chapter  10
Bioavailability Issues of Nonnutrient Plant and Fruit Constituents
Pages 14

The basic function of food is to provide compounds necessary for maintaining physiological functions of the organism including energy and building material. The results of epidemiological studies point out that consumption of plant food is benecial to human health and this effect is in substantial part attributed to an array of plant constituents classied as nonnutrients, that is, not associated with basic food functions. The available data show that though not yet fully recognized mechanisms, they may prevent the development of several diseases including cardiovascular ones and some cancers. This preventive action is attributed to a number of phytochemicals, very often secondary metabolites, present in food at low concentrations. Among many nonnutrient constituents of plant food polyphenols (tannins, ¤avonoids, iso¤avones, and phenolic acids), glucosinolates, lycopene, resveratrol, phytins, dietary ber, and many other have become the compounds of interest in a number of studies aimed at explaining their positive effect. The results obtained thus far lead to the conclusion that benecial physiological effect on humans is rather a result of a concerted action of different, from chemical point of view, groups of compounds than of a single compound isolated from a complex food matrix. Recent attention paid to the power of food which is no more regarded only as a source of nutrients and energy but also as a source of a large number of compounds with a potent biological activity has changed

10.1 Introduction .................................................................................................. 173 10.2 Bioavailability Basics ................................................................................... 174 10.3 Double Face of Plant and Fruit Nonnutrients ............................................... 176 10.4 Gastrointestinal Tract and Plant and Fruit Nonnutrients .............................. 177

10.4.1 Oral Cavity ....................................................................................... 178 10.4.2 Stomach ............................................................................................ 178 10.4.3 Small Intestine .................................................................................. 179 10.4.4 Colon ................................................................................................. 181

10.5 Metabolism Distribution and Elimination of Nonnutrient Components ..........181 References .............................................................................................................. 182

the general attitude toward food. Only recently have typical nutritional experiments received the support by techniques thus far reserved exclusively for pharmacology. To study how food may affect the consumer organism, pharmacological approach with all its tools is applied. Quantication of food components which may interact with the consumer organism at the systemic level is a prerequisite to study in vivo effects of nonnutrients beyond the gastrointestinal tract. From the nutritional point of view, nonnutrient plant and fruit constituents are xenobiotics, and once ingested, they are ef- ciently metabolized and eliminated from the organism; usually, it is not the parent compounds but their metabolites that are present in the systemic circulation.