Walnuts Could Potentially Prevent Colon Cancers

Male mice that ate 10.5% of their calories in walnuts had 2.3 times less tumors.

Findings from a new study suggest that walnuts could potentially prevent colon cancer by changing gut bacteria.

According to the study published in Cancer Prevention Research, mice that ate 7 to 10.5% of their daily calories in walnuts were less likely to develop colon cancers than mice that did not consume walnuts. Researchers found that male mice had 2.3 times less tumors when fed that amount of walnuts.

For humans, this would be approximately 1 ounce per day.

"Our results show for the first time that walnut consumption may reduce colon tumor development," said principal researcher Daniel W. Rosenberg, PhD. "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."

In the study, the mice were either fed standard lab mouse food or food that had the nutritional profile of the typical American diet, either with or without walnuts.

Male mice receiving the American diet with 10.5% walnuts had the most significant decrease in colon tumors compared with mice that did not get fed walnuts, according to the study.

Researchers then gathered fecal samples from the mice to analyze the bacteria in their digestive tracts and discovered that the mice that ate walnuts had a gut microbiome that was possibly protective against cancer.

Previous studies have suggested that gut bacteria digest fiber into compounds that have anti-inflammatory properties that could reduce the likelihood of tumor development.

In the current study, researchers noticed a significant difference in the gut flora between male and female mice, particularly in mice that did not consume walnuts. Male mice that did not consume walnuts had less varied gut flora than female mice.

However, male mice receiving walnuts had microbiomes similar to those of female mice on either diet, according to the study. More research needs to be conducted before walnuts can be recommended as an anti-cancer agent.

"We're excited about future studies where we will be able to look at food consumption patterns to see how these results apply to humans,” Dr Rosenberg concluded.