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G. WILLIAMSON, Nestlé Research Center, Nestec Ltd, Vers-chez-les-Blanc, PO Box 44, Lausanne 26, 1000, Switzerland Although there are now many human clinical studies that show the health benefits of phytochemicals as assessed by measurement of biomarkers, many questions remain to be answered. Studies using a variety of biomarkers after consumption of polyphenols by volunteers have indicated the following effects: soy isoflavones improve bone health in post-menopausal women; catechins, including green tea catechins, improve biomarkers of antioxidant status and affect energy metabolism; procyanidins from foods such as grapes, apples, cranberries, cocoa, and red wine, have pronounced effects on the vascular system. Animal studies have also indicated numerous effects of phytochemicals on health such as the anti-carcinogenic effect of green tea catechins. Many recent in vitro studies have elucidated some of the mechanisms involved in the physiological actions of phytochemicals. A decade ago, it was believed that the action of phytochemicals was due to their free- radical scavenging properties. Although these properties undoubtedly exist, it is quite clear that the effects on health are mechanistically much more complex, and involve interaction with receptors, transporters, metabolic enzymes, and changes in the transcriptome, proteome, and metabolome. This means that the uses of biomarkers such as measurement of plasma antioxidant activity, although useful, do not in any way tell the whole story. For the estimation of biological activity of phytochemicals in the 21st century, it is necessary to consider a wide variety of sophisticated biomarkers in order to assess the effects of phytochemicals on health in humans.
Session 45, Health benefits of fruits and vegetables: Biological activity of phytonutrients
2005 IFT Annual Meeting, July 15-20 - New Orleans, Louisiana |