Starch in green bananas can slash risk of some cancers by over 60%, study finds

If you like your bananas slightly green, you may be getting some unexpected health benefits.

A 20-year study has found that starch in unripe bananas can reduce the risk of some cancers by more than 60 per cent, Euronews reports. 

Along with bananas, this type of starch is also found in oats, cereals, pasta, rice, peas and beans.

The study, led by experts at the Universities of Newcastle and Leeds and published in the journal Cancer Prevention Research, could have important implications in reducing cancers in the upper part of the gut, which doctors say can be hard to spot and diagnose.

Over the course of the study, participants took a dose of this starch - called resistant starch - equivalent to that you would get from eating a banana that isn’t overly ripe and is still a bit green.

Some 1,000 patients with Lynch syndrome - an inherited disorder which increases the risk of cancer, particularly in the large intestine and rectum - took the dose for an average of two years.

The study revealed that while the starch didn’t affect cancers in the bowel, it did reduce the incidence of cancers in other parts of the body by more than half.

It had a particular effect on cancers of the upper gastrointestinal (GI) tract, including oesophageal, gastric, biliary tract, pancreatic and duodenal cancers.

The effect of taking the supplement was apparent for 10 years after patients stopped taking it.

“We found that resistant starch reduces a range of cancers by over 60 per cent. The effect was most obvious in the upper part of the gut,” John Mathers, a professor of human nutrition at Newcastle University, said in a statement.

“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 can be taken as a powder supplement and is found naturally in peas, beans, oats and other starchy foods, he added.