Supplement shelves can give the impression that almost everyone needs something. Yet for generally healthy adults, a review of 84 studies found that routine vitamin and mineral supplements offered little or no protection against cardiovascular disease, cancer or early death.
Taking a supplement without a clear reason may also cause harm. High doses of some water-soluble vitamins can cause harm, and too much vitamin B6, for example, has been linked to nerve damage. Some fat-soluble vitamins, particularly vitamin A, can accumulate and cause toxicity when taken in excess.
