The study, which appears Tuesday in the current issue of the Journal of the National Cancer Institute, analyzed 40,000 older women over an average of eight years.
Results revealed that those who ate a low-fat diet consisting of more whole grains, fruits and vegetables showed a lower risk of developing ovarian cancer in the last four years of the study.
Low-fat diet cut a women's chance of ovarian cancer by 40 percent, the study said.
Lead author Ross Prentice, interim director of the public health sciences division of the Fred Hutchinson Cancer Research Center in Seattle said, "The women whose intake is comparatively high in fat content -- 35 percent of calories from fat -- and who make the biggest reduction in fat content in their diet exemplify the strongest reduction in ovarian cancer risk."
The findings could potentially benefit thousands of postmenopausal women who are planning to prevent this deadly cancer.
However, the results also revealed that the diet made little impact on rates of breast cancer, colorectal cancer and heart disease partly because many women started healthier eating too late.
Ovarian cancer affects one in 60 women compared with the one in 9 who will get breast cancer. It is usually is detected only after it has spread throughout the abdomen, making it much harder to treat. Only 45 percent of patients survive five years.
The American Cancer Society estimates that 22,430 U.S. women will be diagnosed with ovarian cancer this year; 15,280 women will die of it.
Since the fat intake increases the amount of estrogen circulating in the blood, which may in turn overstimulate sensitive ovaries, the high fat diet can put extra pressure on ovaries.
Low-fat diet participants experienced a 15 percent reduction in estradiol, a key form of estrogen, while non-dieters experienced no change, the study authors said.
