Nutraceutical, type of food substance that helps to maintain health and prevent illness. Nutraceutical is sometimes used interchangeably with the terms functional food and dietary supplement, though there are distinctions.

Functional foods are foods normally consumed in the diet that have scientifically assessed health benefits. Dietary supplements are ingestible preparations purposefully added to the diet to benefit health but are not necessarily derived from foods. Nutraceuticals, on the other hand, are products with biological functions that are derived only from foods. Similar to dietary supplements, they generally are consumed in a form that resembles a medicinal product, and they usually are sold over-the-counter (OTC).