How much magnesium is too much
The ODS sets the adult upper limit for magnesium from supplements and medications at 350 mg a day. Magnesium from food doesn't count toward it, because the kidneys clear extra dietary magnesium.
That makes totals worth checking. Magnesium Foundation gives 275 mg, Daily Foundation 50 mg and Rest Balance 13 mg, and antacids and some laxatives contain magnesium too. If you take any other magnesium, ask your doctor about your total. People with kidney disease should ask before taking magnesium at all, since the ODS notes their risk of too much is higher.
How to take it
Three capsules once a day. The label doesn't set a time; we suggest the evening, tied to something you already do, like brushing your teeth. The step-by-step version is in the Magnesium Foundation evening routine, and the short answers are in the Magnesium Foundation FAQ.
Not sure magnesium is the right place to start? Find your formula takes two minutes, and the daily essentials collection shows the everyday basics side by side.
References
- NIH Office of Dietary Supplements. "Magnesium: Fact Sheet for Health Professionals." ods.od.nih.gov
- Institute of Medicine. Dietary Reference Intakes for Calcium, Phosphorus, Magnesium, Vitamin D, and Fluoride. National Academies Press, 1997.
- U.S. Food and Drug Administration. "Daily Value on the Nutrition and Supplement Facts Labels."
- Magnesium Foundation label: Supplement Facts and suggested use.
