Cancer prevention: Green bananas reduce cancer risk by more than 60%

A groundbreaking study has shown that resistant starch, found in everyday foods like oats and slightly green bananas, can significantly reduce the risk of various cancers. This discovery comes from the CAPP2 trial, which involved nearly 1,000 participants with Lynch syndrome from around the world. Leading this research were experts from the Universities of Newcastle and Leeds.

Lynch syndrome, affecting approximately one in 300 people in the UK, is a genetic condition that significantly raises the risk of developing cancers, particularly in the bowel, womb, and ovaries. Those with this syndrome have up to an 80% chance of developing bowel cancer in their lifetime and are also more likely to face other cancers at an earlier age compared to the general population.

The study’s results revealed that a regular dose of resistant starch, also known as fermentable fiber, taken for about two years, didn’t impact bowel cancer rates. However, it did reduce the incidence of cancers in other parts of the body by more than half.

This effect was especially strong for upper gastrointestinal (GI) cancers, such as those affecting the esophagus, stomach, biliary tract, pancreas, and duodenum. Remarkably, the protective effects of the starch persisted for up to 10 years after participants stopped taking the supplement.

Published in the journal Cancer Prevention Research, this study was meticulously planned as a double-blind trial, featuring a 10-year follow-up, with additional data from national cancer registries extending up to 20 years for 369 participants.

Resistant starch is a type of carbohydrate that bypasses digestion in the small intestine and ferments in the large intestine, where it nourishes beneficial gut bacteria. It functions similarly to dietary fiber in the digestive system and offers several health benefits, including fewer calories than regular starch.

Professor John Mathers, a leading nutrition expert from Newcastle University, suggests that resistant starch may reduce cancer development by altering the bacterial metabolism of bile acids.

“We think that resistant starch may reduce cancer development by changing the bacterial metabolism of bile acids and reducing those types of bile acids that can damage our DNA and eventually cause cancer,” he explained. However, he noted that more research is needed to fully understand this process.

Professor Mathers also highlighted the significant reduction in cancer risk associated with resistant starch, stating, "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."

The trial also found that aspirin reduced the risk of large bowel cancer by 50%, a discovery that led the National Institute for Health and Care Excellence (NICE) to recommend aspirin for individuals at high genetic risk of cancer.

Between 1999 and 2005, nearly 1,000 participants with Lynch syndrome began taking either resistant starch in powder form daily for two years, aspirin, or a placebo. At the end of the treatment phase, there was no immediate difference between those who had taken resistant starch or aspirin and those who had not. However, the research team anticipated longer-term effects and designed the study for extended follow-up.

During the follow-up period, only five new cases of upper GI cancers were reported among the 463 participants who had taken resistant starch, compared to 21 cases among the 455 who received the placebo. These findings underscore the potential of resistant starch as a protective agent against certain cancers.

Professor Tim Bishop from the University of Leeds, who was also involved in the trial, expressed both excitement and caution, stating, “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.”

Resistant starch can be consumed naturally through foods like peas, beans, and oats, or as a powdered supplement. Professor Mathers emphasized its health benefits, noting its lower calorie content compared to regular starch and its potential role in cancer prevention through modifying bile acid metabolism. However, he reiterated the need for further studies to confirm these benefits.

Looking ahead, the research team is leading the CaPP3 international trial, which involves over 1,800 people with Lynch syndrome. This new trial aims to determine whether smaller, safer doses of aspirin can effectively reduce cancer risk.

This groundbreaking research has been funded by Cancer Research UK, the European Commission, the Medical Research Council, and the National Institute for Health Research, highlighting its significance and the global interest in its findings.

The potential of resistant starch to serve as a simple, natural tool in cancer prevention opens new avenues for research and offers hope for those at high risk of developing cancer.

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

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