Flavonoids : changing views on nutritional benefits

Flavonoids in fruits and vegetables are phytochemicals that were commonly thought of by most nutritionists as strong antioxidants, hence their beneficial effects on human health, at least, that's what we were led to believe. According to research performed at the Linus Pauling Institute, this could be far beside the truth. Flavonoids certainly are healthy, but probably for other reasons than as 'rust removers'. I've always felt that the whole 'free radical damage/antioxidant therapy' story was, first, a little too simplistic, and second, 'gefundenes Fressen' for eager nutraceuticals marketing machines. What follows makes more sense for me....

As it looks, flavonoids are indeed strong antioxidants in the test tube, but, once ingested as part of the diet, are highly metabolized in humans, and in this process lose most of their antioxidant activity. But they do show a strong influence on cell signalling and gene expression, with relevance to both cancer and heart disease. By following the activity of flavonoids in the human body, scientists discovered that what really happens is that the body wants to get rid of these 'foreign compounds', and this process induces phase II detox enzymes that help in eliminating mutagens and carcinogens. Flavonoids also increase production of nitric oxide synthase, resulting in more 'relaxed' and less inflamed blood vessels, and lower blood pressure. Both these protective mechanisms could explain the results of many studies showing that adequate intake of fruits and vegetables, but also intake of flavonoid-containing coffee, wine, tea, chocolate, etc... does indeed offer protection against cancer, heart disease and other degenerative conditions.