If you are interested in understanding in detail the benefits of green tea in relation to specific body functions and in comparison with other beverages, please download the White paper prepared by our experts. If you need any additional information, you are welcome to email us your questions and our experts will be happy to answer them for you.
According to Chinese legend, in 2737 B.C., Chinese Emperor Shen Nung sat next to a small cauldron of boiling water. Suddenly, he smelled a wonderful smell and found that leaves from the flowering camellia tree, Camellia sinensis, had fallen in the water. He sipped the water and discovered tea, which more than 4,000 years later, is the world’s second most popular drink. Over the past few decades, scientists have taken a closer look at the potential health benefits of tea.
Many of the health benefits of drinking tea come from the fact that tea contains high levels of antioxidants called polyphenols or flavonoids. These compounds are most prevalent in green and white teas, but are also present to varying degree in Oolong and black teas. Polyphenols can help the body protect itself against free radicals, molecules which occur in the environment and are naturally produced by the body, can cause damage to cells. Chronic damage by free radicals is one factor thought to contribute to the development of many chronic diseases including heart disease or cancer. Polyphenols scavenge cell-damaging free radicals, which are linked with cancer-causing genes and cause LDL cholesterol to form artery-clogging plaque. The polyphenols in tea possess 25 to 100 times the antioxidant potency of vitamins C and E. Antioxidants impair the ability of free radical cells to harm the molecules that make up our bodies.
Green tea has recently become the latest weapon in the war on weight. The results of some new studies are promising, finding that green tea can increase the rate of calorie burning, reduce body fat levels and even prevent excess weight gain. A human study showed that taking in the equivalent of 3 cups of green tea per day burned an additional 80 calories per day.
In a study of energy expenditure in men, those who took green tea extract containing EGCG plus caffeine three times daily burned about 80 more calories per day than those who didn't take the extract. Interestingly, taking caffeine with EGCG didn't have the same effect. Also, green tea extract was found to significantly increase 24 hour energy expenditure and fat oxidation in healthy men.
In another study, after three months of consumption of green tea extract by moderately obese patients, body weight decreased by 4.6 percent and waist circumference decreased by 4.48 percent. Researchers looked at group of flavonoids in tea and its effect on weight loss and body fat. They found significant weight loss and a significant reduction in total body fat in the people drinking tea flavonoids (equal to 3-4 cups of tea per day) when compared to participants drinking the placebo.
Green tea is believed to help prevent obesity by revving up the fat-burning effects of brown fat, sending glucose to muscle tissue where it’s more likely to be burned, rather than to fat tissue, and inhibiting the action of fat-digesting enzymes so the fat that you eat is less available to the body. Additionally, green tea is a satisfying, calorie-free beverage that can be substituted for sweetened beverages and is a delicious alternative to plain water in a healthy weight management plan.
Heart disease is a major cause of preventable disease and death in all regions of the world. In US, over 40% of all deaths are caused by heart disease which affects over 64 million people, almost one quarter of the US population. As part of a healthy lifestyle regular tea drinking may help maintain a healthy heart. Green tea is associated with a reduction in many risk factors for cardiovascular disease. Besides improving cholesterol values, it may help lower blood pressure, decrease blood stickiness, and prevent LDL oxidation (a crucial beginning step in the atherosclerotic process).
Human population studies have found that people who regularly consume three or more cups of tea per day have a reduced risk of heart disease and stroke. Three separate analyses of research showed that drinking three cups of tea daily reduced the risk for cardiovascular disease death or heart attack by about 10-12%. Clinical studies suggest that the risk reduction associated with tea consumption may be due to improvement in some risk factors for cardiovascular disease, including cholesterol levels, blood vessel function and a reduction in oxidative damage.
While researchers are still examining the various mechanisms by which tea flavonoids function, some studies suggest multifunctional mechanisms, meaning that several mechanisms work in tandem to collectively improve markers for cardiovascular health. Important areas of tea and cardiovascular health research include blood vessel and endothelial function, or the ability of the blood vessels to dilate to allow for proper blood flow, serum cholesterol levels and Low Density Lipoprotein (LDL) cholesterol oxidation. Each of these factors impacts the risk of heart attacks, stroke and cardiovascular disease. Study findings in the area of tea and the reduction in cardiovascular disease risk include the following:
Researchers believe that green tea helps reduce cholesterol by lowering its absorption in the digestive tract and increasing its excretion. A study conducted by United States Department of Agriculture (USDA) showed that the effect of tea on 15 mildly hypercholesterolemic patients following a "Step I" type diet moderately low in fat and cholesterol. After three weeks, the patients with five servings of black tea per day reduced LDL ("bad") cholesterol by 11.1 percent and total cholesterol (TC) by 6.5 percent compared to placebo beverages.
Italian researchers studying two groups of volunteers following a controlled diet found that those who drank two cups of green tea (about 250 mg of catechins) per day for 6 weeks reduced their LDL "bad" cholesterol by an average of 13 mg/dl.
A double blind, randomized, placebo-controlled study involving 240 people with mildly to moderately-elevated cholesterol found that taking 375 mg of theaflavin-enriched green tea extract daily for 12 weeks caused a reduction in total cholesterol of 11.3% and in LDL cholesterol of 16.4%, while the HDL "good" cholesterol increased by 2.3%.
Animal studies have shown that even when consuming a diet rich in lard and cholesterol, rats who receive green tea catechins have much lower cholesterol levels than those who don't receive the catechins.
Research studies suggest that the flavonoids in tea could play a role in human cancer risk reduction possibly by combating free radical damage, inhibiting uncontrolled cell growth (cell proliferation), and by promoting programmed cell death (apoptosis). Leading scientists worldwide are actively studying these potential mechanisms, and clinical trials and population studies are underway. More evidence is needed before any definitive conclusions can be drawn. Recent findings include:
A healthy immune system protects the body from infection and disease. The researchers identified a substance in tea, L-theanine – a unique amino acid, which primes the immune system in fighting infection, bacteria, viruses and fungi. This suggests that regular tea consumption may help support the body’s immune system. Researchers from the Brigham and Women’s Hospital and Harvard University recently published new data indicating that theanine can help the body ward off infection and disease and may strengthen the immune system.
A subsequent human clinical trial showed that certain immune cells of participants who drank five cups of black tea a day for two to four weeks secreted up to four times more interferon, an important part of the body’s immune defense, than at baseline. Consumption of the same amount of coffee for the same duration had no effect on interferon levels. According to the authors, this study suggests that drinking black tea provides the body’s immune system with natural resistance to microbial infection. While research on effects of tea on the body’s immune system and its potential to help protect the body is just emerging, experts are encouraged by these promising results.
Tea may also contribute to oral health. The flavonoids in tea may inhibit the plaque-forming ability of oral bacteria and the fluoride in tea may support healthy tooth enamel. Tea is a good source of fluoride, a mineral that helps protect teeth by strengthening tooth enamel and combating cavities. Research studies indicate that tea flavonoids may inhibit the plaque-forming ability of oral bacteria. Tea does this through an anti-bacterial effect on Streptococcus bacteria, by preventing the bacteria’s adherence to teeth and by limiting of the synthesis of sticky glucan which in animal studies has been shown to help prevent cavities.
A recent study conducted at the New York University Dental Center examined the effects of black tea extract on dental caries formation in hamsters. Compared to those who were fed water with their food, hamsters which were fed water with black tea extract developed up to 63.7 percent fewer dental caries.
Although high caffeine intake has been suggested to be a risk factor for reduced bone mineral density (BMD), research indicates that drinking tea does not negatively affect BMD, and while it may be too soon to state definitively, findings suggest that tea may even play a role in bone health. A study published recently in the American Journal of Clinical Nutrition found that older women who drank tea had higher BMD measurements than those who did not drink tea. The researchers concluded that the flavonoids in tea might influence bone mass and that tea drinking may reduce the risk of osteoporosis. Another recent study found that habitual tea-drinking was seen to have a significant beneficial effect on the BMD of adults (30 years and older), especially in those who had been habitual tea-drinkers for six or more years. Studies in adolescent and postmenopausal women found no relationship between caffeine intake and bone health.
According to a study conducted by the University of Arizona, participants who drank iced black tea and citrus peel had a 42 percent reduced risk of skin cancer. Black tea consumption is associated with a significantly lower risk of squamous cell carcinoma (SCC), a form of skin cancer; tea concentration (strength), brewing time and temperature all influence the potential protective effects of hot black tea on SCC. Oral consumption of green or black tea decreased the number of tumors in mice following exposure to UV radiation. Green tea polyphenols may have cancer preventive potential, especially in the case of solar UV-induced cancer. Research suggests that compounds in green tea may protect skin from ultraviolet (UV) radiation-induced damage when applied topically. Topical treatment of green tea polyphenols on human skin prior to UV exposure inhibited indicators of DNA damage, thus inhibiting photocarcinogenesis, or UV-induced skin cancer. Experiments that show that administration of green tea, Black Tea or specific flavonoids in tea inhibited the growth of established nonmalignant and malignant skin tumors in tumor-bearing mice. In addition, oral administration of Black Tea inhibited DNA synthesis and enhanced cell death (apoptosis) in both nonmalignant and malignant tumors in tumor-bearing mice.