Changes in diet and/or consumption of a magnesium dietary supplement can help people achieve the recommended intakes and support good health. Government agencies have also identified an upper limit that should not be exceeded. Supplement use below this limit is considered safe, although there are a few clearly identified conditions for which additional restriction of magnesium intake may be warranted. The NIH Office of Dietary Supplements (ODS) has a Fact Sheet for Health Professionals at: https://ods.od.nih.gov/factsheets/Magnesium-HealthProfessional/ It includes a list of magnesium-rich foods.
KEY POINTS
| RDA for women ages 31 and older | 320 mg/day |
| RDA for men ages 31 and older | 420 mg/day |
- Fewer than 10% of adults consume the RDA from food and beverages
- A supplement containing less than 350 mg is safe (Europe sets cut-off at 250 mg).
The Food and Nutrition Board of the U.S. Institute of Medicine updated Estimated Average Requirements (EARs) and Recommended Dietary Allowances (RDAs) for magnesium in 1997.2 As for safety, the Food and Nutrition Board also sets Tolerable Upper Intake Levels (known as ULs) for vitamins and minerals when evidence is sufficient. Collectively the EARs, RDAs and ULs are referred to as Dietary Reference Intakes (DRIs).
The current EARs for magnesium for women and men ages 31 and up are 265 mg/day and 350 mg/day, respectively. The RDAs are 320 and 420 mg/day. RDAs are higher than EARs so as to identify amounts that will cover people with higher than average requirements. RDA for pregnancy is 350 to 400 mg/day depending on age of the woman. RDA for lactation ranges 310 to 360 mg/day for same reason.2
In the case of magnesium the UL is set at 350 mg/day.2 The European Food Safety Authority reviewed the same safety question and set its UL at 250 mg/day.3 The magnesium UL is unique in that it is lower than some of the RDAs. It applies to intake from a pharmacological agent or dietary supplement only, the reason being that the more magnesium consumed at one time the less absorbed, and the less absorbed the more reaches the large intestine and causes diarrhea.1,2 The diarrhea adverse effect is not expected for supplements providing less than the UL, but risk can be further reduced by taking a supplement with or after a meal, as this slows movement from the stomach to the small intestine. The UL does not include intake from food and water.
For U.S. food and dietary supplement labeling purposes the amount in a serving is expressed as a percent of Daily Value (DV). For magnesium labeling purposes 100% of the Daily Value is 420 mg. Foods and supplements with a magnesium content are required to show milligrams and DV% in the Facts panel. The amount refers to the magnesium content of the compound(s) in the product. Example: magnesium bisglycinate is 14% magnesium.
TABLE S-3 – Criteria and Dietary Reference Intake Values for Magnesium by Life Stage Group
| EAR (mg/day)a | RDA (mg/day)b | AI (mg/day)c | |||||
| Life Stage | Criterion | M | F | M | F | M | F |
| 0–6 months | Human milk content | – | – | – | – | 30 | 30 |
| 7–12 months | Human milk + solid food | – | – | – | – | 75 | 75 |
| 1–3 years | Extrapolation of balance from older children | 65 | 65 | 80 | 80 | – | – |
| 4–8 years | Extrapolation of balance from older children | 110 | 110 | 130 | 130 | – | – |
| 9–13 years | Balance studies | 200 | 200 | 240 | 240 | – | – |
| 14–18 years | Balance studies | 340 | 300 | 410 | 360 | – | – |
| 19–30 years | Balance studies | 330 | 255 | 400 | 310 | – | – |
| 31–50 years | Balance studies | 350 | 265 | 420 | 320 | – | – |
| 51–70 years | Balance studies | 350 | 265 | 420 | 320 | – | – |
| > 70 years | Intracellular studies; decreases in absorption | 350 | 265 | 420 | 320 | – | – |
| Pregnancy | |||||||
| ≤ 18 years | Gain in lean mass | – | 335 | – | 400 | – | – |
| 19–30 years | Gain in lean mass | – | 290 | – | 350 | – | – |
| 31–50 years | Gain in lean mass | – | 300 | – | 360 | – | – |
| Lactation | |||||||
| ≤ 18 years | Balance studies | – | 300 | – | 360 | – | – |
| 19–30 years | Balance studies | – | 255 | – | 310 | – | – |
| 31–50 years | Balance studies | – | 265 | – | 320 | – | – |
a EAR = Estimated Average Requirement. The intake that meets the estimated nutrient needs of 50% of the individuals in a group.
b RDA = Recommended Dietary Allowance. The intake that meets the nutrient need of almost all(97-98%) individuals in a group.
c Adequate Intake. For healthy infants fed human milk, AI is the estimated mean intake.
From: Summary
Dietary Reference Intakes for Calcium, Phosphorus Magnesium, Vitamin D, and Fluoride.
Institute of Medicine (US) Standing Committee on the Scientic Evaluation of Dietary Reference Intakes.
Washington (DC): National Academies Press (US); 1997
The DRI Magnesium chapter as a free 59-page PDF document2 is available at: https://www.nap.edu/read/5776/chapter/8
