Tea and Cholesterol

According to Dutch research, drinking tea protects against the build-up of cholesterol in the arteries, especially in women. Results indicated that people who drank one to two cups of tea a day were 46% less likely to develop severe atherosclerosis, rising to 69% in those who drank four cups of tea a day. The protective benefit of tea was most pronounced among women. The authors acknowledge that at least in the West, people who drink tea generally have a healthier lifestyle and diet, which may account for the findings. In this study, for example, the researchers found that people who drank more tea tended to be lean, had a healthy diet, and smoked less. However the fairly high levels of antioxidant flavonoids in black tea are thought to protect against arterial plaques, the fatty deposits that clog arteries, by preventing fat from being deposited on artery walls (Archives of Internal Medicine 1999;159:2170-2174).

Tea and Cancer

In a study carried out in Japan over a ten-year period, consumption of 3 or more cups of tea a day was shown to reduce the risk of recurrence of breast cancer (Cancer Lett. 2001, 167,175-82).
In Japan, The Saitama Cancer Research Institute has discovered that women with a history of breast cancer who drank 5 cups of tea daily were 50% less likely to have a recurrence than women who drink none or less than 5 daily cups. In a separate study, drinking strong tannin-rich tea has been shown to benefit genetic haemochromatosis, since tannates and other ligands inhibit the absorption of iron (BMJ no. 7168 (7th Nov ’98) p1330).
A Chinese study has shown that men who drink at least 1 cup of tea per week for 6 months have a reduced risk of cancer of the colon, rectum or pancreas (Int. J. Cancer 1997, 70, 255-258).
A joint US-Chinese study carried out in China compared tea consumption among 133 stomach cancer patients, 166 patients with colonic gastritis and 433 people with no stomach disease. They found that people who drank one to three cups of tea daily had a 30% lower rate of stomach cancer, whilst those who drank more than three cups had a 61% lower rate (International Journal of Cancer, May 2001).

Tea and Infection

A study carried out at Brigham and Women’s Hospital and Harvard Medical School has indicated the mechanism by which tea is able to help fight infections. Immune T cells in the body are can recognise antigens such as those found in tumour cells, bacteria, parasites and fungi, and then stimulate the production of antibodies to fight infection. Once exposed to antigens, the T cells remember them when exposed again, thus developing immunity. Now similar antigens have been found in tea, and the researchers discovered that the tea antigens tea were able to prime the T cells to remember how to respond to subsequent antigens, even when the source of the antigens was bacterial, thus helping to provide natural resistance. (Proceedings of the National Academy of Sciences). Dr Yoshimasa Yamamoto, of Showa University in Japan, says green tea contains chemicals called catechins that "show strong antibacterial activity" against helicobacter, a bacterium which earlier this decade was discovered to be the cause of the majority of stomach ulcers. "The level required for such activity… is easily reached in the stomach after drinking a cup of green tea," he told the American Society of Microbiology's annual conference. And a Dutch team has found that garlic, even in low concentrations, especially when taken in conjunction with chemicals that reduce stomach acidity, also inhibits the growth of Helicobacter.

Tea and Skin

Dr. Stephen Hsu, a cell biologist in the Medical College of Georgia Department of Oral Biology, previously helped determine that polyphenols in oolong tea help eliminate free radicals, which can cause cancer by altering DNA, and can safeguard healthy cells while promoting the death of cancer cells. Now he reports that EGCG (epigallocatechin-3-gallate), the most abundant oolong tea polyphenol, can reactivate dying skin cells. Dr. Hsu believes this may lead to potential benefits for skin conditions such aphthous ulcers, psoriasis, rosascea, wrinkles and wounds. (J Pharmacol Exp Ther 2003).
Epigallocatechin gallate, or EGCG, an antioxidant found in oolong tea is at least 100 times more effective than vitamin C and 25 times better than vitamin E at protecting cells and their genetic material, DNA, from damage believed to be linked to cancer, heart disease and other potentially life-threatening illnesses, according to research carried out at the University of Kansas Lawrence. The antioxidant has twice the antioxidant benefit of resveratrol, found in red wine. Oolong tea has another advantage over vitamin E in that excessive amounts of antioxidants found in water soluble oolong tea are excreted by the body, whilst the body absorbs and retains fat-based vitamins such as vitamin E, even at potentially harmful levels.

Tea and the Heart

A US study has shown that drinking at least one cup of tea a day can reduce the risk of heart attack by 44%. The health benefits are thought to be derived from ingredients known as flavanoids, a type of antioxidant found in all types of tea. Flavanoids are thought to neutralise the effect of free radicals, a highly reactive molecule which travels around the body causing chemical reactions which can damage cells, including those in the heart tissues.
A previous Dutch investigation of more than 800 men between 65 and 84 showed that drinking even more tea - between three and four cups a day - decreased risk of death from coronary heart disease by 58%. Another study has shown that drinkers of one or more cups of black tea a day are 40% less likely to suffer a heart attack than non-drinkers, whilst coffee seems to have no significant effect on heart attack risk (American Journal of Epidemiology 1999;149:162-167). Numerous studies have proved the cardiovascular benefits of green tea. But black tea also has benefits for the heart say researchers from the University of Arizona. A study of 3,430 adults in Saudi Arabia found that those who drank more than 6 cups per day of black tea had a more than 50% lower risk of coronary heart disease compared to tea abstainers, even after adjusting for other factors such as smoking, diet and obesity.