The Council for Responsible Nutrition (CRN), a trade association for the dietary supplement and functional food industry, has completed an updated evaluation of magnesium safety, raising its recommended safe upper level (UL) for magnesium supplements to 500 mg per day for healthy adults, based on new human clinical data showing that higher levels are well tolerated, raising it from a previous recommended UL of 400 mg per day.

The revision comes as part of CRN’s ongoing release of its updated nutrient safety chapters from its reference book, Vitamin and Mineral Safety (4^th edition). The new chapter, released today, is the latest installment in a series of updates made available early to provide the public with timely access to the current science.

“This updated UL reflects a growing body of evidence that magnesium is well tolerated—even at higher levels than previously recognized,” said Andrea Wong, PhD, senior vice president of consumer 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.”

CRN’s recent survey found that magnesium is one of the top five most-used supplements today, taken by 23% of all supplement users. The same survey found that use is especially high in women and older adults, and it tends to increase with higher household incomes. About 27% of female supplement users take magnesium, compared to 19% of males, and those aged 55 and older report higher usage than younger adults.

CRN’s nutrient safety assessments focus specifically on supplemental intakes, using a rigorous risk assessment approach grounded in human clinical data. Over 60 clinical trials published since 2014 were identified in the update and none 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.

The UL applies to supplemental magnesium in adults with normal kidney function. Individuals with kidney disease or related conditions should consult with a healthcare provider before using magnesium-containing supplements.

The update follows CRN’s January 2025 announcement that it would launch early access to updated chapters from Vitamin and Mineral Safety, a resource originally authored by the late John Hatchcock. That release included updates on vitamins B6 and E, and zinc. It previewed the methodology used to evaluate new data for UL determinations.

All chapters will be released on a rolling basis to provide stakeholders with real-time access to updated safety conclusions. The complete 4^th edition will be published upon finalization of all chapters.