Trial Shows That Resistant Starch May Reduce Hereditary Cancer Risk

An international trial led by researchers at Newcastle University and the University of Leeds has shown that adding a starch supplement to the diet can help to reduce the risk of developing certain forms of cancer.

Cancer News

The trial, whose results appeared in the journal Cancer Prevention Research, involved almost 1,000 people with Lynch syndrome from across the world. It showed that certain cancer risks can be cut greatly by consuming resistant starch, which is found in many foods.

“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,” said Professor John Mathers, a professor of Human Nutrition at Newcastle University in the UK. “This is important as cancers of the upper GI tract are difficult to diagnose and often are not caught early on.”

What is, perhaps, most interesting was that the effect of the supplement lasted for 10 years after its last use.

What is resistant starch?

Resistant starch is a kind of carbohydrate that goes through the small intestine undigested. It ferments when it gets to a person’s large intestine, providing food for beneficial bacteria in the gut. In essence, this lower-calorie starch functions as a dietary fiber and offers multiple health benefits.

The starch is naturally present in a wide variety of foods, including oats, cooked and cooled rice or pasta, slightly green bananas, and beans. Also called fermentable fiber, it is available for purchase and use in powder form as well.

“We think that resistant starch may reduce cancer development by changing the bacterial metabolism of bile acids to reduce those types of bile acids that can damage our DNA and eventually cause cancer,” said Mathers. “However, this needs further research.”

The dose of resistant starch used in this trial is comparable with eating a banana that is not too ripe or soft daily, as per Mathers.

Studying anti-cancer effects

This double-blind trial, which is called CAPP2, is a planned 10-year follow-up study.

Almost 1000 people with Lynch syndrome were given powdered starch supplement, aspirin, or a placebo daily for an average of two years between 1999 and 2005. These patients are typically at a greatly increased risk of developing certain cancers.

Researchers failed to notice any significant difference between those who took the starch supplement or aspirin and those who had the placebo when treatment ended. However, they expected to see the effect in the long term, so they planned to do a follow-up study.

During the follow-up, the team found that starch treatment had no positive impact on bowel cancers. It, however, produced notable effects on cancers occurring in other parts of the body.

Resistant starch was especially helpful in reducing cancers of the upper gastrointestinal (GI) tract. These include cancers of the esophagus, stomach, pancreas, and duodenum.

Only five new upper GI cancer cases were observed among the 463 patients that got resistant starch when the team followed up. By contrast, 21 new cases were seen among the 455 placed on a placebo.

Also, earlier research that was published as part of this trial showed that aspirin cut large bowel cancer risk by 50 percent.

“Patients with Lynch syndrome are high-risk as they are more likely to develop cancers, so finding that aspirin can reduce the risk of large bowel cancers and resistant starch [can reduce the risk of] other cancers by half is vitally important,” said Professor Sir John Burn, a Newcastle University geneticist who led the trial with Mathers.

The National Institute for Health and Care Excellence (NICE) in the UK now recommends aspirin for people at high risk of hereditary cancer based on this trial, Burn stated.

The research team is now moving on to CaPP3, an international follow-up trial involving over 1,800 patients with Lynch syndrome. It will be looking into whether smaller, safer aspirin doses can reduce the risk of developing cancer.