According to Reuters experts are questioning why Americans take so many vitamin supplements. Maggie Fox reports:
"Half of American adults are taking multivitamins and minerals and the bottom line is that we don't know for sure that they're benefiting from them," said Dr. J. Michael McGinnis, a senior scholar with the Institute of Medicine, who chaired the panel.
"In fact, we're concerned that some people may be getting too much of certain nutrients," added McGinnis, whose organization advises the federal government on health issues.
The 13-member panel included experts in nutrition, biostatistics, biochemistry, toxicology, geriatric medicine, family medicine, pediatrics, cancer prevention, consumer protection and other fields.
They said much more study was needed on what vitamins Americans lacked in their diets and whether taking supplements provided actual benefit.
Many people may assume that because vitamins and minerals are vital for health, that more is better. But some are toxic at high levels, including vitamin A and iron, and others are simply excreted in the urine.