Black Tea Reduces Cholesterol
Adding five cups of black tea per day to a moderately low-fat diet reduces serum cholesterol levels, according to a new study published in the Journal of Nutrition (2003;133:3298S–3302S).
Tea leaves (Camellia sinensis) contain a number of plant constituents known as flavonoids. These flavonoids, which are present in beverages made from tea leaves, have strong antioxidant activity and might also prevent the absorption of cholesterol from the digestive tract. Because of these effects, it has been suggested that consumption of tea or tea flavonoids might reduce the risk of developing cardiovascular disease. Some studies have found that black tea consumption protects against coronary artery disease and stroke, but others have not. In one study, total cholesterol levels were reduced in people drinking large amounts of black tea; however, several other studies have found no effect of black tea consumption on cholesterol levels.
In the current study, fifteen healthy people with mild hypercholesterolemia (elevated cholesterol levels) were randomly assigned to one of two treatment groups. Participants in both groups were placed on controlled diets designed to maintain their weight and to comply with the National Cholesterol Education Program Step 1 Diet, which is moderately low in total fat, saturated fat, and cholesterol. After two weeks on the controlled diets, each group was given five cups of either a black tea or a placebo beverage to consume per day for three weeks. These beverages were then removed from the diets for four weeks, following which each participant consumed the other beverage for three additional weeks. Finally, the study was repeated using a placebo drink that provided the same amount of caffeine as that found in the tea.
Total cholesterol, HDL ("good") cholesterol, LDL ("bad") cholesterol, and several other lipid levels associated with risk of heart disease were measured at the end of each treatment phase during the study. Total cholesterol levels were 3.8% lower after black tea consumption than after placebo, and 6.5% lower than after placebo plus caffeine. LDL-cholesterol levels in tea drinkers were 7.5% lower than in those receiving placebo and 11.1% lower than in those receiving placebo plus caffeine. Other lipid levels were not significantly affected by black tea consumption.
The results of this study show that black tea lowers cholesterol levels in people with mild hypercholesterolemia who are eating a Step 1 diet. Previous studies that did not find a link between black tea consumption and cholesterol levels did not control for diet as rigorously. The effects of black tea on cardiovascular risk in people with normal or very high cholesterol levels, and its effect in people eating other specific diets, remain to be determined.
Maureen Williams, ND, received her bachelor’s degree from the University of Pennsylvania and her Doctorate of Naturopathic Medicine from Bastyr University in Seattle, WA. She has a private practice in Quechee, Vermont, and does extensive work with traditional herbal medicine in Guatemala and Honduras. Dr. Williams is a regular contributor to Healthnotes Newswire.
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