 Do you use a multivitamin every day? They may not be doing as much good as you hoped. Deborah Rodriguez explains. Researchers at the National Institutes of Health studied more than 400,000 healthy Americans over the age of 20. They found taking daily multivitamins did not help them live longer. Medical contributor Dr. Celine Gounder. What we're seeing is whether it's death from cancer, from heart disease, from stroke, we're not seeing a benefit. Dr. Gounder says there are exceptions.