Functional foods are those products (foods or beverages) that provide added health benefits beyond their basic nutritional value. These health benefits may involve lowering the risk of certain diseases or conditions, or strengthening a person’s health in particular areas. Functional foods are also sometimes known as nutraceuticals, medicinal foods or designer foods.

Most, if not all, whole foods contain substances that appear to provide some type of health benefit beyond nutrition alone. For example, many different fruits and vegetables, nuts, oils, tea and wine include components that act as antioxidants (substances that neutralize cellular damage in the body), which may help reduce the risk of cancer.

In addition, whole foods may be altered or enhanced in order to provide specific health benefits. For example, low-fat foods can help reduce the risk of cardiovascular disease, and orange juice with added calcium may help strengthen bones.

Food is typically consumed for its taste and nutritional value. The types of nutrients provided by food are carbohydrates, fats, proteins, water, as well as certain vitamins and minerals. Nutrients are the chemical substances that help build, repair and maintain tissue growth throughout the body. Some nutrients are also transformed into energy in the body, which allows for the movement and proper functioning of various body processes. Other nutrients act as catalysts in the many reactions that occur in the body, including making energy.

To be considered functional, food must include a component associated with a specific health benefit in addition to its basic nutrients. Such components may naturally occur in the food, may be added to the food, or may be used to produce the food. They are sometimes referred to as bioactive food components because of their active effect on the body.

Some components come from animal sources and are sometimes referred to as zoochemicals. Many come from plant sources and are known as phytochemicals. There are thousands of phytochemicals, some of which may be associated with a variety of health benefits when consumed.

The bioactive food components in functional foods may perform different actions within the body, which can result in specific types of health benefits. These potential actions include:

• Antioxidant activity. Substances neutralize the cellular damage done by free radicals, the toxic chemical compound produced when oxygen is metabolized by the body. This slows the wear of body cells, and may lower the risk of heart disease and inhibit growth of cancer cells. Many different substances act as antioxidants. This includes phytochemicals (e.g., carotenoids, flavonoids, resveratrol, ellagic acid), vitamins (e.g., vitamins A, C and E) and minerals (e.g., selenium).
  
  
• Hormonal action. Certain phytochemicals called phytoestrogens may mimic or alter the hormone estrogen in the body. This may provide consumers the possible benefits of estrogen (e.g., lowered cholesterol levels, strong bones, healthy heart, relief from hot flashes associated with menopause) while reducing the risk of reproductive cancers associated with estrogen (e.g., breast cancer, ovarian cancer). Phytochemicals that may act in this way include daidzein, genistein and lignans.
  

  

• Stimulation of enzymes. Certain phytochemicals can trigger enzymes to act in such a way that reduces the risk of disease (e.g., cancer). Stimulated enzymes may neutralize and/or remove carcinogens from the body. The class of phytochemicals known as isothiocyanates may perform this action.
  
  
• Interference with DNA replication. Certain substances can interfere with the replication of cells, which may inhibit growth of cancer cells. Phytochemicals such as saponins may act in this way.
  
  
• Antibacterial effect. Certain substances in functional foods can inhibit the growth of particular types of bacteria in the body. This includes probiotics (e.g., lactobacilli in certain yogurts that help manage levels of helpful and harmful bacteria in the digestive tract) and the phytochemical allicin (found in garlic).

In the United States, functional foods are an emerging trend not yet legally defined and facing limited regulation. In 1994, the National Academy of Science’s Food and Nutrition Board provided what has become the most commonly accepted definition of functional foods today -- foods that provide health benefits in addition to their basic nutrients.  

While oversight in the area of functional foods is still developing, the concept of functional foods is not new. In the 1920s, the mineral iodine was added to table salt in an effort to reduce the risk of goiter (an enlarged thyroid gland), which may occur due to a lack of iodine in the diet. Iodized salt is an early example of a food product enhanced to provide a specific health benefit beyond its nutritional value.  

Functional foods differ from health food, a generic term that is often used to refer to whole foods that are organically grown (produced without exposure to pesticides or chemical additives).

Functional foods differ from dietary supplements primarily in their intended use. Functional foods are conventional foods generally consumed for their taste as well as nutritional value. Dietary supplements are nutrients supplied in pill or liquid form that are intended to add to the food consumed as a part of a person’s diet.