Updated on 9/8/2014
Yes, I do think that children should take vitamins, mostly because so many kids don't eat enough fruits and vegetables and because so often, their diets are full of processed and refined foods. However, vitamin supplements shouldn't be substitutes for whole foods, especially fruits and vegetables.
Start early to teach your children to enjoy healthy food by involving them in its preparation. In my book, "The Healthy Kitchen," Rosie Daley and I give a number of ideas for recipes and snacks that kids will like. Also, try to discourage your children from eating too much fast food, processed food, sugar and caffeine (in cola and other soft drinks). There's no harm in the occasional ice cream, pizza or candy bar in the context of a well-balanced diet, but try to encourage snacking on healthier foods - fresh or dried fruit, a small handful of raw, unsalted nuts such as cashews and walnuts, a piece of flavorful, natural cheese or a piece of dark chocolate.
As far as supplements are concerned, I recommend giving children a complete antioxidant formula as well as multiminerals. One good choice is the pediatric formula of InVite For Kids Multivitamin & Mineral Formula made by Mariposa Botanicals.
My colleague Russell Greenfield, M.D., co-author of "Healthy Child, Whole Child," recommends waiting until children are at least four years old before giving them vitamin or mineral supplements. He reminds me that it isn't always easy to find a good child's multivitamin that isn't made with sugar OR artificial colorings. Russ cautions that children between the ages of four and 12 should get no more than 50% of the adult RDA of the major vitamins and minerals, especially the fat-soluble ones (A,D,E, and K), from supplements. After age 12, kids can safely take the adult dosage.
Be sure to keep the vitamins out of the reach of young children - because some supplements for kids taste and look like candy, there is a danger of overdosing, especially when supplements contain iron.
Andrew Weil, M.D.