This article is from the May/June 1991 AFRMA Rat & Mouse Tales news-magazine.

Research has found that eating foods high in fiber may help protect against breast cancer. The laboratory rats used in the research were fed high-fiber diets and developed fewer breast tumors than ones who received little or no fiber. The researchers found that by doubling the amount of fiber in a diet (similar to Western diets), you can significantly reduce the amount of mammary cancer, down to the level of a low-fat diet. The research showed that the fiber itself contains substances which, when it gets into the blood stream, will inhibit the formation of a mammary tumor. The way fiber might work against breast cancer seemed to differ between rats and humans, but the findings “suggest” that dietary fiber may function as an antipromoting agent in human breast cancer.

The research team used four groups of 30 rats each and gave them injections of a drug that causes breast cancer. Three days later, the groups of research rats were started on four diets with different levels of fat and fiber. One group got a high-fat diet and no fiber; another got a high-fat diet with fiber; a third got a low fat and low fiber diet; while the fourth got low fat and high fiber. (They used corn oil for the fat and white wheat bran for the fiber.) Fifteen weeks after the study began, 90% of the rats on the high-fat diets without the fiber supplement were found to have developed breast cancer, compared with 66% of those on high-fat, high-fiber diets. Sixty three percent of the rats on low-fat diets without fiber supplements had tumors compared with 47% for those on low-fat, high-fiber diets. Many studies have indicated that high-fat diets, such as those of many Americans, tend to promote breast cancer.