A man needs 400 mg of magnesium a day at 19 to 30 and 420 mg from 31 on, counted across food, drink, supplements and medicines, according to the NIH Office of Dietary Supplements. Supplements and medicines should stay at or under 350 mg, the tolerable upper intake level, which does not count food. So at least 70 mg of the 420 has to come from food, and in practice most of it does.
Two numbers, two different totals. The allowance counts everything a man swallows; the ceiling counts only what comes out of a bottle. Most magnesium confusion comes from reading one against the other.
How much magnesium does a man need per day?
The RDA is 400 mg a day for men aged 19 to 30 and 420 mg from 31 onward, with no further change at 51 or 71, according to the NIH Office of Dietary Supplements, working from the 1997 Institute of Medicine report. It counts every source, food and drink included. It sits above the estimated average requirement, 330 mg at 19 to 30 and 350 mg from 31, because it is set to cover nearly all men rather than the average man.
| Age | Estimated average requirement | RDA, all sources | Upper level, supplements and medicines only |
|---|---|---|---|
| 9–13 | 200 mg | 240 mg | 350 mg |
| 14–18 | 340 mg | 410 mg | 350 mg |
| 19–30 | 330 mg | 400 mg | 350 mg |
| 31–50 | 350 mg | 420 mg | 350 mg |
| 51–70 | 350 mg | 420 mg | 350 mg |
| 71 and over | 350 mg | 420 mg | 350 mg |
All three columns are the Institute of Medicine's 1997 values; the Office of Dietary Supplements reproduces the RDA and upper-level columns. The RDA column is the one to plan a diet around; the requirement column is the yardstick for judging a group, which matters below; the upper-level column is a different kind of number altogether, and the next question is about it. The adult figures rest on balance studies, which compare what people take in with what they lose. For men over 70 the report adds intracellular studies and the fall in absorption with age.
One more number sits on every label. The Daily Value for magnesium is 420 mg for adults and children 4 and over, per the Office of Dietary Supplements, the same figure as the RDA for men over 30, so a panel's "% DV" for magnesium reads directly against that allowance. What a panel's other columns mean is in the supplement label glossary.
Is 400 mg of magnesium a day too much?
Not as a total from all sources: 400 mg is the RDA for men aged 19 to 30, and the RDA for men over 30 is 420 mg. As a supplement dose on top of food, 400 mg is above the 350 mg tolerable upper intake level, which counts supplements and medicines only. The same 400 mg is unremarkable from food and over the line from capsules, because the limit was never set on food.
The Institute of Medicine wrote the scope into the limit itself: it "represents intake from pharmacological agents only and does not include intake from food and water." The endpoint was gastrointestinal. Costello and colleagues (Advances in Nutrition, 2023) record that diarrhoea was the basis for the 350 mg figure, which is why the line sits on supplements and medicines, the sources that deliver a large dose of a salt to the gut at once.
The figure is also contested. Costello and colleagues reviewed intervention trials from 1997 to 2022 and found that most reported no significant difference in diarrhoea between magnesium and control groups, and they argue that the American limit should be re-evaluated. All four authors work with a magnesium research and education centre, and their paper is a proposal, not a revision. The published American limit is 350 mg, and every figure on this page is counted against it. What happens near and above that line is in can you take too much magnesium.
How much magnesium should a man take as a supplement?
Only enough to close the gap between his diet and the RDA, and never more than 350 mg a day from all supplements and medicines combined. Against the 420 mg RDA, men over 30 eating the national average for their age fall short by roughly 60 to 100 mg, on the USDA's most recent survey tables. That is the size of the gap a supplement is for. Every magnesium-containing product counts toward the 350 mg: multivitamins, electrolyte mixes, antacids and laxatives included.
The counting is where stacks go wrong, so here is a worked example with invented products. A multivitamin declaring 100 mg of magnesium, a dedicated magnesium capsule declaring 250 mg and an electrolyte powder declaring 60 mg add up to 410 mg of supplemental magnesium — 60 mg over the line, from three products of which only one is sold as magnesium. The figure to add is always the elemental one on each Supplement Facts panel, never a compound weight; the difference between the two is set out in how to read an elemental magnesium label.
Form matters for how a dose is tolerated, not for how it is counted. A milligram of magnesium from citrate, glycinate, chloride or malate counts the same against 350 mg. How those forms differ is set out in glycinate against citrate, glycinate against malate and chloride against glycinate, and across every common form in supplement forms compared.
Do most men get enough magnesium from food?
Many do not. The NIH Office of Dietary Supplements reports that 48% of Americans of all ages took in less magnesium from food and beverages than their estimated average requirement in NHANES 2013–2016, with men aged 71 and older among the groups most likely to fall short. In NHANES 2003–2006, men who did not use magnesium supplements averaged 268 mg a day from food. These are population intake figures, not a measurement of any one man's magnesium.
The newest national averages cover all men, supplement users or not. The USDA's What We Eat in America tables for 2017 to March 2020 put the average intake from food and drink for men aged 20 and over at 339 mg a day.
| Men, age | Average intake from food and drink |
|---|---|
| 20–29 | 312 mg |
| 30–39 | 356 mg |
| 40–49 | 352 mg |
| 50–59 | 357 mg |
| 60–69 | 335 mg |
| 70 and over | 321 mg |
| 20 and over | 339 mg |
Read the table with one caution. An average set against the RDA overstates the shortfall, because the RDA is deliberately pitched above what most men need. The yardstick for a group is the estimated average requirement, and against that 350 mg the average man in his thirties to fifties sits almost exactly on the line, while the average man over 70, at 321 mg, sits below it, as does the average man in his twenties, at 312 mg against an EAR of 330 mg. The Office of Dietary Supplements' 48% figure is that comparison done across the whole distribution of intakes rather than at the average, which is why it is the number to quote.
The 2003–2006 analysis behind the 268 mg figure, by Bailey and colleagues (American Journal of Clinical Nutrition, 2011), found something else worth knowing: supplement users already ate more magnesium. Men who took a magnesium-containing supplement averaged 350 mg a day from food alone, against 268 mg for men who did not. The people adding a capsule are, on average, not the people with the least magnesium on their plates.
Which foods have the most magnesium?
Seeds, nuts, leafy greens, beans and whole grains. By the NIH Office of Dietary Supplements' table, an ounce of roasted pumpkin seeds carries 156 mg, an ounce of chia seeds 111 mg, an ounce of dry-roasted almonds 80 mg, half a cup of boiled spinach 78 mg and half a cup of cooked black beans 60 mg. Those five servings together carry 485 mg, more than the 420 mg RDA. About 30% to 40% of the magnesium in food is absorbed.
| Food | Serving | Magnesium | % DV |
|---|---|---|---|
| Pumpkin seeds, roasted | 1 ounce | 156 mg | 37% |
| Chia seeds | 1 ounce | 111 mg | 26% |
| Almonds, dry roasted | 1 ounce | 80 mg | 19% |
| Spinach, boiled | 1/2 cup | 78 mg | 19% |
| Cashews, dry roasted | 1 ounce | 74 mg | 18% |
| Peanuts, oil roasted | 1/4 cup | 63 mg | 15% |
| Shredded wheat cereal | 2 large biscuits | 61 mg | 15% |
| Black beans, cooked | 1/2 cup | 60 mg | 14% |
| Edamame, shelled, cooked | 1/2 cup | 50 mg | 12% |
| Peanut butter, smooth | 2 tablespoons | 49 mg | 12% |
| Brown rice, cooked | 1/2 cup | 42 mg | 10% |
| Yogurt, plain, low fat | 8 ounces | 42 mg | 10% |
| Banana | 1 medium | 32 mg | 8% |
| Milk | 1 cup | 27 mg | 6% |
| Salmon, Atlantic, farmed, cooked | 3 ounces | 26 mg | 6% |
| Chicken breast, roasted | 3 ounces | 22 mg | 5% |
| Beef, ground, 90% lean | 3 ounces | 20 mg | 5% |
| Broccoli, chopped, cooked | 1/2 cup | 12 mg | 3% |
Every row is the Office of Dietary Supplements' figure, which it draws from the USDA's FoodData Central, and the % DV column is measured against 420 mg. The absorption figure needs one clarification, because it is often used to make the allowance sound unreachable: the RDA is an intake figure that already allows for incomplete absorption. A man does not need to eat three times 420 mg. He needs to eat 420 mg, and the meat and dairy rows show why a diet built on them alone tends to land short of it.
Does a man need more magnesium after 50?
Not by the RDA, which is 420 mg a day from 31 onward and does not change at 51 or at 71. What changes is the body's handling of it: the NIH Office of Dietary Supplements notes that absorption from the gut falls and excretion by the kidneys rises with age, and men aged 71 and older are among the groups it identifies as most likely to have low intakes. The target stays the same while it gets harder to reach.
The USDA table above shows the same drift: average intake from food and drink falls from 357 mg in men aged 50 to 59 to 321 mg after 70. For a man over 45 the practical reading is unglamorous: the number does not move, the diet supplies most of it, and any supplement counts against 350 mg. How to choose one, if the arithmetic says to, is in how to choose a magnesium supplement.
What the research does not show
The allowance is less certain than its round number suggests. The American figures rest on balance studies collated before 1997. When the European Food Safety Authority's panel reviewed magnesium in 2015, it concluded that the data could not support an average requirement at all and set an adequate intake of 350 mg a day for men instead, based on average intakes observed in dietary surveys from nine EU countries. An allowance and an adequate intake are different kinds of number, but two expert bodies looking at overlapping evidence still landed 70 mg apart, and neither figure is a measured threshold for an individual.
The ceiling is contested too: a 2023 perspective argues that the American figure is too cautious. A tolerable upper intake level is a line drawn for a population, not a point at which every person reacts.
And nobody can say from a survey or a label whether a particular man is short. The Office of Dietary Supplements notes that NHANES has not measured serum magnesium in its participants since 1974, that magnesium is not part of routine electrolyte testing, and that less than 1% of the body's magnesium is in serum, held under tight control. Intake figures describe diets, not bodies. What magnesium does in the body is the same whichever source supplies it. Magnesium supports normal muscle function.* The trials behind each claim made for magnesium, and their limits, are collected in the magnesium research summary.
*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.
Where Night Work sits
Night Work is magnesium glycinate in capsules: by its label, 275 mg of elemental magnesium from 2,500 mg of magnesium glycinate per three-capsule serving, 30 servings, 65% of the Daily Value. It is the only supplemental magnesium in the TARE range, so the label's 275 mg is the whole of the range's supplemental total, 75 mg under the 350 mg tolerable upper intake level. That 75 mg is the room a multivitamin or an antacid would take, not a target. What is and is not measured for Night Work is set out on Testing & Certification.
Sources
- NIH Office of Dietary Supplements. Magnesium: Fact Sheet for Health Professionals (updated 6 January 2026). NIH Office of Dietary Supplements
- Institute of Medicine. Dietary Reference Intakes for Calcium, Phosphorus, Magnesium, Vitamin D, and Fluoride. National Academy Press, 1997. nationalacademies.org
- U.S. Department of Agriculture, Agricultural Research Service. Nutrient Intakes from Food and Beverages, by Male/Female and Age, What We Eat in America, NHANES 2017-March 2020 Prepandemic, Table 1 (2022). ars.usda.gov
- Bailey RL, Fulgoni VL, Keast DR, Dwyer JT. Am J Clin Nutr 2011;94(5):1376-1381. PubMed 21955646
- EFSA Panel on Dietetic Products, Nutrition and Allergies. Dietary Reference Values for magnesium. EFSA Journal 2015;13(7):4186. efsa.europa.eu
- Costello R, Rosanoff A, Nielsen F, West C. Adv Nutr 2023;14(5):973-982. PubMed 37487817