Functional effects of food components and the gastrointestinal system: chicory fructooligosaccharides.

Functional food science, as recently proposed by ILSI Europe, opens new perspectives in nutrition and food sciences. The systematic investigation of the interactions between food components or food ingredients and genomic, biochemical, cellular, or physiological functions is a unique way to improve both our knowledge and the role of nutrition in maintaining good health and in preventing disease. However, such basic knowledge is insufficient to justify claims, unless it is confirmed through relevant nutrition studies aimed at demonstrating the same effect and its positive consequences in humans. In the first stage, this demonstration will in most cases justify functional (physiological) claims (e.g., bifidogenic effect for fructooligosaccharides, bulking effect for nondigestible carbohydrates, protection against oxidative stress for antioxidants) with no reference to any health benefit. A true health claim will require, in most cases, additional studies involving large populations and long-term trials. It is anticipated that the better we understand the mechanism of interactions between food components and specific biological functions, the more we will be able to demonstrate functional effects, and the easier it will be to accumulate convincing evidence in favor of health promotion or disease prevention. Because of both its direct contact with eaten foods and the diversity of its functions, the GI system is a potential target for many functional effects. Until now, only a limited number of these effects have been investigated so as to justify functional claims. Improvement of glucose absorption (leading to physiological glycemia and insulinemia), modulation of GI transit time, fecal bulking, acidification of colonic content, and control of cholesterol bioavailability are all recognized effects of dietary fiber. Balanced colonic microflora and immunostimulation are attributed to the consumption of probiotics. Prebiotics selectively modify the colonic microbiota and modulate hepatic lipogenesis. According to the ILSI Europe strategy for the development of functional foods, all these effects are of interest. Their support by sound scientific arguments will be a necessary condition for their implementation in food science and nutrition for the benefit of human health.