Green tea has been used by the Chinese and traditional Chinese medicine to treat anything from aches and pains, headaches, poor digestion and to help an individual improve their overall well-being and life expectancy. Green tea extract is rich in bioflavonoids which are antioxidants. These antioxidants have a role of fighting free radicals within the body which cause DNA and cell damage. Some sources say that it is over 200 times more potent than vitamin E in fighting these free radicals.
Green tea is made from the dried leaves of the Camellia sinensis, a perennial evergreen shrub. There are several varieties of tea which grow in different regions and districts of China and India. Historically this tea has also been served as part of a variety of ceremonies and has been used to stay alert during long meditations.
Many manufacturers use green tea extract as a common ingredient in products which are designed to burn fat in the human body. It is believed to help with thermogenesis, which means it helps to raise the metabolism and work off fat. Many products which are used to help burn fat in the body will also raise the heart rate but green tea does not. Others use green tea extract as a weight-loss supplement and still others believe it helps to reduce the risk of heart attack, cancer and prevent liver failure.
There been several studies related to the use of green tea supplementation and extracts for its antioxidant qualities as well as its weight loss effects. Because green tea extract can stain the skin it makes it impractical for skin care formulations in order to decrease the effects of sun. In a recent study from Stanford University in California, in collaboration with a cosmetics company, researchers looked at the effects of using an oral preparation of green tea supplementation in order to decrease the characteristics that are associated with UV aging. (1)
According to the study, and a number of animal studies, which suggested that green tea supplements would stimulate regeneration and the aim of this particular study was to investigate the long-term effects. The study included 56 women who were asked to take one capsule twice a day for two years after which an assessment of the skin was performed at six-month intervals by a dermatologist on the subjects themselves.
After two years of supplementation with the green tea researchers found that there were no statistically significant differences in the individuals who used the green tea versus those who didn’t.
Although the specific benefits and doses of green tea have not been established most studies examine green tea in the form of a brewed beverage rather than in capsule form. One cup of brewed tea contains approximately 50 mg of caffeine and 80 to 100 mg of polyphenol content. In capsule form, there is a considerable variation in the amount of extract which may include between 100 and 750 mg per capsule. At this time there is no current medically established recommended dose for green tea extract capsules. However, it is not recommended for infants or children because of the caffeine content.
People who have unknown allergy or hypersensitivity to caffeine or tannin should avoid drinking green tea or using green tea extract. Side effects can include an increase in blood sugar levels, increased urine production, increased stomach acid, constipation, increased heart rate and blood pressure, caffeine toxicity (depending upon the amount taken), a potential for iron deficiency and decreased levels of estrogen in the body and some limited research which points to the possible relationship between caffeine and multiple sclerosis or worsening fibrocystic breast disease.
Unfortunately, for as many studies done which show that green tea extract has little to no benefit in certain aspects of health, there are others which show improved positive benefits. The majority of side effects seem to come from the caffeine content in the green tea extract and not from the extract itself. Using a green tea extract supplement to assist in weight-loss, decreased pain or lower cholesterol is a personal choice which must be made with the advice of your primary care physician. Because of the caffeine content which may interfere with other medications you are already taking, you should consult with both your primary care physician and your pharmacist regarding over the counter drugs, supplementation, vitamins and minerals and prescription medications.
References:
(1) Stanford University: A Double-Blinded, Placebo Controlled Trial to Determine the Role of a Combination Regimen of a Systemic and Topical Green Tea in UV Protection
http://www.nuskin.com/global/library/pdf/tfessence_greentea_clinical.pdf
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