The concept of functional foods first became popular in Japan in the 1980s. The Japanese government developed a regulatory agency to oversee the approval of functional foods in 1991. The name of this agency is called Foods for Specified Health Use (FOSHU).

Functional foods are increasingly popular in the United States. A significant number of popular, mainstream brand name products are available on the market. The Nutrition Action Healthletter notes that an increasing number of major brands are planning or developing labels that purport the benefits of eating their functional foods. Furthermore, functional foods are reported as one of the fastest growing segments of the food economy in United States. In the past decade, functional foods have become so popular that other governments, including Japan, Canada, and the United Kingdom have devoted major health initiatives to investigating the usefulness and safety of functional foods.

Some foods are said to be inherently functional foods, such as green tea, which has antioxidants, and salmon, which contains omega 3 fatty acids.

Functional foods are also often created when foods are processed. Foods may be fortified to include more fiber or calcium, for example. Consumers are advised to choose foods that appear healthy according to the way they fit into their food pyramid, rather than on the claims of additional, and usually unproven, beneficial properties.

Nutrition bars contain herbs, supplements, vitamin, minerals and or/protein. There are many different forms including protein bars, meal replacement bars, energy bars and diets bars.

In addition to nutrition bars, fermented foods are also included in the functional food category. A common example is yogurt, which often contains live bacterial cultures known as probiotics. These fermented foods are thought to promote a healthy environment in the body.