Green tea treatment appears to reduce heart disease risk factors

A derivative of the green tea leaf may help reduce risk factors for heart disease, including bad cholesterol and high blood pressure, report researchers.

A study on Tegreen, a tea polyphenols product containing more than 65 per cent tea catechins, found that the product is capable of improving glucose and lipid metabolism in an obese rat model.

Researchers suggest that it could be used to treat Metabolic Syndrome X, the term used to describe a group of heart disease risk factors, including high levels of abdominal fat, bad cholesterol, high blood pressure, and abnormal glucose metabolism. Also known as Insulin Resistance Syndrome, the symptoms are thought to run in families with a history of type 2 diabetes.

Researchers from the Pharmanex Beijing Pharmacology Center, Beijing, China, report however that in a new animal model study Tegreen improved lipid and glucose metabolisms, enhanced insulin sensitivity, and balanced the metabolic rate of fat deposit and fat burning. They will present their findings at the Experimental Biology meeting taking place next week in San Diego, US.

Tegreen powder, containing more than 97 per cent tea polyphenols or more than 65 per cent tea catechins, was tested on 44 female Sprague-Dawley rats, randomly placed in one of four experimental groups.

Rats in a normal diet placebo group were fed normal rat forage. The other rats were fed a high-calorie diet, including a high-calorie diet placebo, for a period of 56 days. Two treatment groups were given either high dose (75mg/kg) Tegreen or a lower dose of 25mg/kg. Following fasting of ten hours, orbital blood samples were collected to examine fasting serum glucose, serum triglycerides, plasma insulin, and plasma glucagon.

Glucose insulin index and ratio of insulin to glucagon were calculated and abdominal adipose tissue was isolated and weighed.

The researchers report that rats fed the high-calorie diet significantly increased their weight of abdominal fat tissue and ratio of insulin to glucagon, indicating increased adipose deposit, and decreased fat burning. The glucose-insulin index was lowered by 13 per cent in rats on the high calorie diet, indicating reduced insulin sensitivity or insulin resistance and excessive visceral adipose accumulation. These metabolic changes suggested that rats on the experimental diet developed Metabolism Syndrome X.

After the eight-week Tegreen treatment, fasting blood glucose was decreased significantly by 21.5 per cent in rats on the low-dose treatment, and 15.7 per cent in rats on high-dose Tegreen. Fasting plasma insulin also decreased, by 40.7 per cent in rats given Tegreen at a dose of 25 mg/kg, and by 31.2 per cent at the higher dose.

Also, the insulin index increased significantly in rats given Tegreen, suggesting enhanced insulin sensitivity, while fasting serum TG was significantly decreased (31 per cent and 54.3 per cent, respectively) in rats receiving the test product.

There were also notable decreases in the weight of abdominal adipose fat relative to body weight and there were decreases in ratio of insulin to glucagons (49.9 per cent at a dose of 25 mg/kg, and by 43 per cent at a dose of 75 mg/kg), suggesting increases in fat burning and decreases in visceral fat deposit.

The researchers concluded that results clearly show that Tegreen intervention can significantly decrease visceral fat deposit and increase insulin sensitivity, presumably touching one of the pathological root causes of the potentially deadly Metabolism Syndrome X. If these results can be repeated in a human trial, the treatment may have considerable advantages for a large proportion of the developing world's population.