ISHS Acta Horticulturae 744: I International Symposium on Human Health Effects of Fruits and Vegetables
FLAVONOIDS IN FOOD AND WINE |
| Authors: | M.-J. Amiot-Carlin, F. Tourniaire, A. Margotat |
| Keywords: | polyphenols, antioxidants, cardiovascular diseases, cancers, bioavailability |
| Abstract:
Epidemiological studies, clinical trials and experiments on animals as well as in vitro studies attribute a protective role to flavonoids against degenerative diseases. Flavonoids constitute the largest class of polyphenols, widely spread in the plant kingdom and common in human diet. The main structures are anthocyanins, flavones, flavonols, isoflavones, flavanones and flavanols. Most of flavonoids present in fruits and vegetables are attached to sugars except for flavanols that occur as monomers and as polymers named procyanidins. On the basis of reported studies, different mechanisms may contribute to the biological effects of flavonoids: their antioxidant effects (as reducing agents, singlet oxygen quenchers and metal ion chelators), their ability to modulate some cell signalling pathways and gene expression, and their ability to react with certain receptors. However, epidemiological studies exploring the role of flavonoids in human health remain insufficient to conclude on their protective role in human health. The biological activities of flavonoids greatly depend on their bioavailability. Quercetin conjugated with glucose appeared efficiently absorbed compared to quercetin as aglycone or conjugated with rutinoside. By contrast procyanidins and anthocyanins appear poorly absorbed. Different absorption mechanisms have been proposed. The content of flavonoids in plant foods is subject to numerous factors of variation. The main factor is certainly the cultivar within a given species. Other factors, such as light, soil nitrogen, maturity stage, could influence the flavonoid content. While a high consumption of fruits and vegetables along with a moderate intake of red wine should be encouraged, it does not unfortunately seem advisable to make any detailed recommendations on daily flavonoid intake given the present knowledge. | |
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