Flavonoid rich foods such as tea, red wine and cocoa are increasingly being seen as beneficial to the health. Flavonoids are a group of polyphenolic compounds that possess in vitro antioxidant capabilities, and may confer antioxidant capacity to animal tissue once consumed. In addition, gene regulatory effects for flavonoids have been suggested. Tes is an important source of the catechin group of flavonoids (also failed flavan-3-ols), but also contains other flavonoids such as the flavonol quercetin. Epidemiological studies suggest that tea drinkers are protected from certain diseases and this has been suggested to be due to the flavonoid content of the tea, particularly the catechins. Because tea is protective of cardiovascular disease, researchers are interested at investigating the effects of tea on parameters of cardiovascular risk such as blood pressure. Flavonoids may improve blood pressure because the antioxidant protection they confer may improve flow mediated dilation of arteries, thus improving flow dynamics.
In order to determine the effects of epicatechin and quercetin in tea, researcher administered them in purified form to a group of healthy men and women aged 40 to 80 years1. Subjects received 100 mg (-)epicatechin or 160 mg quercetin-3-glucoside or a placebo capsule for 4 weeks. All subject received each treatment in a random order in a double blind fashion. The results of the study showed that epicatechin was not able to improve flow mediated dilation, blood pressure or arterial stiffness, but did improve fasting plasma insulin and insulin sensitivity. Quercetin-3-glucoside caused no measurable changes in any of the parameters measured. Epicatechin may therefore have insulin sensitising effects, as has been shown for antioxidant previously, particularly the antioxidants in herbs and berries. In the long term, this may confer significant health effects. It is also worthy of note that effects were seen in healthy individuals, had subjects at risk of cardiovascular disease been used, the effects may have been greater.
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