What is the health risk of too much selenium?
There is a moderate to high health risk of too much selenium. High blood levels of selenium can result in a condition called selenosis . Symptoms include gastrointestinal upsets, hair loss, white blotchy nails, and mild nerve damage. Selenium toxicity is rare in the United States and the few reported cases have been associated with industrial accidents and a manufacturing error that led to an excessively high dose of selenium in a supplement.
The Institute of Medicine has set a tolerable upper intake level for selenium at 400 micrograms per day for adults to prevent the risk of developing selenosis. "Tolerable upper intake levels represent the maximum intake of a nutrient that is likely to pose no risk of adverse health effects in almost al individuals in the general population".
This Fact Sheet was developed by the Clinical Nutrition Service, Warren Grant Magnuson Clinical Center, National Institutes of Health (NIH), Bethesda, MD, in conjunction with the Office of Dietary Supplements (ODS) in the Office of the Director of NIH. The mission of ODS is to strengthen knowledge and understanding of dietary supplements by evaluating scientific information, stimulating and supporting research, disseminating research results, and educating the public to foster an enhanced quality of life and health for the US population.
The Clinical Nutrition Service and the ODS would like to thank the expert scientific reviewers for their role in ensuring the scientific accuracy of the information discussed in this Fact Sheet.