Tea is the most popular beverage in the world, and for an increasing number of Americans, green tea is the tea of choice. This crisp, astringent beverage is lauded for its health effects. It can be beneficial in preventing certain diseases of the liver, but as the adage states, too much of a good thing can hurt you. In high dosages, green tea can have a toxic effect on the liver.
Green vs. Black Tea
Green tea has such a different flavor and appearance than black tea that you might assume it's a whole different substance. As a matter of fact, both types of tea, and oolong too, are made from the leaves of the Camellia sinensis plant. The difference lies in the way the tea leaves are processed. Black tea undergoes a process called fermentation, wherein the leaves are rolled and crushed, breaking up their fibers and releasing enzymes that oxidize substances within them called polyphenols. Oolong tea is also fermented, but not as thoroughly as black tea. Green tea is not fermented, thus leaving its polyphenols intact. This is good from a health perspective, because polyphenols are powerful antioxidants, according to New York University's Langone Medical Center.
Green Tea Liver Benefits
A systematic review published in the journal "Liver International" studied the results of research conducted between 1989 and 2007 that focused on the effects of green tea on liver diseases. These studies examined such conditions as liver cancer, cirrhosis and fatty liver disease. The review found that eight of these studies indicated that green tea has significant protective effects against liver disease, and four of the studies indicated that green tea helped weaken the intensity of already existing liver disease.
Green Tea Liver Risks
On the other hand, too much green tea can hurt your liver more than help it. The "European Journal of Clinical Pharmacology" reviewed the literature concerning liver toxicity and green tea consumption and found that green tea extract has been associated with a number of cases of hepatotoxicity, or liver toxicity.
Considerations
Evidence indicates that epigallocatechin gallate, the same polyphenol thought to be behind many of green tea's positive effects, may also be the culprit in cases of liver toxicity. Drinking green tea in moderation is unlikely to harm you, but you should not take green tea extracts or supplements without consulting a doctor, due to the possibility of liver toxicity.
References
- "Liver International"; Green Tea Consumption and Liver Disease: A Systematic Review; Xi Jin, et al.; May 2008
- "European Journal of Clinical Pharmacology"; Hepatotoxicity From Green Tea: A Review Of The Literature And Two Unpublished Cases; Gabriela Mazzanti, et al.; February 2009
- New York University Langone Medical Center; Green Tea; 2011
