This varies from person to person. Higher risk groups may need to supplement earlier than others. For example, adolescents with heavy menstrual bleeding, young vegans or vegetarians, or children with deficiencies or malabsorption issues may benefit from taking supplements from a younger age. For healthy individuals that eat an adequate and varied diet, vitamin supplementation may never be necessary. As always, work with your healthcare provider to determine if and when supplementation is right for you.