Tea is a drink with wide ranging health benefits. Much has been written about the ability of tea to protect from cancer. Epidemiological studies show that tea is inversely associated with cancer, such that the more tea people drink, the lower their cancer risk. Animal studies also show cancer protective effect for tea. Many cell culture experiments confirm that tea is damaging to cancer cells. In act tea is probably the most researched food when it comes to cancer protection.
Not All Tea Is the Same
The benefits of tea are thought to stem from its polyphenol content. In particular, tea is a rich source of a group of polyphenols called catechins. Some or all of these catechins may possess anti-cancer effects in humans. However, only green tea is a rich source of catechins. Black tea does not contain the same high concentrations. This explains the better cancer protection afforded from drinking green tea in comparison to black tea.
When reviewing the literature regarding tea and cancer, it becomes clear that tea is particularly protective of cancers of the gut. This is interesting because it gives clues as to the mechanism by which tea might be effective against cancer. Cancer of the gut can develop from consumption of nitrites and nitrates in meat, that react in the gut and form carcinogenic nitrosamine compounds. When these interact with tissues in the gut they can initiate cancer.
Tea And Gut Cancer
Tea might be particularly effective against gut cancers because it inhibits the conversion of nitrate and nitrites to carcinogenic nitrosamine compounds. Vitamin C is a water soluble antioxidant, and is known to be able to inhibit this conversion. The catechins in green tea may therefore have similar effects as they are also powerful antioxidants like vitamin C. Green tea may therefore protect from cancer without needing to be absorbed into the body.
Red Wine and The Gut
The theory that green tea is beneficial at preventing cancer of the gut is supported by studies investigating red wine. As evidence about red wine accumulates it is becoming clear that it may have beneficial health effect in part because it inhibits the formation of lipid peroxides in the gut. This then lowers the risk of absorbing possibly dangerous chemicals and lowers the risk of initiating disease, particularly cancer and cardiovascular disease.
Best Way To Drink Tea
If the catechins in tea protect from cancer because of their presence in the gut, it makes sense to make sure the catechins are are present in the gut at times that carcinogens are likely to be formed. This means drinking green tea with meals, as is the tradition in Japan. As mentioned above, green tea contains more catechins than black tea and so green tea is preferable. However, even black tea offers some protection, so if green tea is not available, drink black tea with food instead.