A trial shows that resistant starch has preventive benefits for people with a high risk of hereditary cancer.
A new trial in individuals with a high risk of hereditary cancer has shown that resistant starch, found in oats, cereals, and pasta, has a major preventative effect.
Experts from Newcastle University and the University of Leeds are collaborating on a double-blind 10-year follow-up trial about hereditary cancer and a diet supplement, supplemented with national cancer registry data for up to 20 years in 369 participants. The researchers have published their proposals in the journal Cancer Prevention Research.
Can a starch prevent hereditary cancer?
The international trial called CAPP2 included almost 1,000 patients with Lynch syndrome, a condition that increases the risk of hereditary cancers, and revealed that a regular dose of resistant starch reduced the likelihood of hereditary cancers in some parts of the body by over half. The starch did not affect cancers in the bowel. The effect of the starch was particularly noticeable in upper gastrointestinal cancers such as gastric and pancreatic.
The participants consumed the starch for around two years, and the effect was profound for approximately 10 years after ceasing use of the supplement.
“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,” explained Professor John Mathers, professor of Human Nutrition at Newcastle University. “This is important as cancers of the upper GI tract are difficult to diagnose and often are not caught early on.
“Resistant starch can be taken as a powder supplement and is found naturally in peas, beans, oats, and other starchy foods. The dose used in the trial is equivalent to eating a daily banana; before they become too ripe and soft, the starch in bananas resists breakdown and reaches the bowel where it can change the type of bacteria that live there.
“Resistant starch is a type of carbohydrate that is not digested in your small intestine, instead it ferments in your large intestine, feeding beneficial gut bacteria – it acts in effect, like dietary fibre in your digestive system. This type of starch has several health benefits and fewer calories than regular starch. 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. However, this needs further research.”
Aspirin found to reduce cancer of large bowel
The team, as part of the same trial, found that aspirin reduced cancer of the large bowel by 50%.
Professor Sir John Burn, from Newcastle University and Newcastle Hospitals NHS Foundation Trust who ran the trial with Professor Mathers, said: “When we started the studies over 20 years ago, we thought that people with a genetic predisposition to colon cancer could help us to test whether we could reduce the risk of cancer with either aspirin or resistant starch.
“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.
“Based on our trial, NICE now recommend Aspirin for people at high genetic risk of cancer, the benefits are clear – aspirin and resistant starch work.”
Long term study
Between 1999 and 2005, nearly 1,000 participants with a high risk of hereditary cancers took either resistant starch, aspirin, or a placebo for two years.
The researchers found no significant difference at the end of the treatment stage, but they expected a longer-term beneficial effect would occur. In the follow-up period, there were only five new cases of upper GI cancers in 463 participants who took the resistant starch compared with 21 in the 455 on the placebo.
The team are now leading the international trial, CAPP3, with over 1,800 people with a high risk of hereditary cancer to test if smaller, safer doses of aspirin can reduce hereditary cancer risk.