A study spanning more than 20 years and nearly 1,000 participants worldwide found a major finding: People with a condition that gives them a greater chance of developing certain cancers can reduce their risk of some of these cancers by more than 60%, simply by adding more resistant starch to their diet.
In fact, the results were so compelling when it came to reducing the risk of upper gastrointestinal (GI) cancers in particular that researchers are now trying to replicate them to make sure nothing is missing.
“We found that resistant starch reduced a range of cancers by more than 60 percent. The effect was most noticeable in the upper intestine,” says lead researcher and nutritionist John Mathers of Newcastle University in the UK.
Upper gastrointestinal cancers include esophageal, gastric, and pancreatic cancers.
“The results are exciting, but the extent of the protective effect in the upper gastrointestinal tract was unexpected, so more research is needed to replicate these findings,” adds one of the researchers, Tim Bishop, a genetic epidemiologist at the University of Leeds.
Resistant starch is a type of starch that passes through the small intestine and then ferments in the large intestine, where it feeds beneficial gut bacteria. It can be purchased as a fibrous supplement and is naturally present in a wide range of foods, including lightly green bananas, oats, cooked and cooled pasta and rice, peas and beans.
The double-blind study was conducted between 1999 and 2005 and involved a group of 918 people with a condition known as Lynch syndrome. Lynch syndrome is one of the most common genetic predispositions to cancer that we know of, with around one in 300 people estimated to carry an associated gene.
Those who have inherited the Lynch syndrome genes have a significantly higher risk of developing colorectal cancer, as well as gastric, endometrial, ovarian, pancreatic, prostate, urinary tract, kidney, bile duct, lung cancers. small intestine and brain.
To figure out how to reduce this risk, participants were randomly assigned to one of two groups, with 463 people unknowingly receiving a daily dose of 30 grams of powdered resistant starch for two years, roughly the equivalent of eat a not ripe enough. banana every day.
Another 455 people with Lynch syndrome took a daily placebo that looked like powdered starch but contained no active ingredients.
The two groups were then followed up 10 years later. The results of this follow-up are what the researchers have just published.
In the follow-up period, there were only 5 new cases of upper gastrointestinal (GI) cancers among the 463 people who took resistant starch. This is in comparison to 21 cases of upper gastrointestinal cancer among the 455 people in the placebo group – a pretty noticeable reduction.
“This is important as upper gastrointestinal cancers are difficult to diagnose and often go undetected,” says Mathers.
However, there was one area where resistant starch didn’t make much of a difference: in the rate of intestinal cancers.
More work is needed to understand exactly what’s going on here, but the team has some ideas.
“We think resistant starch can reduce cancer development by modifying bacterial metabolism of bile acids and to reduce those types of bile acids that can damage our DNA and eventually cause cancer,” says Mathers.
“However, this needs more research.”
To be clear, this study was conducted on people already genetically predisposed to developing cancer and does not necessarily apply to the wider public. But there could be a lot to learn from a better understanding of how resistive starch can help protect against cancer.
The original study was called the CAPP2 study, and the team is now doing a follow-up called CaPP3, which involves more than 1,800 people with Lynch syndrome.
While it may seem worrying that colorectal cancer rates were not affected by resistive starch, don’t worry, the study had good news on that front as well.
The original study also looked at whether daily aspirin intake could reduce cancer risk. In 2020, the team published results showing that aspirin reduced the risk of large bowel cancers in Lynch syndrome patients by 50%.
“Patients with Lynch syndrome are at high risk as they are more likely to develop cancers, so finding that aspirin can cut the risk of large bowel cancers in half and starch resistant to other cancers,” says the geneticist. of Newcastle University Sir John Burns who handled the trial with Mathers.
“Based on our process, NICE [the UK’s National Institute for Health and Care Excellence] now we recommend aspirin for people with a high genetic risk of cancer, the benefits are obvious: aspirin and resistant starch. “
The research was published in Cancer Prevention Research.