Green tea extract is derived from leaves of camellia sinensis, the plant from which green, black and oolong teas are made. Green tea extract is associated with several health benefits, many supported by preliminary scientific research. These benefits include potential cancer-fighting properties, and a strong antioxidant effect that protects the body from the damaging effect of free radicals. The scientific community notes, however, that continued research is necessary.

Green tea has been used for medicinal purposes in India and China for nearly 5,000 years. It is made by lightly steaming leaves of the plant before allowing them to dry. This process retains active properties of the plant. Oolong tea is made by allowing the leaves to ferment slightly before drying, and black tea is made by allowing the leaves to ferment longer. Fermentation breaks down the active ingredients, making green tea or green tea extract the tea of choice.

Green tea extract, like many herbs, is standardized in the production phase to guarantee that a certain percentage of the active ingredients remain present in the final capsulized form. The active ingredients in green tea extract are polyphenols in the form of flavinoids like catechins and epigallocatechin gallate (EGCG). Polyphenols, flavinoids, catechins and EGCG are powerful antioxidants that appear to interfere with and reduce the spread of certain types of cancer cells. The antioxidant activity of EGCG in green tea extract is purportedly up to 100 times more powerful than that of vitamin C or E.

Green tea extract might also be beneficial in improving cardiovascular circulation by reducing LDL or “bad cholesterol,” suppressing appetite and improving oxidation of fat. However, these claims are not widely accepted by the scientific community because they are based on animal models, and only a few human studies.