A dietary supplement is any product that contains a "dietary ingredient" intended to add to the diet. These ingredients may be any of the following substances:
- a vitamin,
- a mineral,
- an herb or other botanical,
- an amino acid, or
- a substance such as an enzyme.
FDA considers dietary supplements to be foods instead of drugs. Each must be labeled as a dietary supplement and have a "Supplement Facts" label. Doctors may prescribe prenatal vitamins and mineral supplements. When a supplement is ordered by prescription it is regulated as a drug, not a food.