Dietary supplement

A dietary supplement is a manufactured product meant to add to a person's diet, sold as pills, capsules, tablets, powders, or liquids. These products can supply nutrients that come from food or are made synthetically, such as vitamins, minerals, fiber, fatty acids, and amino acids. They may also contain substances not proven essential for life, like plant pigments or polyphenols, which are not technically nutrients but can still be marketed for potential health benefits. Ingredients can come from animals too—for instance, collagen sourced from chickens or fish. Supplements are available in various doses, from single-use to full courses, and can be enhanced with additional nutrients.

In the United States, the supplement industry was valued at $151.9 billion in 2021, with over 95,000 products on the market. About 60% of American adults take dietary supplements, rising to 74% among those over 60, and multivitamins are the most common type. The National Institutes of Health notes that some supplements may help provide essential nutrients or support health and performance for people with limited diets.

U.S. federal regulations prohibit supplement makers from claiming their products prevent or treat diseases. However, companies can use "Structure/Function" wording—like "helps maintain healthy joints"—if there is scientific evidence to back it. Such labels must include a disclaimer that the FDA has not evaluated the claim and that the product is not intended to diagnose, treat, cure, or prevent any disease, as only medications can legally make those claims. The FDA enforces these rules and can ban dangerous supplements or those not made according to good manufacturing practices. In the European Union, the European Commission has set harmonized rules to ensure food supplements are safe and properly labeled.

Under U.S. law, the Dietary Supplement Health and Education Act of 1994 defines a dietary supplement as a product intended to supplement the diet, containing one or more of these ingredients: a vitamin, mineral, herb or other botanical, amino acid, or a dietary substance used to increase total dietary intake, or a concentrate, metabolite, constituent, extract, or combination of these. It must be labeled as a dietary supplement, meant for ingestion, and not represented as conventional food or a sole meal item. It cannot be approved as a new drug, antibiotic, or biologic unless it was marketed as food or a supplement before such approval. DSHEA treats supplements as food, except for drug definition purposes.

Supplements are taken orally and are defined mainly by what they are not: conventional foods, medical foods, preservatives, or drugs. Products like nasal sprays or topical lotions do not qualify. FDA-approved drugs cannot be supplement ingredients. Supplements contain vitamins, essential minerals, amino acids, essential fatty acids, non-nutrient substances from plants, animals, fungi, or bacteria, and, for probiotics, live microorganisms. Ingredients may also be synthetic copies of natural substances, like melatonin. All such products must be labeled as dietary supplements in the U.S. Unlike drugs, no government approval is needed to make or sell them; the manufacturer confirms safety. The FDA only steps in to remove a product if it is deemed unsafe, rather than requiring a risk-benefit analysis before sale.

Types include vitamins, which are organic compounds needed in small amounts that an organism cannot synthesize sufficiently and must get from diet. The term depends on the organism and circumstances. For example, vitamin C is essential for humans, guinea pigs, and bats, but not most other mammals. Vitamin D is not essential for people with enough sun or UV exposure, as the skin synthesizes it. Humans need thirteen vitamins in their diet, most of which are groups of related molecules called vitamers—for instance, vitamin E includes tocopherols and tocotrienols, and vitamin K includes K1 and K2. These are vitamins A, C, D, E, K, thiamine (B1), riboflavin (B2), niacin (B3), and others.