More than 200-300 independent health studies have been conducted related to the benefits of tea. Most have been on green and black teas.
Health Benefits of Tea
Tea is rich in polyphenols, tannin, and flavonols (often termed catechins), fluoride, and vitamin C, P, K, and B. Although tea contains caffeine, the amounts are far less than those in coffee and produce a softer, beneficial effect. Studies suggest that as few as four servings of tea a day may have a positive impact on your health.
Antioxidants in tea are able to neutralize the damaging effects of oxygen and free radicals that are present in the body. Antioxidants slow or prevent cell damage from exposure to oxygen by creating a barrier around cell tissue. (Leenen R, Roodenburg A, Tijburg L, Wiseman S. A single does of tea with or without milk increases plasma antioxidant activity in humans. Eur J Clin Nutr 2000;54(1):87-92.) Recent studies show that polyphenols found in green tea appear in greater concentrations in white tea, helping to destroy bacteria and other organisms that cause disease. (Pace University's Dyson College of Arts & Sciences)
Recent studies show that polyphenols found in green tea appear in greater concentrations in white tea, helping to destroy bacteria and other organisms that cause disease. (Pace University's Dyson College of Arts & Sciences)
The EGCG rich polyphenols in green tea protect skin from ultraviolet radiation damage, preventing skin tumor formation. The same compound is found to inhibit enzymatic reactions that break down collagen and elastin in skin.
Green Tea has been found to inhibit the growth of esophageal and stomach tumors in mice. Green and black tea could inhibit the development of pre-cancerous lesions as well. (Saitama Cancer Center and the Department of Biochemistry at the Bunri Tokushima University) A recent study showed that a compound in black tea called TF-2 caused colorectal cancer cells to “commit suicide”; normal cells were unaffected. (Imai K, Nakachi K. Cancer-preventative effects of drinking green tea among a Japanese population, Prev med 1997;26:769-75.)
Present at higher quantities in green tea, the antioxidant epigallocatechin gallate (EGCG) is the focus of cancer research worldwide and identified by scientists as a cancer-fighting compound. One Japanese study highlighted a reduction in the growth of human lung cancer cells after the consumption of two to three cups of green tea. (Nature, Structure, and Molecular Biology, 2004)
Improved Cardiovascular Health and Reduced Risk of Stroke
A study undertaken found that of 340 men and women who had suffered from heart attacks, those who drank a cup or more of black tea daily had a 44% lower risk of repeated heart attacks compared to non-tea drinkers. Flavonoids in tea are theorized to improve the lining of blood vessels, which may account for the decreased risk. Studies show that drinking black tea helps to prevent narrowed or clogged arteries that lead to ischemic heart disease, heart attack, or stroke. (Sesso H, Gaziano J, Buring J, Hennekens C. Coffee and tea intake and the risk of myocardial infarction. Am J Epidemiol 1999;149(2):162-7)
Reduces “bad” Cholesterol
One study suggests black tea to reduce LDL-cholesterol (“bad cholesterol”). Tea polyphenols may limit the absorption of cholesterol in the intestine, thus reducing the cholesterol levels in the blood. Reducing “bad” cholesterol LDL deposits, tea elevates HDL, or “good” cholesterol. Green tea, particularly oolong, may prevent arteriosclerosis. (Kono S, Shinchi K, Wakabayashi K, et al. Relation of green tea consumption to serum lipids and lipoproteins in Japanese men. J Epidemiol 1996;6(3):128-33.)
Oral Health and Prevention of Tooth Decay and Bad Breath
Flavonoids (mainly catechins) found in green tea, have exhibited inhibitory effects on the growth of cariogenic bacteria by inhibiting the adherence and growth of plaque bacteria at the tooth surface. Polyphenols found in both green and black tea can block bacteria from producing foul-smelling compounds such as hydrogen sulfide in the mouth. Studies show the tannin and fluoride content present in tea prevents tooth decay. (Otake S, Makimura M, Kuroki T. Anticaries effects of polyphenolic compounds from Japanese green tea. Caries Res 1991;25:438-443.)
Green tea may inhibit the development of arthritis. In one study, mice given green tea polyphenols were significantly less likely to develop arthritis. The study was conducted on 36 mice. Of the 18 mice that received the green tea, only eight (44%) developed arthritis. Among the 18 mice that did not receive the green tea, all but one, or 94% developed arthritis. (Haggi TM, Anthony DD, Gupta S. Prevention of collagen-induced-arthritis in mice by a polyphenolic fraction from green tea. Proc Natl Acad Sci USA 1999;96:4524-4529.)
Green tea’s antioxidant EGCG may stimulate the body to burn calories, notably fat. In a recent study, a daily dose of 270 mg EGCG (the amount 2-3 cups of green tea) caused men to burn 4% more energy – about 80 extra calories a day. (Dulloo AG, Seydoux J, Girardier L, Chantre P, Vandermander J. Green tea thermogenesis: Interactions between catechin-polyphenols, caffeine, and sympathetic activity. Int J Obes Relat Metab Disord 2000;24:252-258.)
Green tea extract has been shown to significantly increase energy expenditure (a measure of metabolism) and may have a significant effect on fat oxidation. (Dulloo A, Duret C, Rohrer D, et al. Efficacy of a green tea extract rich in catechin polyphenols and caffeine in increasing 24-h energy expenditure and fat oxidation in humans. Am J Clin Nut 1999;70(6):1040-5.)
Reduced Risk of Kidney Stones
In a study of more than 81,000 women 40 to 65 years of age, it was concluded that 8 fluid ounces of tea consumed daily actually lowers the risk of developing kidney stones by 8%. Furthermore, tea acts as a diuretic, stimulating the flow of urine), promoting better kidney function and aids digestion. (The Third International Scientific Symposium on Tea & Human Health)
Slows the Aging Process
It has been shown that Green tea reduces infection and the stresses of bacteria on the system thus significantly retarding the aging process. (The Department of food and Nutritional Sciences, University of Shizuoka, Japan.)
Blood cells from tea drinkers respond 5 times faster to germs than those of coffee drinkers. (Brigham and Women’s Hospital in Boston and Harvard Medical School) One way to measure the strength of an immune system is to measure the production of antibacterial proteins in the body. Higher levels of these proteins are associated with healthier immune systems that are better at warding off illness and disease than a weak one. A study comparing the production of these proteins in coffee and tea drinkers found that the group drinking 2.5 cups of black tea per-day exhibited production levels that were five times higher than those of the coffee drinkers. (Kamath A, Wang L, Das H, Li L, Reinhold V, Bukowski J (2003) “Antigens in tea-beverage prime human Vgamma 2Vdelta 2 T cells in vitro and in vivo for memory and nonmemory antibacterial cytokine responses” Proc Natl Acad Sci USA 100 (10): 6009-14)
Holds Promise as HIV Therapy
Epigallocatechin gallate (EGGG), an active ingredient in tea, has antiviral, antioxidant and antibacterial properties that are now being studied in hopes that it helps inhibit the HIV virus. (Kawai K, Tsuno NH, Kitayama J, Okaji Y, et al. Epigallocatechin gallate, the main component of tea polyphenol, binds to CD4 and interferes with gp120 binding, J Allergy Clin Immunol 2003;112:951-957.)