Eating bananas can reduce cancer risk by over 60%

Lynch syndrome, a genetic condition caused by germline mutations in DNA mismatch repair genes, significantly increases cancer risk.

This syndrome affects one in 300 people, raising the lifetime risk of developing colorectal cancer to 80%, along with heightened risks for endometrial, ovarian, and other cancers. The challenge lies in finding effective prevention methods for this high-risk population.

A promising avenue is the role of dietary interventions, particularly resistant starch—a type of fermentable fiber—in reducing cancer risk. Found in foods like slightly green bananas, oats, and pulses, resistant starch passes undigested through the small intestine and ferments in the large bowel, nourishing beneficial gut bacteria.

This process produces short-chain fatty acids, including butyrate, which have anti-cancer properties. Additionally, resistant starch appears to modify the bacterial metabolism of bile acids, potentially lowering the production of DNA-damaging bile acid types.

The significance of resistant starch was highlighted in the CAPP2 trial, a groundbreaking study conducted by researchers from Newcastle and Leeds universities. Initiated in 1999, this trial involved nearly 1,000 individuals with Lynch syndrome.

Participants were assigned to receive 600 mg of aspirin, 30 grams of resistant starch, or placebos daily for two years in a double-blind design. The study’s primary goal was to assess whether these interventions could prevent colorectal cancer, with secondary outcomes focusing on non-colorectal cancers associated with Lynch syndrome.

Initially, results showed no significant difference in cancer incidence between groups. However, epidemiological evidence suggested that aspirin’s protective effects might emerge only after prolonged periods.

To address this, the trial incorporated a follow-up phase extending up to 20 years, supported by national cancer registries in England, Wales, and Finland. This long-term analysis revealed a striking result: while resistant starch did not significantly impact bowel cancer rates, it reduced the incidence of cancers in other parts of the body by more than 50%.

The protective effects were particularly pronounced for upper gastrointestinal (GI) cancers, including esophageal, stomach, biliary tract, and pancreatic cancers.

Among 463 participants who consumed resistant starch, only five cases of upper GI cancers were reported, compared to 21 cases in the 455 participants who received the placebo. This reduction—over 60% for these hard-to-diagnose and often fatal cancers—marks a significant advancement in cancer prevention for Lynch syndrome patients.

Professor John Mathers, a nutrition expert from Newcastle University, emphasized the importance of these findings. “We found that resistant starch reduces a range of cancers by over 60%. The effect was most obvious in the upper part of the gut. This is important as cancers of the upper GI tract are difficult to diagnose and often are not caught early on,” he noted.

Mathers also highlighted the need for further research to understand the exact mechanisms, particularly the role of bile acid metabolism.

The trial also reaffirmed the benefits of aspirin. Participants who consumed aspirin experienced a 50% reduction in large bowel cancer risk. This evidence influenced the National Institute for Health and Care Excellence (NICE) to recommend aspirin for individuals at high genetic risk of colorectal cancer.

However, resistant starch’s protective effects extended beyond aspirin’s scope, covering a broader range of cancers and demonstrating persistent benefits even a decade after supplementation ceased.

Resistant starch’s versatility adds to its appeal. It can be incorporated into the diet naturally through foods like peas, beans, and whole grains or consumed as a powdered supplement. Beyond its cancer-preventive properties, resistant starch provides fewer calories than regular starch, making it a health-conscious choice.

The findings from CAPP2 also underscore the broader health benefits of dietary fiber. Past studies have linked high fiber intake with reduced risks of colorectal cancer, cardiometabolic diseases, and all-cause mortality.

Fiber’s protective role is attributed to its complex composition, which includes carbohydrates that resist small-bowel digestion and undergo fermentation in the large bowel. The production of short-chain fatty acids and alterations in gut microbiota are key mechanisms underpinning these health benefits.

Despite these promising results, the researchers remain cautious. Professor Tim Bishop from the University of Leeds expressed optimism tempered with a call for replication. “The results are exciting, but the magnitude of the protective effect in the upper GI tract was unexpected, so further research is required to replicate these findings,” he stated.

This caution has led to the launch of the CaPP3 international trial, involving over 1,800 individuals with Lynch syndrome. This study aims to determine whether lower doses of aspirin can provide similar protective effects while minimizing potential side effects. As the scientific community builds on these findings, resistant starch emerges as a simple yet powerful tool in cancer prevention.

Funding for this groundbreaking research came from organizations including Cancer Research UK, the European Commission, the Medical Research Council, and the National Institute for Health Research. Their support underscores the global interest in addressing the unmet needs of Lynch syndrome patients and advancing cancer prevention strategies.

The implications of resistant starch extend beyond individuals with Lynch syndrome. Its potential as a cancer-preventive agent offers hope for broader populations, particularly those at high risk of upper GI cancers.

By integrating resistant starch into everyday diets, society can take a proactive step toward reducing the burden of cancer and improving public health outcomes.

Note: Materials provided above by The Brighter Side of News. Content may be edited for style and length.

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