CRN's updated evaluation raises safe intake level for magnesium supplements
The Council for Responsible Nutrition has completed an updated evaluation of magnesium safety, raising its recommended safe upper level for supplements to 500 milligrams per day for healthy adults, based on new human clinical data that the organization said shows that higher levels are well tolerated.
The revised supplemental UL—up from the previous 400 mg/day—comes as part of CRN’s ongoing release of updated nutrient safety chapters from its flagship reference book, Vitamin and Mineral Safety (4th edition). The new magnesium chapter is the latest installment in a series of updates 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, CRN’s 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.”
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Magnesium is one of the top five most used dietary supplements, taken by nearly one in four supplement users (23%) – up from about one in five in 2023, based on CRN survey data. The same survey found magnesium use is especially high among 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. Consumers cite a variety of reasons for taking magnesium, including helping with relaxation and for better sleep. Overall, these findings highlight magnesium’s growing appeal as a go-to supplement for broad health and wellness benefits, CRN said.
CRN’s nutrient safety assessments focus specifically on supplemental intakes, using a rigorous risk assessment approach grounded in human clinical data. More than 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, CRN said. Gastrointestinal symptoms such as occasional diarrhea were reported inconsistently and were considered “nuisance effects,” not indicators of health risk, CRN said.
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, CRN noted.
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The updated magnesium chapter follows CRN’s 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.
All chapters are being released on a rolling basis to provide stakeholders with real-time access to updated safety conclusions. The complete 4th edition will be published upon finalization of all chapters.
To view the updated magnesium chapter and learn more about this resource, visit https://www.crnusa.org/resources/vitamin-mineral-safety.