How can the Recommended Daily Allowance (RDA) for magnesium be higher than the Upper Tolerable Intake Level (UL)? That is, how can an amount which is healthful also put you at risk for harm?
It is true that, at first glance, there seems to be a contradiction. For example, the UL for magnesium (above which the risk of adverse effects increases) is 350 mg per day for adults and children over age 8, but the RDA (the amount one needs) can be as high as 420 mg for many people within this group depending on gender and stage of life. However, the magnesium one consumes from food does not count toward the UL
; only magnesium from supplements and medicine can cause adverse effects and counts toward this limit. So, as long as you're not getting more than 350 mg of magnesium per day from supplements and/or medicine and are getting some magnesium from foods (like whole grains, nuts, beans, and green leafy vegetables) you can satisfy the RDA without exceeding the UL.
For more about this, see the "What to Consider When Using" section of the Magnesium Supplements Review
The ULs established for niacin
also only apply to the amounts consumed from supplements and fortified foods and not from foods naturally containing these vitamins. For vitamin E
, the upper limit is higher for the natural form than the synthetic form.
For recommended daily intakes and upper limits for these and other nutrients, based on gender and stage of life, see ConsumerLab.com's Recommended Daily Intakes and Upper Limits
Learn more about magnesium:
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Is it true that I should not keep magnesium supplements in a daily pill pack mixed with other supplements and medicines? >>
Help! How do I know how much magnesium I am actually getting from my supplement? The label says it contains 500 mg of magnesium "as magnesium citrate" -- but how much of that is magnesium and how much is citrate? >>
Is there an accurate test for magnesium deficiency? >>
Are there drug interactions with magnesium supplements? >>
Do any supplements help for restless legs syndrome? >>
I've read that magnesium deficiency is rare but also that most people don't get enough magnesium. How can these both be true? >>
Do magnesium creams, sprays and oils really work? >>
This CL Answer initially posted on 7/14/2015.
Last updated 8/3/2017.