Colon cancer survivors can give their health a boost by eating more navy beans, a new clinical trial finds.

Small, white navy beans are full of gut-supporting fibers, amino acids and other nutrients that can help the beneficial bacteria of the gut flourish, researchers said.

And colon cancer patients who added a cup of navy beans to their regular meals saw positive changes in their gut microbiome, the collection of microbes that live inside the digestive tract.

These changes have been associated with preventing future cancers and improved treatment outcomes, the researchers said.

“Observing a shift in microbiome diversity with diet intervention alone is rare, and this study underscores the ability of a readily available prebiotic food to bring about such changes,” said researcher Carrie Daniel-MacDougall, an associate professor of epidemiology at the University of Texas MD Anderson Cancer Center.

“Over the course of eight weeks, there was an improvement in participants' gut health, marked by an increase in beneficial bacteria, which wards off the harmful bacteria,” Daniel-MacDougall added in a cancer center news release.

Obesity, poor diet and GI problems can cause a person’s normal microbial balance to become imbalanced. For colon cancer patients, these changes can cause inflammation that interferes with their treatment and can affect their survival.

For this study, researchers followed 48 obese men and women over 30 who had a history of cancer-related bowel problems. Three out of four had been diagnosed with colon cancer, and the rest had high-risk precancerous polyps found in their GI tract during colonscopy.

For eight weeks, participants were randomly assigned to eat either their regular diet or add a daily cup of cooked white navy beans.

Participants regularly provided stool and fasting blood samples, which allowed researchers to assess shifts in their gut microbiome and overall health.

Observed changes included an increase in beneficial bacteria and a decrease in potentially harmful bacteria, researchers report.

“The beans did not appear to induce gut inflammation or seriously impact bowel habits, which is crucial for... survivors and patients,” Daniel-MacDougall said. “However, once participants stopped eating the beans, the positive effects faded quickly, highlighting the need to educate patients on how to maintain healthy habits.” 

Daniel-MacDougall did caution that people should not add white navy beans to their diet without talking to their doctor first.

Future research is needed to figure out how a wider variety of such foods could help cancer patients, particularly those undergoing immunotherapy, she added.

The study, which was funded by the American Cancer Society, was published Nov. 30 in the journal eBIOMedicine.