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Tea drinkers get five-a-day benefits

12-Jun-2003

A recommendation to drink tea would be consistent with dietary guidelines on foods to reduce the risk of heart disease, according to a researcher speaking at a recent conference on anti-aging.

Joseph A. Vita from the Boston University School of Medicine, highlighted the evidence showing that consumption of tea and other flavonoid-containing foods is associated with reduced risk of heart attack and stroke. There are also data to suggest that tea consumption reduces the extent of atherosclerosis in the aorta and the risk of recurrent complications following heart attack, he said.

 

However evidence to date does not explain the mechanisms responsible for tea's beneficial effects. Studies that attempted to demonstrate that tea has an antioxidant effect in vivo in human subjects have had mixed and largely negative results, noted Vita.

 

One possible explanation is related to the vascular endothelium, claimed the researcher. Recent studies have emphasized that the endothelium plays a central role in the regulation of vascular homeostasis. Loss of normal endothelial function may promote the development of atherosclerotic lesions and the conversion of quiescent plaques to active plaques that are responsible for acute ischemic syndromes, including myocardial infarction (heart attack) and stroke.

 

Recent studies indicate that short and long term exposure to ascorbic acid enhance endothelium-dependent vasodilation in patients with coronary artery disease.

 

Vita reports that in a randomized crossover clinical trial, tea consumption was found to improve endothelial function in patients with coronary artery disease. These findings were not caused by caffeine and appear to be specific for the endothelium, rather than vascular smooth muscle. Similar findings have been reported for patients with mild hypercholesterolemia, and for other flavonoid-containing beverages, he said.

 

Ongoing studies will examine the effects of specific components in tea in an attempt to determine how tea is exerting this effect. Tea consumption has beneficial effects on other clinically relevant aspects of the cardiovascular system. For example, tea consumption has been shown to reduce systemic markers of platelet activity and collagen-induced platelet aggregation.

 

Vita concluded that there is growing evidence that tea consumption has effects on endothelial function and possibly platelet function that would tend to reduce the risk of cardiovascular disease.

 

Vita was speaking at the 32nd AnnualMeeting of the American Aging Association (AGE ) in Baltimore, Maryland, which opened on June 9.

 

Technical themes included beneficial and harmful fats in foods, such as omega-3 and trans fatty acids; desirable chemical properties of fruits and vegetables, such as antioxidant and anti-inflammatory agents; and cellular oxidative stress affected by lifestyle habits, such as diet.