(Relaxnews) -

Drinking five cups of green tea a day could help women reduce the risk of developing stomach cancer by 20 percent, Japanese researchers say.

Green tea is made from unfermented leaves and has the highest concentration of a key antioxidant polyphenol -- a catechin called EGCG (epigallocatechin-3-gallate) -- that could fight the bacteria linked to stomach cancer, experts say. Antioxidants scavenge free radicals, damaging compounds in the body that can alter cells, cause cell death and change DNA.

In a pooled study of over 219,000 men and women over the age of 40, the researchers found over a long-term period that about four in five of the participants drank green tea daily. One third of those -- notably women -- who drank five or more cups a day revealed a decreased risk of developing gastric cancer, they found.

There is a great deal of documented evidence of the health benefits of drinking green tea. The EGCG polyphenol is believed to be responsible for most of the health benefits linked to green tea.

In addition to protecting against many forms of cancer, some of green tea's other well-known health properties include: lowering cholesterol, improving the ratio of "good" cholesterol to "bad" cholesterol, controlling blood sugar, preventing infection, and sometimes treating cardiovascular disease.

More recent research has shown that green tea can strengthen bones, prevent tooth decay and help with weight loss because of its calorie-burning properties.

But green tea also contains caffeine, so it might not help with insomnia, but it does contain less caffeine than coffee per cup, health experts say.

The researchers published their findings online in June in Gut: An International Journal of Gastroenterology and Hepetology ahead of print.