New research supports and expands on previous studies to suggest that a lower risk of ovarian cancer may be as close as your teacup. Among a large group of Swedish women, those who drank at least two cups of tea a day developed 46 percent less ovarian cancer than non-tea drinkers.
Black tea, which is the most popular tea in the U.S., is what most of these tea drinkers consumed, rather than the green tea, which is more common among Asian populations.
This latest study linking tea with less ovarian cancer followed more than 61,000 Swedish middle-aged and older women for about 15 years. Those who drank at least two daily cups of tea had the lowest rates of this cancer, but even one cup a day decreased a woman’s risk by 24 percent.
Admittedly, tea-drinkers tend to have healthier lifestyles in many Western cultures than the general population because they exercise more, drink less alcohol, practice better weight control and eat more vegetables. In this study, however, other possible influences were taken into account. The lowered risk appeared after adjustments were made for factors influencing ovarian cancer risk, like a woman’s weight, age, past pregnancies and consumption of calories, fruits, vegetables and alcohol.
Since the study took place in Sweden, which is a nation of coffee drinkers, it’s important to note that coffee consumption was unrelated to risk. The benefits of tea weren’t due to drinking less coffee. Of course, some unidentified aspect of the tea drinkers’ lifestyle or diet could still be involved in the reduced cancer risk.
An earlier study compared women with ovarian cancer to a group of healthy women. Daily tea drinkers were 60 percent less likely to develop this type of cancer, and those who had drunk tea for more than thirty years had a more than 75 percent lower risk. Black or oolong tea seemed as protective as green tea, but since this study took place in China, more than 90 percent of the tea drinkers chose green tea.
The results did not make any adjustment for differences in vegetable consumption between tea drinkers and non-tea drinkers, but such an adjustment may be unnecessary for this population group. The researchers did account for differences in age, weight status, past pregnancies, exercise and alcohol consumption in their results.
Antioxidants repair cells
The ongoing Iowa Women’s Health Study of women past menopause shows a less clear relationship between tea and ovarian cancer. Although women who drank tea even once a week cut their rate of this cancer almost in half compared to non-tea drinkers after eight years, there was no effect to drinking more than a cup a day. Because relatively few women in this study developed ovarian cancer, the basis for any conclusion was further weakened.
Laboratory studies suggest that tea could protect against ovarian cancer, as well as other cancers, in several ways.
Some natural substances in tea are powerful antioxidants that seem to help prevent and repair damage to cells’ DNA that can lead to cancer. In addition to inhibiting the ability of carcinogens to begin the cancer process, these natural phytochemicals might work at later stages of cancer development, too, inhibiting the growth and spread of cancer cells and increasing their self-destruction. In one Chinese study, women with ovarian cancer who drank at least a cup of green tea daily were more than twice as likely to survive as non-tea drinkers.
As optimistic as these studies sound about the ability of tea to substantially reduce the impact of one particular cancer, the broad view of research indicates that a simple solution like tea is unlikely. Although the results of studies on ovarian cancer are rather inconsistent, several suggest that controlling your weight, limiting animal fat and eating plenty of dark green and other kinds of vegetables may also help guard you from this and other cancers.
Nutrition Notes is provided by the in Washington, D.C.© 2006 MSNBC Interactive