Functional foods may do more than simply supply the macronutrients and micronutrients your body needs for normal biochemical reactions. They contain compounds or ingredients that may help reduce your risk for certain health conditions or promote better health. These compounds can occur naturally in the functional foods or they can be added by fortification or enrichment.
The term "functional foods" doesn't have any legal meaning in the United States, but it's defined by the Institute of Food Technologists as "foods or food components that provide a health benefit beyond basic nutrition." The Food and Drug Administration (FDA) doesn't have a definition for it, but it does regulate what health claims can be made on the labels of foods and beverages.
Health Canada defines functional foods as being "similar in appearance to, or may be, a conventional food, is consumed as part of a usual diet, and is demonstrated to have physiological benefits and/or reduce the risk of chronic disease beyond basic nutritional functions." The European Commission Concerted Action on Functional Food Science in Europe considers foods to be functional if they have a beneficial affect on one or more functions of the body and are still in the form of food, not a dietary supplement.
The Academy of Nutrition and Dietetics (AND) defines functional foods as foods "that include whole foods and fortified, enriched or enhanced foods have a potentially beneficial effect on health when consumed as part of a varied diet on a regular basis, at effective levels." The AND breaks down functional foods into four categories: conventional foods, modified foods, medical foods, and foods for special dietary use.
Conventional Foods: These are the most basic of the functional foods because they haven't been modified by enrichment or fortification; they're still in their natural state. Most whole fruits and vegetables fall into this category because they're rich in phytochemicals such as lycopene and lutein, as well as other beneficial compounds.
Modified Foods: Foods that have been enriched, fortified or enhanced with nutrients or other beneficial ingredients. Calcium-fortified orange juice, folic acid enriched breads and margarine enhanced with plant sterols are functional foods that have been modified. Energy drinks that have been enhanced with herbs such as ginseng and guarana, as well as other potentially controversial foods, also fall into this category.
Medical Foods: The FDA defines medical food as "food which is formulated to be consumed or administered enterally under the supervision of a physician and which is intended for the specific dietary management of a disease or condition for which distinctive nutritional requirements, based on recognized scientific principles, are established by medical evaluation." Medical foods include specialized formulas designed for people who have specific health problems. These foods require the help and supervision of a health care provider.
Foods for Special Dietary Use: These are similar to medical foods, but they're available commercially and don't require the supervision of a health care provider. These foods fill special dietary needs that are due to specific health conditions, such as celiac disease, lactose intolerance, or obesity. Gluten-free foods, lactose-free dairy products and foods designed to aid weight loss are considered foods for special dietary use if you have those conditions. Infant foods are also in this category.
Health Claims: The FDA allows certain health claims to be placed on food labels. Nutrient content claims, structure and function claims, or health claims can be placed on labels. Nutrient content claims describe the content of the foods and can include words like "free," "low," and "reduced." Calorie-free foods, low-fat foods and reduced-sodium foods display these types of claims. Structure and function claims describe the role of a nutrient in the function of your body. A yogurt label, for example, can claim "calcium builds strong bones." Health claims must be approved by the FDA. For example, foods that contain olive oil or oats and oatmeal can make specific claims about how those ingredients affect health.
Hasler CM, Brown AC; Academy of Nutrition and Dietetics. "Position of the Academy of Nutrition and Dietetics: functional foods." J Am Diet Assoc. 2009 Apr;109(4):735-46.
U.S. Food and Drug Administration. "Claims That Can Be Made for Conventional Foods and Dietary Supplements." Accessed August 16, 2011. http://www.fda.gov/Food/LabelingNutrition/LabelClaims/ucm111447.htm