NEW YORK (Reuters Health) - Vitamin supplements are meant to fill-in where diet may be lacking, but a new study finds that U.S. kids may not be getting some of the most needed nutrients from their vitamin pills and the kids taking vitamins may not be the ones who need them the most. Looking at the diets and supplement use of more than 7,000 kids, researchers found that between the ages of nine and 18 many had low levels of certain vitamins and minerals, and few took supplements, while younger kids had adequate levels of most nutrients and were possibly getting too much of some vitamins and minerals. Most children under eight, for instance, got the nutrition they needed from the food they ate, regardless of whether or not they took supplements, the study found. Even with the use of supplements, however, more than a third of children failed to get sufficient calcium and vitamin D. And users sometimes overloaded on essential nutrients such as iron and vitamin A. Zinc and folate were consu...