A recommended dietary allowance
But what about taking a daily vitamin supplement? This kind of practice should not be harmful. But does it do any good? Medical research does not seem to find any benefit in taking daily vitamin supplements. According to the federal government’s 2015–2020 Dietary Guidelines for Americans, “nutritional needs should be met primarily from foods. Foods in nutrient-dense forms contain essential vitamins and minerals and also dietary fiber and other naturally occurring substances that may have positive health effects. In some cases, fortified foods and dietary supplements may be useful in providing one or more nutrients that otherwise may be consumed in less-than-recommended amounts.” But taking recommended doses doesn’t seem to do any harm either.
Nutrients of special public health concern in U.S. diets are calcium, potassium, dietary fiber, and vitamin D in both adults and children. Some people need nutritional supplements to treat medical conditions, such as women who take iron supplements during pregnancy or a person who takes supplements of a specific vitamin because of a diagnosed deficiency. So, what should a reasonable person do? How would you choose whether you need a daily dose of a multivitamin? And how much?