At what age should a person switch from children's to adult's vitamins?

Never: A number of recent studies have raised serious questions about taking multi-vitamins. You or your child should not be taking synthetic vitamins, or any supplements for that matter unless advised by a doctor for a known deficiency. You and your child are better off with a full diet of fruits, vegetables, beans, nuts, whole grains, and wild salmon. Spend your money on real foods not hype.