Currently, tea in the form of green or black tea, next to water, is the most widely consumed beverage in the world. According to Chinese legends, tea was discovered by the Emperor Shen Nong in about 2700 BC, when a gust of wind blew tea leaves into a kettle of boiling water.
Teas contain polyphenols which act as antioxidants and exhibit numerous biochemical activities. Tea polyphenols consist mostly of catechins, the most powerful of which is epigallocatechin gallate (EGCG) which is found only in green tea. Since ancient times green tea has been considered a health-promoting beverage and currently researchers find more convincing proof of healing qualities of green tea.
Based on the growing range of studies that research health properties of green tea, I made this list of clear benefits you can get with regular green tea drinking.
1 Longevity
Green tea may protect against death from all causes, especially cardiovascular disease. Japanese researchers[1] analyzed data from a National Cohort Study that began in 1994 and had over 40,000 participants, age 40 to 79, who began the study free of stroke, heart disease and cancer. People were followed for up to 11 years.
Compared with participants who consumed less than 1 cup of green tea per day, those drinking 5 or more cups a day had a significantly lower risk of death from all causes, especially lower risk of dying from cardiovascular disease and stroke. The findings might explain in part the reason why the Japanese live longer than people in any other country. However, this study found no cancer prevention benefit of green tea.
2 Improved memory and learning ability
One of the important health benefits of regular green tea drinking is improved memory and learning ability. Population-based study[2] in Japan revealed that high green tea drinking maintains cognitive function. Also, according to the results from animal studies[3-4], green tea consumption may enhance learning and memory ability.
The main components of green tea that are thought to work on improving brain function are polyphenols, epigalochatechin-3-gallate (EGCG), a very strong antioxidant. The high use of oxygen during the metabolic processes leads to the generation of a large number of free radicals (a highly reactive molecules). EGCG can penetrate the brain's blood barrier and is able to enact its antioxidative affects on the free radicals that cause damage in the brain.
3 Weight control
There is strong evidence that green tea has fat-burning properties and promotes weight loss, especially when combined with increased physical activity and a healthy diet. Green tea polyphenols are known to promote weight loss by increasing the metabolism of fats by the liver (thermogenic effect), inhibiting lipase (fat absorption enzyme) in the digestive tract, and providing a feeling of satiety and fullness[5]. Recent high-quality study[6] demonstrated that green tea can reduce body weight in obese persons by increasing energy expenditure and fat oxidation. The results of new Japanese study[7] also confirm fat-burning properties of green tea. Researches found that continuous ingestion of a green tea extract high in catechins led to a reduction in body fat, systolic blood pressure, and LDL cholesterol, that in its turn contributes to a decrease in obesity and cardiovascular disease risks.
4 Skin protection from Ultraviolet
Green tea polyphenols protect the skin against the adverse effects of ultraviolet radiation such as UV-induced sunburn, UV-induced immunosuppression and photoaging of the skin. They exert their photoprotective effects by various cellular, molecular and biochemical mechanisms[8-9]. Also, green tea polyphenols protect the skin by improving the elastic tissues[10].
5 Cholesterol-lowering effect
Green tea lowers total cholesterol and LDL cholesterol levels and improves the ratio of HDL cholesterol to LDL cholesterol. Studies[11-13] have shown that people who drink green tea as a daily part of their diet have lower cholesterol levels than those who do not drink any green tea.
Researchers believe that one of the underlying mechanisms by which green tea lowers blood cholesterol levels is by reducing lipids absorption in the digestive tract and promoting their excretion from the body[14].
6 Protection against dabetes and regulation of blood glucose levels
Green tea has been traditionally used to control blood sugar. Recent evidence also suggests green tea may help regulate the blood sugar and reduce the risk for type 2 diabetes. People who are frequent drinkers of green tea (>6 cups per day) are less likely to develop diabetes than those who drink less than 1 cup of the beverage per week[15]. Green tea antidiabetic effect may be partly explained by its caffeine content.
New Japanese study[16] demonstrated that daily intake of green tea extract lowered the hemoglobin A1c level in people with borderline diabetes, that indicates the increased body's ability to utilize blood sugar. Hemoglobin A1c is a test that measures the amount of glycosylated hemoglobin in blood. Glycosylated hemoglobin is a molecule in red blood cells that attaches to glucose, a blood sugar. People have more glycosylated hemoglobin if they have more glucose in the blood.
7 Heart protective effects: Asian paradox
Green tea may protect against heart disease. Researchers say green tea might explain the "Asian paradox" - when people living in Asian countries smoke cigarettes heavily, but have relatively low incidence of heart disease. Japanese studies[17-19] confirm that regular green tea consumption provides protection against coronary artery disease. The more green tea people consume the less likely they are to have coronary artery disease. Underlying mechanisms for the heart beneficial effects of tea include vasculoprotective, antioxidative, antithrombogenic, anti-inflammatory, and cholesterol-lowering properties of tea flavonoids.
There is a clear evidence that consumption of green tea can promote cardioprotection and reduce heart muscle cells death after a heart attack (myocardial infarction)[20]. The primary catechin in green tea, EGCG, prevents heart muscle damage by blocking the activation of inflammation-related compounds that promote the oxidative damage that kills heart cells in heart attack. EGCG also appears to speed up the recovery of heart cells.
8 Anti-hypertensive effect
Green tea lowers blood pressure and helps prevent hypertension. Tea increases body's production of nitric oxide, which dilates arteries and thereby reduces blood pressure[21-22]. A study[23] published in the July 2004 issue of the Archives of Internal Medicine found that among persons consuming tea regularly for at least one year, the risk of developing high blood pressure was 46% lower among those who drank 1/2 cup to 2 1/2 cups per day, and 65% less among those consuming more than 2 1/2 cups per day.
9 Stroke prevention
Green tea shows promise in the prevention of stroke[1, 24]. Furthermore, the green tea polyphenols, particularly EGCG, have been shown to protect brain cells from destructive processes following stroke[25-26].
10 Prevention of cognitive impairment and neurodegenerative diseases (Alzheimer's and Parkinson's Diseases)
Green tea is neuroprotective, and may reduce the risk of degenerative disorders of the central nervous system, such as cognitive decline, Alzheimer's disease and Parkinson's disease. Green tea catechin polyphenols produce several neuroprotective activities like iron chelation, scavenging of radicals, activation of survival genes and cell signaling pathways, anti-inflammatory activities, and inhibitory action on Abeta fibrils/oligomers formation[27, 29]. All of these biological effects result in a lessening of damage to brain cells.
Recently, Japan scientists have discovered that people who consumed more than 2 cups of green tea a day had a 50% lower chance of having cognitive impairment, in comparison to those who drank fewer than 2 cups a day, or who consumed other tested beverages[28].
11 Atherosclerosis prevention
Regular green tea drinking may be beneficial for the prevention and treatment of atherosclerosis, a disease in which plaque builds up on the insides of the arteries[30]. Green tea has been shown to effectively lower the risk of atherosclerosis by lowering LDL cholesterol, triglycerides, lipid peroxides (free radicals that damage LDL cholesterol and other lipids) and fibrinogen (a protein in the blood involved in the formation of blood clots). Green tea is a powerful antioxidant and protects LDL cholesterol from oxidation[31-32]. Oxidized cholesterol gets sticky and tends to cling to the walls of he arteries, leading to the development of atherosclerosis.
12 Anticlotting effect
Green tea also appears to prevent the formation of blood clots (thrombosis). Green tea catechins produce potent antithrombotic effect by inhibition of platelet aggregation (blood clot formation)[33].
13 Increased exercise endurance
Animal studies indicate that green tea increases exercise endurance. Green tea catechins increase metabolic capacity and utilization of fatty acid as a source of energy in skeletal muscle during exercise[34].
14 Protection from negative effects of smoking
According to the creditable study[35] regular green tea drinking may protect smokers from oxidative damages and reduce cancer risk or other diseases caused by free radicals associated with smoking. Green tea consumption may be effective to prevent future cardiovascular disorders in chronic smokers[36-37].
15 Bone mineral density increase
Green tea drinking may prevent osteoporosis and bone loss. Researchers at the University of Tokyo[38] have shown that drinking green tea may increase bone mineral density. Australian researchers[39] report that bone mineral density is 2.8% greater in tea drinkers than non-drinkers. In a 5-year prospective trial not only was tea drinkers' total BMD 2.8% higher than non-tea drinkers, but over the course of 4 years, tea drinkers lost an average of 1.6% of their total hip bone mineral density , while non-tea drinkers lost more than twice as much (4%).
16 Tooth decay (dental caries) prevention
Green tea is effective and proven remedy to prevent tooth decay. It kills the bacteria that cause dental plaques and halitosis (bad breath) and increases the acid resistance of tooth enamel [40-42].
17 Arthritis
Green tea may help people with arthritis by reducing inflammation and slowing cartilage breakdown[43].
18 Antimicrobal activity
Green tea catechins have anti-bacterial, anti-viral and anti-fungal activity[44]. These include some types of salmonella, influenza virus and herpes simplex. Its bacteria-destroying abilities can help prevent food poisoning. A US study[45] suggests a component of green tea may be useful in treating severe sepsis, an abnormal immune system response to a bacterial infection.
19 Liver protection
Green tea appears to support healthy liver. Population-based study[46] has shown that men who drink more than 10 cups of green tea per day are less likely to develop disorders of the liver. Animal studies[47] demonstrated that green tea helps to protect liver from the damaging effects of toxic substances such as alcohol.
20 Gastrointestinal tract effects
In the gastrointestinal tract, green tea was found to activate intracellular antioxidants and reduce inflammation. High green tea consumption (more than 10 cups per day) may prevent chronic atrophic gastritis[48]. Also, green tea may help reduce inflammation associated with Crohn's disease and ulcerative colitis, the two types of Inflammatory Bowel Disease (IBD).
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