Eating walnuts may change gut bacteria in a manner that suppresses cancer of the colon, researchers led by UConn Health report in the journal Cancer Prevention Research.
A team of researchers from UConn Health insurance and The Jackson Laboratory for Genomic Medicine discovered that mice that ate 7-10.5 percent of their total calories as walnuts developed fewer colon cancers. The result was most pronounced in male mice, which had 2.three times fewer tumors when fed walnuts within a diet like the typical American’s. That’s equal to a human eating about an ounce of walnuts every day.
“Our results show for the very first time that walnut consumption may reduce colon tumor development,” said Principal Investigator Dr. Daniel W. Rosenberg of UConn Health. “You can find accumulating evidence that eating walnuts may give a variety of benefits related to medical issues like cancer. This study implies that walnuts may become a probiotic to help make the colon healthy also, which offers protection against colon tumors.”
Walnuts are filled with compounds regarded as important nutritionally. They may have the most polyunsaturated essential fatty acids of all commonly eaten tree nuts, as well as the best ratio of omega-3 to omega-6 essential fatty acids, and high degrees of a kind of Vitamin E with anti-cancer properties.
But walnuts aren’t the sum with their chemical parts merely, and it can be all together food that they pack the most important anti-cancer punch against cancer of the colon, the third most usual cancer in the global world. Other studies have shown walnuts have promise warding off diseases linked to lifestyle and diet, including cardiovascular disease, diabetes and neurological disorders.
Rosenberg, a cancer professor and researcher of medicine at UConn Health insurance and Dr. Masako Nakanishi, a study associate in the guts for Molecular Medicine at UConn Health tested the cancer prevention qualities of walnuts on mice fed two different diets. One band of mice ate a typical lab mouse chow, as the other group ate a chow that captured the nutritional profile of the normal American diet. Subsets of both combined groups were supplemented with walnuts.
Interestingly, male mice fed the Western diet fortified with 10.5 percent walnuts showed the best reduction in colon tumors weighed against mice fed no walnuts.
To determine why walnuts were beneficial, the UConn Health team collaborated with Dr. George colleagues and Weinstock with the Jackson Laboratory. Weinstock’s lab took fecal samples from the mice and analyzed the communities of bacteria moving into their digestive tracts. They discovered that walnut consumption tended to push the gut microbiome toward an ecology that was potentially protective against cancer. It isn’t clear just how this works, but there are clues. For instance, previous research shows that some gut bacteria digest fiber into compounds with anti-inflammatory properties which may reduce tumor initiation. The microbiome analyses also reflected interesting dissimilarities between male and female. Males on walnut-free diets tended to obtain less-diverse gut flora than females. Adding walnuts to the diets of male mice brought their microbiomes nearer to those of female mice on either of the diets. Whether this change plays a part in the protection observed in male mice remains to be determined.
As the studies were done only in mice, more testing must be achieved in humans before walnuts can be unequivocally recommended as a cancer-prevention agent. Rosenberg’s group is dealing with a nutritionist and surveying human colonoscopy patients about their diets within an extended term study in humans.
However, Rosenberg isn’t looking forward to the ultimate word. Right now even, he says, “I make an effort to eat walnuts every day.”
He adds: “We’re worked up about future studies where we are able to check out food consumption patterns to observe how these results connect with humans.”
This research was supported partly by the California Walnut Commission (CWC) and the American Institute for Cancer Research.
‘Tis the growing season to enjoy walnuts
M. Nakanishi et al, Ramifications of walnut consumption on colon carcinogenesis and microbial community structure, Cancer Prevention Research (2016). DOI: 10.1158/1940-6207.CAPR-16-0026