Like black tea, green tea comes from the Camellia sinensis plant. The difference between them is green tea is made with unfermented leaves, while fully fermented leaves comprise black tea. Fermentation reduces the leaves' concentration of natural antioxidant compounds, or polyphenols, making green tea higher in antioxidants than black. The polyphenols in green tea appear to be more potent antioxidants than vitamin C, according to the University of Maryland Medical Center, and drinking it in moderation may benefit your health.
Catechins
Green tea contains six different types of polyphenols from the catechin family. The most active and widely studied of these is epigallocatechin gallate, or EGCG, a powerful antioxidant compound that also has antibacterial properties, according to authors of a "British Journal of Pharmacology" article published in 2013. They also noted that drinking green tea may ward off viral infections, such as influenza, hepatitis and herpes simplex, and may offer antifungal and antibacterial benefits, preventing a wide variety of diseases.
Cardiovascular Benefits
A high dose of antioxidants prevents free radicals from damaging your cells, protecting you from illness and premature aging. Drinking green tea may help keep your blood sugar and cholesterol low, making it a beneficial beverage for diabetics and people at an elevated risk for heart disease. It also may prevent atherosclerosis, or hardened arteries, according to Brazilian researchers who published a study in "Nutrition Research" in 2012. The research team found mice that drank water infused with a low dose of green tea extract for four weeks experienced significant improvements in atherosclerotic lesions and vascular reactivity, compared to mice that drank plain water. Higher concentrations of green tea extract were less effective than lower concentrations.
Cancer Prevention
In countries where green tea consumption is high, cancer rates tend to be low. Although research has yielded mixed results, some studies have indicated a link between green tea and a reduced risk of some types of cancer. Researchers from a study published in "Biomedical Research" in 2009 treated bladder cancer cells with green tea extract and found its catechin agents significantly inhibited the cells from growing. Green tea also may treat and prevent cancers of the pancreas, skin, breast, stomach, ovaries, esophagus, lungs and prostate.
Daily Intake
The potency of green tea varies from brand to brand, as does the potential for toxicity from excessive use. An overdose of green tea can lead to liver damage and other unpleasant side effects. To maximize the health benefits of green tea safely, the UMMC recommends drinking 2 to 3 cups daily, giving you 240 to 320 milligrams of polyphenols. If you take green tea extract supplements, 100 to 750 milligrams per day is recommended. Opt for caffeine-free products when possible. Because few studies have been done on green tea's effects on children, it is safest not to give it to them.
Source: http://healthyeating.sfgate.com/green-tea-good-much-can-drink-daily-8620.html
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