Some doctors say they have recommended that their patients stop taking multivitamins. Others say the evidence that vitamins lack benefits or cause harm isn't well established.
"My overall impression is these studies change nothing, and leaves some puzzles and questions for future study," said Dr. Michael Roizen, chief wellness officer of the Cleveland Clinic. "I'm still taking [supplements because the data supports] a multi without iron, and with low dose of vitamin A and E, 1,200 IU of vitamin D3 a day; DHA (900 mg); Lutein (20 mg), a probiotic, a little extra calcium [with magnesium], and my two baby aspirins with plenty of water."
Many experts say most Americans eat well enough to get the vitamins and nutrients they need without taking supplements.
Dr. Alice Lichtenstein, a director and senior scientist at the Cardiovascular Nutrition Laboratory at Tufts University, said the ones who are most likely to take supplements usually see the least amount of benefit from them.
"A multi-vitamin supplement will only be beneficial if the person taking it habitually consumes a diet deficient in one or more of the nutrients contained in the supplement," she said. "Since the majority of Americans do not habitually consume nutrient-deficient diets, especially those individuals most likely to take a multi-vitamin supplement, it is not surprising that no benefit would be garnered."
Dr. Jana Klauer, a private practice nutrition physician, said the surest way to get a healthy amount of nutrients is on your plate.
"My advice? Don't waste your money on a multiple vitamin," she said. "Buy fresh vegetables and fruits. Vitamins contained within these have health benefits."