In sharp contradiction to past medical research, a 14-year study of 88,795 women bore no evidence that a low-fat diet protects against breast cancer or that a high-fat diet increases women’s risk for breast cancer.
Medical experts have long hypothesized that a high-fat diet may increase a woman’s risk for cancer. This hypothesis was based largely on animal research and research that compared the diets of women living in different regions in the world. Many have hypothesized that animal fats and saturated fats are the culprits, while other fats, such as the fat found in fish oil, can actually protect against cancer.
The study published today in the Journal of the American Medical Association calls all of these past hypotheses into question. Researchers used data from the ongoing Nurses’ Health Study to test these hypotheses among a sample of nearly 89,000 women. All of these women were between 30 and 55 years old and were cancer-free at the time they entered the study. Beginning in 1980 and ending in 1994, these women completed a detailed survey about the foods they ate once every four years.
Using this data, researchers compared the eating habits of women who were cancer free to the eating habits of women who developed breast cancer during the study. They found that women who ate a high-fat diet or who ate large proportions of animal fat, polyunsaturated fat (vegetable fat), or trans-unsaturated fat (partially-hydrogenated oils) were no more likely than women who followed a low-fat diet, or who avoided these particular types of fats.
Researchers stressed that, although this study questions the link between high dietary fat and breast cancer, women should still strive to maintain a high fiber, low-fat diet. High dietary fat has been linked to many other health problems, including heart disease.