The active compounds in green tea are polyphenols known as catechins. The most abundant polyphenol in green tea is epigallocatechin gallate, which may inhibit the action of the reactive oxygen species molecule, thereby preventing oxidative damage.
Varying amounts of green tea consumption were significantly associated with lower risks for cardiovascular disease, myocardial infarction, stroke, intracerebral hemorrhage, cerebral infarction, and elevated LDL levels. A plausible explanation for the preventive effects on cardiovascular disease involves the antioxidative and anti-inflammatory properties of green tea. Xiang and colleagues in a retrospective study showed that frequently drinking small amounts of green tea was associated with a reduced risk for coronary heart disease in women—but not in men.
Neurodegeneration and Cancer
Roy and Bhat found that green tea polyphenols suppress, disaggregate, and modulate γ-Synuclein fibrillation, which has an important potential role in Parkinson disease. Their research supports the possible beneficial effects of green tea against neurodegeneration, while demonstrating that EGCG-generated oligomers may reduce the viability of neuroblastoma cells but protect breast cancer cells from γ-Syn toxicity.
Schröder and colleagues found that epigallocatechin gallate and quercetin (in extracted forms and as found naturally in green tea) have anticarcinogenic effects on both estrogen receptor-positive and -negative breast cancer cells.
Yang and colleagues reported that green tea polysaccharides decreased microRNA-93—a potential therapeutic target for prostate cancer—and inhibited the growth of prostate cancer cells.
Wang and colleagues investigated the antioxidant effects of green tea polyphenols in preventing hyperuricemia, which leads to preglomerular arteriopathy and chronic kidney disease. They discovered that green tea polyphenols protect against the progression of chronic kidney disease by activating the Jagged1/Notch1-STAT3 pathway.
Whether the consumption of green tea has any true effect on the risk for kidney stones remains unanswered.
In prospective cohorts comprising 58,054 men and 69,166 women, Shu and colleagues found that drinking green tea was associated with a lower risk for self-reported incident kidney stones, an effect that was stronger in men.
In contrast, Wu and colleagues found that tea consumption was a risk factor for the development of kidney stones, although participants in their study drank a combination of green, black, and scented teas.
High levels of calcium oxalate in the urine are associated with a higher risk for kidney stone formation. Green tea contains much lower levels of oxalate and a higher concentration of epigallocatechin gallate, which acts to hinder the formation of kidney stones. (Black tea contains high levels of oxalate and has been shown to increase urinary oxalate concentrations when consumed regularly, prompting recommendations that black tea be eliminated from the diets of people who are prone to form kidney stones).
Other Potential Benefits of Green Tea
Periodontal disease prevention. Green tea promotes periodontal health by reducing inflammation, preventing bone resorption, and inhibiting the growth of certain bacteria associated with periodontal diseases. Gartenmann and colleagues, while noting the heterogeneous nature of the data, found that as an adjunct to scaling and root planing in periodontics, local application of green tea catechin may result in beneficial reduction of probing pocket depth. In addition to its systemic benefits, the discovery of the topical benefits of green tea has led to the marketing of green tea toothpaste.
Stress reduction. L-theanine—a major amino acid in matcha—has been shown to have stress-reducing effects. Matcha also contains an abundance of caffeine, which antagonizes the effects of L-theanine. Therefore, the relative concentrations of these and other components (epigallocatechin gallate and arginine) determine the effectiveness of matcha in stress reduction.
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Cite this: Drinking Tea: Are the Health Benefits Real? - Medscape - Jan 17, 2019.