Washington, DC—The Council for Responsible Nutrition (CRN) is raising its recommended safe upper level (UL) for magnesium supplements to 500 milligrams per day for healthy adults. The change is based on an updated evaluation that looked at new human clinical data showing that higher levels of the mineral are well tolerated. The UL applies to supplemental magnesium in adults with normal kidney function (those with kidney disease or related conditions should consult with a healthcare provider before using magnesium-containing supplements).The previous supplemental UL was 400 mg/day
The revision is part of CRN’s ongoing release of updated nutrient safety chapters from its flagship reference book, Vitamin and Mineral Safety (4th edition). CRN reported that the new magnesium chapter is the latest installment in a series of updates that are being made available early to provide industry, practitioners, and policymakers with timely access to current science on nutrient safety.
“This updated UL reflects a growing body of evidence that magnesium is well tolerated—even at higher levels than previously recognized,” said Andrea Wong, Ph.D., CRN Senior Vice President, Scientific and Regulatory Affairs. “For formulators of magnesium supplements to support bone, muscle, nerve, or heart health, this offers greater confidence in the safety of levels up to 500 mg/day.”
Magnesium fast facts from CRN consumer data
- Magnesium is one of the top five most used dietary supplements.
- Magnesium is taken by 23% of supplement users (up from about one in five in 2023).
- Magnesium use is especially high among women and older adults
- Magnesium use tends to increase with higher household incomes.
- Approximately 27% of female supplement users take magnesium.
- Approximately 19% of male supplement users take magnesium.
- Consumers aged 55 and older report higher magnesium usage than younger adults.
- Consumers cite a variety of reasons for taking magnesium, including helping with relaxation and sleep.
About CRN’s nutrient safety assessments
The evaluations focus specifically on supplemental intakes, using a rigorous risk assessment approach grounded in human clinical data, CRN shared. More than 60 clinical trials published since 2014 were identified in the update and none of the research showed evidence that large quantities of oral magnesium are associated with serious adverse effects in people with normal kidney function. Gastrointestinal symptoms such as occasional diarrhea were reported inconsistently and were considered “nuisance effects,” not indicators of health risk, according to CRN.
CRN noted that the updated magnesium chapter follows its January 2025 announcement launching early access to updated chapters from Vitamin and Mineral Safety, a foundational resource originally authored by the late Dr. John Hathcock. That release introduced revised chapters on vitamin B6, vitamin E, and zinc, and previewed the methodology now used to evaluate new data for UL determinations. News chapters are being released on a rolling basis, and the complete 4th edition will be published upon finalization of all chapters.
