A study spanning more than 20 years and nearly 1,000 participants worldwide has found an important finding: People with a condition that puts them at greater risk of developing certain cancers may have a greater than 60 percent risk of some of those cancers. percent 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) cancer that the researchers are now trying to replicate them to make sure they don’t miss anything.
“We found that resistant starch reduces a range of cancers by more than 60 percent. The effect was most evident in the upper gut,” said lead researcher and nutritionist John Mathers of Newcastle University in the UK.
Upper GI cancers include esophageal, stomach, and pancreatic cancer.
“The results are exciting, but the magnitude of the protective effect in the upper GI tract was unexpected, so further research is needed to replicate these findings,” added one of the researchers, Tim Bishop, a genetic epidemiologist at the U.S. 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 nourishes beneficial gut bacteria. It can be purchased as a fibrous supplement and is found naturally in a range of foods, including light green bananas, oats, cooked and refrigerated pasta, and rice, peas and beans.
The double-blind trial 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 known, with an estimated one in 300 people having an associated gene.
Those who have inherited Lynch syndrome genes have a significantly increased risk of developing colorectal cancer, as well as stomach, endometrial, ovarian, pancreatic, prostate, urinary tract, kidney, bile duct, small bowel, and brain cancers .
To find out how to reduce this risk, participants were randomly assigned to one of two groups, with 463 unknowingly given 30 grams of powdered resistant starch every day for two years — roughly the equivalent of eating a not quite ripe banana. daily.
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 just published.
In the follow-up period, there were only 5 new cases of cancer of the upper gastrointestinal (GI) tract among the 463 people who had ingested the resistant starch. This compares with 21 cases of cancer of the upper gastrointestinal tract among the 455 people in the placebo group – quite a remarkable reduction.
“This is important because cancers of the upper GI tract are difficult to diagnose and often go unnoticed early,” Mathers says.
However, there was one area where the resistant starch didn’t make much of a difference — in the rate of colon cancer.
More work is needed to figure out exactly what’s going on here, but the team has some ideas.
“We think that resistant starch may reduce cancer development by altering the bacterial metabolism of bile acids and by reducing those types of bile acids that can damage our DNA and ultimately cause cancer,” Mathers says.
“However, this requires further research.”
To be clear, this trial has been conducted in people who are already genetically predisposed to developing cancer and does not necessarily apply to the general public. But there is still much to learn from better understanding how resistant starch can help protect against cancer.
The original trial was called the CAPP2 study, and the team is now conducting a follow-up called CaPP3, which involves more than 1,800 people with Lynch syndrome.
While it may sound worrying that colorectal cancer rates seemed unaffected by the resistive starch, don’t worry, the study had some good news on that front, too.
The original trial also looked at whether taking aspirin daily could reduce the risk of cancer. In 2020, the team published results showing that aspirin reduced the risk of colorectal cancer in Lynch syndrome patients by 50 percent.
“Patients with Lynch syndrome are at high risk because they are more likely to develop cancer, so it is vital to discover that aspirin can cut the risk of colon cancers and resistant starch by half,” says geneticist Sir John Burns of Newcastle University. the trial with Mathers.
“Based on our trial, NICE [the UK’s National Institute for Health and Care Excellence] now recommend aspirin for people at high genetic risk of cancer, the benefits are clear – aspirin and resistant starch work.”
The research was published in Research on cancer prevention.