Another study, led by Theodore Fotsis, Ph.D., of the University of Ioannina, Greece, found that many common citrus flavonoids inhibited angiogenesis, the growth of blood vessels in tumors. One citrus flavonoid in particular, quercetin, has attracted considerable interest for its possible role in preventing heart disease and cancer. High intake of this flavonoid was associated with a 53 percent lower risk of coronary heart disease and a 38 percent lower risk of death from all causes. Green Tea Flavonoids Green tea and, to a lesser extent, black tea are rich sources of still another group of flavonoids called catechins. Population-based studies have shown that tea drinkers have a lower than average risk of heart disease, stroke, and several cancers including esophageal, stomach, and lung cancers.
Cancer cells use the enzyme urokinase to invade cells and metastasize.
According to Jerzy Jankun, Ph.D., of the Medical College of Ohio, Toledo, the EGCG in green tea is a potent inhibitor of urokinase activity. A single cup of green tea contains enough EGCG to temporarily inhibit urokinase activity - and is safer than synthetic drugs that block urokinase activity. Isoflavones Over the past three years, more than 1,000 scientific studies have been published on soy flavonoids, technically known as isoflavones. These isoflavones function as antioxidants, and they seem to possess properties that distinguish them from other types of flavonoids. The principal soy isoflavones are genistein, daidzein, and glycitein.