A related compound found in tea is theophylline, which is a licensed medicine for the treatment of respiratory diseases such as asthma.
Tea also contains flavonoids, compounds reported to have anti-oxidant properties. These effects may be beneficial to health such as in the prevention of heart disease and cancer. Tea flavonoids are also reported to reduce inflammation and to have antimicrobial effects. Some studies suggest that tea may help prevent tooth decay. Consumption of tea may have diuretic effects, which is largely due to the caffeine, and tea may also inhibit the absorption of iron in the gut. Tea is also used in some cosmetic products for an astringent effect.
The possible beneficial health effects of tea consumption have been suggested and supported by some studies, but others have not found beneficial effects. One should consult a doctor before using high concentrations of tea for disease prevention. Ingestion of large amounts of tea may cause nutritional and other problems because of the strong binding activities of tea polyphenols and the caffeine content, although no solid data exist concerning harmful effects of tea consumption.