From 2011 to 2020, the percentage of Americans who reported taking a hair, skin and nail vitamin in the past month rose from 2.5% to 4.9%. "Someone died because a heart attack was missed [during testing]," Friedman explains, saying that the patient's troponin levels weren't showing any sign for concern. "They weren't elevated in this one individual who was taking a biotin supplement for hair growth." Biotin, or vitamin B7, is commonly found in most foods and multivitamins, so people rarely need supplements, anyway, says Friedman. "If you were biotin deficient, you wouldn't be going to Walgreens to buy a bottle of biotin," he says.

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Persons: Dr, Rebecca Hartman, Hartman, Adam Friedman, Friedman Organizations: American Academy of Dermatology, Harvard Medical School, CNBC, U.S . Food, Drug Administration, George Washington University, Walgreens Locations: U.S