Resistant starch has been shown to have an important preventive effect on a wide range of cancers in people with a high hereditary risk.
Could a banana a day keep the doctor away from cancer?
An important preventive effect of resistant starch on a wide range of cancers has been shown in a trial in people with a high hereditary risk. Resistant starch can be found in a wide variety of foods such as oats, breakfast cereals, cooked and cooled pasta or rice, peas and beans, and slightly green bananas.
An international trial found that a regular dose of resistant starch, also known as fermentable fibre, taken for an average of two years did not affect bowel cancers, but did reduce cancers in other parts of the body more than half. This effect was particularly pronounced for upper gastrointestinal cancers, including esophageal, gastric, bile duct, pancreatic, and duodenal cancers. The trial, known as CAPP2, involved almost 1,000 Lynch syndrome patients from around the world.
Furthermore, the amazing effect was seen to last 10 years after the supplement was stopped.
The study is a planned 10-year double-blind follow-up, supplemented by complete data from the national cancer registry for up to 20 years in 369 of the participants. The research was led by experts from the Universities of Newcastle and Leeds and published on July 25, 2022 in Cancer Prevention Research, a journal of the American Association for Cancer Research.
Previous research published as part of the same trial revealed that aspirin reduced colon cancer by 50%.
“We found that resistant starch reduced a number of cancers by more than 60%. The effect was most evident in the upper part of the gut,” explained Professor John Mathers, professor of human nutrition at the University of Newcastle. “This is important as cancers of the upper gastrointestinal tract are difficult to diagnose and often go undetected at first.
“Resistant starch can be taken as a powdered supplement and is found naturally in peas, beans, oats and other starchy foods. The dose used in the trial is equivalent to eating a banana a day; before they are too ripe and soft, the starch in bananas resists decomposition and reaches the intestine where it can change the type of bacteria that live there.
“Resistant starch is a type of carbohydrate that is not digested in the small intestine, but instead ferments in the large intestine, feeding beneficial gut bacteria; it acts, in effect, like dietary fiber in the digestive system. This type of starch has several health benefits and fewer calories than regular starch. We believe that resistant starch can reduce the development of cancer by changing the bacterial metabolism of bile acids and reduce those types of bile acids that can damage our DNA and , ultimately causing cancer. However, this needs further research.”
Professor Sir John Burn, from Newcastle University and Newcastle Hospitals NHS Foundation Trust who led the trial with Professor Mathers, said: “When we started the studies more than 20 years ago, we thought that people with a predisposition genetics in colon cancer could help us test whether we could reduce the risk of cancer with aspirin or resistant starch.
“Patients with Lynch syndrome are at high risk because they are more likely to develop cancers, so the finding that aspirin can halve the risk of colon cancer and other resistant starch cancers is vital importance
“Based on our trial, NICE now recommends aspirin for people at high genetic risk of cancer, the benefits are clear: aspirin and resistant starch.”
Long term study
Nearly 1,000 participants between 1999 and 2005 began taking powdered resistant starch every day for two years, or aspirin or a placebo.
At the end of the treatment stage, there was no overall difference between those who had taken resistant starch or aspirin and those who had not. However, the research team anticipated a long-term effect and designed the study for further follow-up.
There were only 5 new cases of upper gastrointestinal cancers among the 463 participants who had taken the resistant starch, compared with 21 of the 455 who received placebo during the follow-up period.
The team is now leading the international trial, CaPP3, with more than 1,800 people with Lynch syndrome enrolled to test whether smaller, safer doses of aspirin can be used to help reduce cancer risk.
Reference: “Cancer prevention with resistant starch in patients with Lynch syndrome in the CAPP2 randomized placebo-controlled trial: planned 10-year follow-up” by John C. Mathers, Faye Elliott, Finlay Macrae, Jukka-Pekka Mecklin, Gabriela Möslein Fiona E. McRonald, Lucio Bertario, D. Gareth Evans, Anne-Marie Gerdes, Judy WC Ho, Annika Lindblom, Patrick J. Morrison, Jem Rashbass, Raj S. Ramesar, Toni T. Seppälä, Huw JW Thomas, Harsh J. Sheth, Kirsi Pylvänäinen, Lynn Reed, Gillian M. Borthwick, D. Timothy Bishop, and John Burn on behalf of the CAPP2 Investigators, 25 July 2022, Cancer Prevention Research.DOI: 10.1158/1940-6207.CAPR-22-0044
The research is funded by Cancer Research UK, the European Commission, the Medical Research Council and the National Institute for Health Research.