Camellia sinensis leaves are used to make black, oolong and green teas. Steaming the fresh leaves makes green tea, which is used medicinally for indigestion, energy and anticancer effects, among other reasons.

Green tea leaves have been studied to identify active, healthful compounds. According to the National Institutes of Health, tea leaves contain antioxidants and caffeine that may improve cell function and alertness.

Green tea leaves brewed as tea to drink or to dissolve into topical products or oral lozenges. They can also be ground into a powder to mix into other foods.

Green tea has been used since as early as 5,000 B.C. by the Chinese for its healing, revitalizing and digestive effects. However, research has not yet corroborated these green tea benefits.

Green tea may benefit digestion and nutrition by providing vitamins important to the body, such as vitamins B, C and E. The high antioxidant effect of green tea may be the reason for any digestive effects, because antioxidants help cells in the body function more efficiently and help clear waste.

Green tea contains polyphenols that provide the antioxidant effect against cancer development and poor digestion. All of these polyphenols also attack bacteria and viruses, such as those that may colonize the gastric system; epigallocatechin gallate is the strongest of the polyphenols in green tea, and it reduces swelling in the stomach to help digestion. B vitamins help the body absorb nutrients such as carbohydrates.

Green tea has many reported benefits, but few are research supported in controlled trials. However, caffeine is known to slow digestion and irritate the stomach with acidity. Because green tea does contain caffeine, it is possible that green tea may irritate the stomach in some people. In addition, acidic stomach contents used to digest foods may remove or inactive the beneficial anticancer effects green tea.