Green tea seems to be the drink of the month — or even of the year. I’m receiving a lot of press releases about studies proclaiming its possible health benefits, particularly in preventing cancer.

One of the latest green-tea-and-cancer studies to cross my desk comes from Japan, where green tea is so ubiquitous that Coca-Cola now sells a green-tea-enhanced version of its cola. Researchers analyzed data from six different large Japanese studies and found an association between green tea drinking and a reduced risk for stomach (gastric) cancer — but only in women, not men.

In this meta-analysis, the women who experienced a significant decrease in stomach cancer risk drank five or more cups of green tea daily.

The study, which was published in Gut (yes, there is a medical journal with that name), had several limitations. Most important, the data was from observational studies that relied on the participants’ own recollections of how much tea they drank. Such studies can show only an association between two things, not a cause and effect. It could be that participants with stomach cancer cut back on their tea consumption before they were diagnosed due to early symptoms of the disease, which can include nausea, indigestion and heartburn.

The National Cancer Institute estimates that there will be about 21,000 new cases of stomach cancer diagnosed this year in the United States. Almost 11,000 people will die from the disease. Men are at a slightly greater risk than women of developing stomach cancer.

Before you run out and stock up on green tea, be aware that although this and other research on green tea and cancer is intriguing, results have so far been contradictory. Some studies, like this one, have found preventive benefits; others haven’t. In any case, no single food is going to improve your health — or, more to the point, ward off cancer.