Eating walnuts may change gut bacteria in a way that supresses colon cancer, say researchers from UConn Health and The Jackson Laboratory for Genomic Medicine. They found that mice that ate 7 to 10.5 percent of their total calories as walnuts developed fewer colon cancers. The effect was most pronounced in male mice, which had 2.3 times fewer tumors when fed walnuts as part of a diet similar to a typical American’s. That’s equivalent to a human eating about an ounce of walnuts a day.
Walnuts are packed with compounds known to be important nutritionally. They have the most polyunsaturated fatty acids of all the commonly eaten tree nuts, as well as the highest ratio of omega-3 to omega-6 fatty acids, and high levels of a form of Vitamin E with anti-cancer properties. But walnuts are not merely the sum of their chemical parts, and it may be as a whole food that they pack the most significant punch against colon cancer, the third most common cancer in the world.
“There is accumulating evidence that eating walnuts may offer a variety of benefits related to health issues like cancer. This study shows that walnuts may also act as a probiotic to make the colon healthy, which in turn offers protection against colon tumors,” says Daniel W. Rosenberg, professor of medicine at UConn Health’s Center for Molecular Medicine and principal investigator on the study.
Testing needs to be done in humans before walnuts can be unequivocally recommended as a cancer-prevention agent. Rosenberg’s group is working with a nutritionist and surveying human colonoscopy patients about their diets as part of a longer term study in humans. However, Rosenberg isn’t waiting for the final word. “Even now,” he says, “I try to eat walnuts every day.” —kim krieger
This research was supported in part by the California Walnut Commission and the American Institute for Cancer Research.