Attività

That foods might provide therapeutic benefits is clearly not a new concept. The tenet, “Let food be thy medicine and medicine be thy food” was embraced 2500 years ago by Hippocrates, the father of medicine. However, this “food as medicine” philosophy fell into relative obscurity in the 19th century with the advent of modern drug therapy. In the 1900s, the important role of diet in disease prevention and health promotion came to the forefront once again.

During the first 50 years of the 20th century, scientific focus was on the identification of essential elements, particularly vitamins, and their role in the prevention of various dietary deficiency diseases. This emphasis on nutrient deficiencies or “undernutrition” shifted dramatically, however, during the 1970s when diseases linked to excess and “overnutrition” became a major public health concern. Thus began a flurry of public health guidelines, including the Senate Select (McGovern) Committee's Dietary Goals for the United States (1977), the Dietary Guidelines for Americans (1980, 1985, 1990, 1996, 2000— a joint publication of the USDA and the Department of Health and Human Services), the Surgeon General's Report on Nutrition and Health (1988), the National Research Council's Diet and Health (1989) and Healthy People 2000 and 2010 from the U.S. Public Health Service. All of these reports are aimed at public policy and education emphasizing the importance of consuming a diet that is low in saturated fat, and high in vegetables, fruits, whole grains and legumes to reduce the risk of chronic diseases such as heart disease, cancer, osteoporosis, diabetes and stroke.

Scientists also began to identify physiologically active components in foods from both plants and animals (known as phytochemicals and zoochemicals, respectively) that potentially could reduce risk for a variety of chronic diseases. These events, coupled with an aging, health-conscious population, changes in food regulations, numerous technological advances and a marketplace ripe for the introduction of health-promoting products, coalesced in the 1990s to create the trend we now know as “functional foods.” This report includes a discussion of how functional foods are currently defined, the strength of the evidence both required and thus far provided for many of these products, safety considerations in using some of these products, factors driving the functional foods phenomenon, and finally, what the future may hold for this new food category.

The International Life Sciences Institute defines them as “foods that, by virtue of the presence of physiologically-active components, provide a health benefit beyond basic nutrition” (3). In a 1999 position paper, the American Dietetic Association defined functional foods as foods that are “whole, fortified, enriched, or enhanced,” but more importantly, states that such foods must be consumed as “… part of a varied diet on a regular basis, at effective levels ” for consumers to reap their potential health benefits (4).

Another term often used interchangeably with functional foods, although it is less favored by consumers, is “nutraceuticals,” a term coined in 1991 by the Foundation for Innovation in Medicine to refer to nearly any bioactive component that delivers a health benefit. In a 1999 policy paper, Zeisel (5) astutely distinguished whole foods from the isolated components derived from them in his following definition of nutraceuticals: “those diet supplements that deliver a concentrated form of a presumed bioactive agent from a food, presented in a nonfood matrix, and used to enhance health in dosages that exceed those that could be obtained from normal food.”

Several factors are responsible for the fact that this is one of the most active areas of research in the nutrition sciences today: 1) an emphasis in nutritional and medical research on associations between diet and dietary constituents and health benefits, 2) a favorable regulatory environment, 3) the consumer self-care phenomenon, and 4) rapid growth in the market for health and wellness products.

Criteria for sound science

According to the Department of Health and Human Services, diet plays a role in 5 of 10 of the leading causes of death, including coronary heart disease (CHD), certain types of cancer, stroke, diabetes (noninsulin dependent or type 2) and atherosclerosis. The dietary pattern that has been linked with these major causes of death in the United States and other developed countries is characterized as relatively high in total and saturated fat, cholesterol, sodium and refined sugars and relatively low in unsaturated fat, grains, legumes, fruits and vegetables. An accumulating body of research now suggests that consumption of certain foods or their associated physiologically active components may be linked to disease risk reduction (6). The great majority of these components derive from plants; however, there are several classes of physiologically active functional food ingredients of animal or microbial origin.