Green tea contains salubrious polyphenols, particularly catechins, the most abundant of which is epigallocatechin gallate. Green tea also contains carotenoids, tocopherols, ascorbic acid (vitamin C), minerals such as chromium, manganese, selenium or zinc, and certain phytochemical compounds. It is a more potent antioxidant than black tea,although black tea has substances which green tea does not such as theaflavin.
In vitro, animal, preliminary observational, and clinical human studies suggest that green tea can reduce the risk of cardiovascular disease, dental cavities, kidney stones, and cancer, while improving bone density and cognitive function. However, the human studies are inconsistent.
Green tea consumption is associated with reduced heart disease in epidemiological studies. Animal studies have found that it can reduce cholesterol. However, several small, brief human trials found that tea consumption did not reduce cholesterol in humans. In 2003 a randomized clinical trial found that a green tea extract with added theaflavin from black tea reduced cholesterol.
A study performed at Birmingham (UK) University, showed that average fat oxidation rates were 17% higher after ingestion of green tea extract than after ingestion of a placebo.[Similarly the contribution of fat oxidation to total energy expenditure was also significantly higher by a similar percentage following ingestion of green tea extract. This implies that ingestion of green tea extract can not only increase fat oxidation during moderately intensive exercise but also improve insulin sensitivity and glucose tolerance in healthy young men.
A recent study looked at the effects of short term green tea consumption on a group of students between the ages of 19–37. Participants were asked not to alter their diet and to drink 4 cups of green tea per day for 14 days. The results showed that short term consumption of commercial green tea reduces systolic and diastolic Blood Pressure, fasting total cholesterol, body fat and body weight. These results suggest a role for green tea in decreasing established potential cardiovascular risk factors. This study also suggests that reductions may be more pronounced in the overweight population where a significant proportion are obese and have a high risk of cardiovascular disease.
In a study performed at the Israel Institute of Technology, it was shown that the main antioxidant polyphenol of green tea extract, EGCG, when fed to mice induced with Parkinson's and Alzheimer's disease, helped to protect brain cells from dying, as well as 'rescuing' already damaged neurons in the brain, a phenomenon called neurorescue or neurorestoration. The findings of the study, led by Dr. Silvia Mandell, were presented at the Fourth International Scientific Symposium on Tea and Human Health in Washington D.C., in 2007. Resulting tests underway in China, under the auspices of the Michael J. Fox Foundation, are being held on early Parkinson's patients.
A study performed at the National institute of Chemistry in Ljubljana, Slovenia, demonstrated that EGCG from green tea inhibits an essential bacterial enzyme gyrase by binding to the ATP binding site of the B subunit. This activity probably contributes to the antimicrobial activity of green tea extract and may be responsible for the effectiveness of green tea in oral hygiene.
In a recent case-control study of the eating habits of 2,018 women, consumption of mushrooms and green tea was linked to a 90% lower occurrence of breast cancer.
A recent study on rats at the University of Hong Kong, published in the February issue of Journal of Agricultural and Food Chemistry, found that the catechins in green tea were absorbed by the lens, retina and other parts of the eye. The absorbed catechins reduced oxidative stress in the eye for up to 20 hours, suggesting that green tea may be effective in preventing glaucoma and other diseases of the eye.
In vitro, animal, preliminary observational, and clinical human studies suggest that green tea can reduce the risk of cardiovascular disease, dental cavities, kidney stones, and cancer, while improving bone density and cognitive function. However, the human studies are inconsistent.
Green tea consumption is associated with reduced heart disease in epidemiological studies. Animal studies have found that it can reduce cholesterol. However, several small, brief human trials found that tea consumption did not reduce cholesterol in humans. In 2003 a randomized clinical trial found that a green tea extract with added theaflavin from black tea reduced cholesterol.
A study performed at Birmingham (UK) University, showed that average fat oxidation rates were 17% higher after ingestion of green tea extract than after ingestion of a placebo.[Similarly the contribution of fat oxidation to total energy expenditure was also significantly higher by a similar percentage following ingestion of green tea extract. This implies that ingestion of green tea extract can not only increase fat oxidation during moderately intensive exercise but also improve insulin sensitivity and glucose tolerance in healthy young men.
A recent study looked at the effects of short term green tea consumption on a group of students between the ages of 19–37. Participants were asked not to alter their diet and to drink 4 cups of green tea per day for 14 days. The results showed that short term consumption of commercial green tea reduces systolic and diastolic Blood Pressure, fasting total cholesterol, body fat and body weight. These results suggest a role for green tea in decreasing established potential cardiovascular risk factors. This study also suggests that reductions may be more pronounced in the overweight population where a significant proportion are obese and have a high risk of cardiovascular disease.
In a study performed at the Israel Institute of Technology, it was shown that the main antioxidant polyphenol of green tea extract, EGCG, when fed to mice induced with Parkinson's and Alzheimer's disease, helped to protect brain cells from dying, as well as 'rescuing' already damaged neurons in the brain, a phenomenon called neurorescue or neurorestoration. The findings of the study, led by Dr. Silvia Mandell, were presented at the Fourth International Scientific Symposium on Tea and Human Health in Washington D.C., in 2007. Resulting tests underway in China, under the auspices of the Michael J. Fox Foundation, are being held on early Parkinson's patients.
A study performed at the National institute of Chemistry in Ljubljana, Slovenia, demonstrated that EGCG from green tea inhibits an essential bacterial enzyme gyrase by binding to the ATP binding site of the B subunit. This activity probably contributes to the antimicrobial activity of green tea extract and may be responsible for the effectiveness of green tea in oral hygiene.
In a recent case-control study of the eating habits of 2,018 women, consumption of mushrooms and green tea was linked to a 90% lower occurrence of breast cancer.
A recent study on rats at the University of Hong Kong, published in the February issue of Journal of Agricultural and Food Chemistry, found that the catechins in green tea were absorbed by the lens, retina and other parts of the eye. The absorbed catechins reduced oxidative stress in the eye for up to 20 hours, suggesting that green tea may be effective in preventing glaucoma and other diseases of the eye.
