Quick answer

Women need 310 to 320 mg of magnesium a day from all sources, 350 to 360 mg during pregnancy, and teenage girls 360 mg. Citrate is one of the better absorbed forms, but every form counts by its magnesium content. Supplements should stay at or under 350 mg a day, in pregnancy too, unless a doctor advises more.^1,2,3

Key facts

Women who did not take supplements averaged 234 mg of magnesium a day from food in national survey data.²
Teenage girls are among the groups most likely to get too little magnesium from their diets.¹
Breastfeeding does not raise the amount: adult women need 310 to 320 mg either way.¹
Of the 153 adults analyzed in the bisglycinate sleep trial, 122 were women.⁴

How much women need, by life stage

Magnesium for girls and women, per day²
Life stage	Recommended, all sources	Limit from supplements and medicines
Girls 9 to 13	240 mg	350 mg
Teens 14 to 18	360 mg	350 mg
Women 19 to 30	310 mg	350 mg
Women 31 to 50	320 mg	350 mg
Women 51 and older	320 mg	350 mg
Pregnant, 14 to 18	400 mg	350 mg
Pregnant, 19 to 30	350 mg	350 mg
Pregnant, 31 to 50	360 mg	350 mg
Breastfeeding, 14 to 18	360 mg	350 mg
Breastfeeding, 19 to 30	310 mg	350 mg
Breastfeeding, 31 to 50	320 mg	350 mg

The two columns measure different things. The first counts food, drinks and supplements together. The second counts only what comes from supplements and medicines, which is why a pregnant teen's need can sit above her supplement limit.¹

Do women get enough?

In national survey data from 2003 to 2006, women who did not take magnesium supplements got an average of 234 mg a day from food. Women who took them got 267 mg from food and 387 mg in total.²

That food-only average of 234 mg sits well below the 310 to 320 mg recommended for adult women.²

Men older than 70 and teenage girls and boys are the most likely to get too little magnesium from their diets.^1,2

NIH notes that supplements can be useful when needs are hard to meet from food, for example during life stages such as pregnancy.¹

What the evidence shows for women

The graded claims below come from studies of adults in general, not of women alone. The sleep trial is the exception that comes closest, because most of its participants were women.⁴

Helps you reach the recommended daily magnesium intake*²

Moderate evidence

National survey data from 2013 to 2016 show that 48% of Americans take in less magnesium from food and drink than the estimated average requirement. One serving supplies 275 mg, 65% of the Daily Value. In an earlier national survey, adults who used magnesium supplements had average total intakes well above requirement levels.

Amount studied: Recommended intake: 400 to 420 mg a day for men, 310 to 320 mg for women, from all sources

Contributes to the normal structure of bone*^1,2

Moderate evidence

A long-established role of the mineral, described by NIH: half or more of the body's magnesium is held in bone, where it is part of the bone's structure and takes part in bone formation. This is a role of the nutrient. NIH describes the trials of whether extra magnesium changes bone density as few and small, and says more research is needed.

Amount studied: Recommended daily intake from food and supplements

Most people in the bisglycinate sleep trial were women: 122 of the 153 analyzed. Pregnant and breastfeeding women were not included.⁴

May modestly improve self-rated sleep in adults who sleep poorly*^4,5

Early evidence

One randomized, placebo-controlled trial tested this form: 155 adults who slept poorly took magnesium bisglycinate (250 mg of magnesium a day) or placebo for four weeks. Scores on a sleep-problem questionnaire fell a little more with magnesium (3.9 points against 2.3), a small effect, and other measures did not differ. It is a single short trial that relied on self-report. Older trials used other forms at higher doses in older adults and were rated low quality.

Amount studied: 250 mg a day as bisglycinate, 30 to 60 minutes before bed, for four weeks

Magnesium and bone

An adult body holds about 25 g of magnesium. Half to 60% of it is in bone and most of the rest in soft tissue; less than 1% is in blood serum.²

Magnesium takes part in bone formation and affects the levels of parathyroid hormone and the active form of vitamin D, the main regulators of bone.²

NIH describes the studies of extra magnesium and bone density in women after menopause as few and small, and says more research is needed. NIH also notes that the gut absorbs less magnesium with age, one reason older adults are more likely to run short.^1,2

Which form

We found no study comparing forms in women specifically. Citrate dissolves well and was absorbed better than oxide in small studies. Bisglycinate is the form used in the sleep trial. Oxide is about 60% magnesium by weight, but little of it is absorbed.^3,4,6,7,8

What's in ours

What’s in ours

Magnesium Glycinate: Magnesium, 275 mg per serving, from the label
Men's Multi: Magnesium, 50 mg per serving, from the label
Creatine + Electrolytes: Magnesium, 60 mg per serving, from the label

Pregnancy, breastfeeding and medicines

Needs rise by about 40 mg a day in pregnancy, while the 350 mg limit for supplements and medicines stays the same. Check whether a prenatal vitamin already contains magnesium, and ask your doctor or midwife before adding more.²

For leg cramps in pregnancy, a Cochrane review found the five trials conflicting and all at high risk of bias. The sleep trial left out pregnant and breastfeeding women.^4,9

Ask your pharmacist how far apart to take them

Supplements and medicines rich in magnesium can reduce the absorption of oral bisphosphonates such as alendronate. The alendronate label says calcium, antacids and oral medicines containing minerals such as magnesium interfere with its absorption.^1,2,10

On the medicine's label

Ask your pharmacist how far apart to take them

The levothyroxine label lists antacids, such as those made with aluminum and magnesium hydroxides, among products that may reduce levothyroxine absorption by lowering stomach acid. In a small 2025 study, magnesium aspartate taken at the same time lowered levothyroxine absorption by 12%, and magnesium citrate by 7%, a drop too small to rule out chance.^11,12,13

On the medicine's label

Ask first if you are pregnant or breastfeeding
Ask first if you take a bisphosphonate for osteoporosis, levothyroxine for an underactive thyroid, or a diuretic¹
Ask first if you have kidney disease or reduced kidney function

Questions people ask

Should women take magnesium citrate or glycinate?

Either counts toward the same daily amount. Citrate has more absorption data, and bisglycinate is the form tested in the sleep trial, whose participants were mostly women.^3,4,6

How much magnesium should a woman over 50 take?

320 mg a day from all sources, the same as from age 31, with no more than 350 mg from supplements and medicines. The gut absorbs less magnesium with age.²

Can I take magnesium while pregnant?

You need a little more magnesium in pregnancy, but ask your doctor or midwife before adding a supplement, and keep supplements and medicines at or under 350 mg a day.¹

See what we make

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See the Full Measure line Creatine + Electrolytes Magnesium Glycinate Men's Multi

Sources

*These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.

This page is information, not medical advice. Talk to your doctor or pharmacist about your own situation.