Magnesium
Magnesium is a cofactor for more than 300 enzyme systems that regulate protein synthesis, muscle and nerve function, blood glucose control, and blood pressure. It is needed to produce energy and to build DNA and bone. About half of the body's magnesium is stored in bone, and many people fall short of the recommended intake through diet alone.
Why it matters
What it does in your body
- Cofactor for 300+ enzymes
- Energy (ATP) production
- Muscle and nerve function
- Blood glucose regulation
- Blood pressure regulation
- Bone structure and DNA synthesis
By age, sex, and life stage
How much you need
Values are RDAs except for infants, which are AI values. Adult needs differ by sex (men need more than women) and step up slightly at age 31; pregnancy raises the requirement, but lactation returns it to the nonpregnant level.
Recommended intake across life
in mg/dayBars scale to the highest recommendation shown. Where men and women differ, both values are listed.
Full reference table
| Life stage | Male | Female |
|---|---|---|
| Infants 0-6 mo | 30 (AI) | 30 (AI) |
| Infants 7-12 mo | 75 (AI) | 75 (AI) |
| Children 1-3 | 80 | 80 |
| Children 4-8 | 130 | 130 |
| Children 9-13 | 240 | 240 |
| Teens 14-18 | 410 | 360 |
| Adults 19-30 | 400 | 310 |
| Adults 31+ | 420 | 320 |
| Pregnancy | n/a | 350 to 400 |
| Lactation | n/a | 310 to 360 |
Values in mg/day. AI marks an Adequate Intake, used when there is not enough evidence for a formal recommendation.
What moves the number
What changes your needs
Age
Needs climb through childhood and jump at ages 14 to 18, then rise slightly again at 31; older adults absorb less and excrete more, raising the risk of shortfall.
Sex
Adult men need 400 to 420 mg while women need 310 to 320 mg, reflecting differences in body size and lean mass.
Body weight / size
Larger, more muscular bodies hold more magnesium, which partly explains the higher male requirement; the RDA is set per sex and age band rather than per kilogram.
Pregnancy and lactation
Pregnancy adds about 40 mg to support fetal growth, while lactation returns to the nonpregnant requirement.
Running low
Signs you might not get enough
Most at risk: People with gastrointestinal diseases that impair absorption, those with type 2 diabetes, people with chronic alcohol dependence, and older adults are most at risk of magnesium inadequacy.
Too much
Can you get too much?
Toxicity from food is essentially unknown because the kidneys clear the excess. The danger comes from high-dose supplements and magnesium-containing laxatives or antacids, especially in people with impaired kidney function.
Where to get it
Best food sources
The bottom line
Adult men should target about 400 to 420 mg and women 310 to 320 mg a day, best met with seeds, nuts, legumes, whole grains, and leafy greens. If you supplement, keep added magnesium under 350 mg to avoid diarrhea, since the food supply carries no upper limit.
Track magnesium automatically
Magnesium is one of the 92 nutrients Vora reads from a photo of your meal, so you can see where you stand without weighing or logging by hand.
Sources and method
The recommended intakes, upper limits, and food-source amounts on this page come from the primary references below. Numbers were checked against the current NIH Office of Dietary Supplements fact sheets and the Institute of Medicine (now the National Academies) Dietary Reference Intakes.
- NIH Office of Dietary Supplements, Magnesium Fact Sheet for Health Professionals
- Institute of Medicine (1997), Dietary Reference Intakes for Calcium, Phosphorus, Magnesium, Vitamin D, and Fluoride
This page is for general education, not medical advice. Reference intakes are population averages for healthy people and do not replace guidance from your doctor or a registered dietitian, especially if you are pregnant, managing a health condition, or considering supplements.