More Fiber, Less Fat Help Prevent Ovarian Cancer

The findings come on the heels of a similar study released by the same group in April. That study found that increased consumption of fruits and vegetables helps reduce the risk of head and neck cancers.

The same team has also shown that low-fat diets cut the odds of breast and colorectal cancers. Prior to the publication of this analysis, the impact of particular diets on ovarian cancer was unknown.

In the study, Prentice's team recruited almost 50,000 postmenopausal women between 50 and 79 years old. Almost 20,000 of those women were randomly assigned to eat a low-fat diet in which fat intake totaled less than 20 percent of daily calories. They also ate at least 5 servings of fruits and vegetables a day and at least 6 servings of whole grains.

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The women received 18 diet-support group sessions in the first year to help keep them on track and then quarterly maintenance meetings during the following years.

The researchers then monitored the women's rates of ovarian and/or endometrial malignancies over the next 8 years.

The result: Rates of ovarian cancer were roughly similar for women during the first 4 years of the study, whether they were enrolled on the low-fat diet or not. But by the end of more than 8 years of follow-up, a clear trend emerged, with women on the healthier diet having a 40 percent reduction in ovarian cancer incidence.

There was no such effect on the risk of endometrial cancer, however, the researchers added. That was surprising, Morgan said, because some experts theorize that fat increases estrogen levels in the body, which, in turn, may boost risk for both ovarian and endometrial cancer. Previous reports have indicated that low-fat diets lower circulating estrogen, said Morgan, so he expected to see a similar effect for both tumor types.

Women looking to duplicate the diet in their own lives should follow the Food Pyramid guidelines set out by the U.S. Department of Agriculture, Morgan said. But he added that one of the components that made this study so unique was the intense dietary counseling and support the women received over time.