Most of us would shudder at the thought of eating an unripe banana, but a new study suggests that eating one daily could significantly decrease the risk of getting cancer.

Yes, you read that right! Scientists conducted a study on participants with a high hereditary risk of cancer, giving them a diet that’s high in resistant starch, which bananas are abundant with but only when they are green.

Resistant starch is a type of carbohydrate that feeds your colon with beneficial gut bacteria. It’s typically found in raw potatoes, oats, cereals, and beans.


The study, which was led by experts at the Universities of Newcastle and Leeds, examined nearly 1,000 patients with Lynch syndrome – a genetic condition that leaves people vulnerable to a range of cancers.

Between 1999 to 2005, the participants began taking either resistant starch in powder form every day for two years or a placebo. The daily dose of resistant starch that they took was equivalent to one unripe banana.


At the end of the study, there were no drastic differences between the group that regularly consumed resistant starch and those taking the placebo.

However, the research team designed the study for further follow-ups to measure its long-term effects.

While it did not reduce the risk of bowel cancer, the researchers discovered that the diet reduced the participants’ risk of cancer developing in other parts of the body by up to 60 per cent.

This ‘protective’ effect was especially evident for upper gastrointestinal cancers including oesophageal, gastric, biliary tract, pancreatic and duodenum cancers.

The benefits were observed to last for up to 10 years even after the participants ceased taking the supplement. The experts are hopeful that the findings could benefit the general population and not just people diagnosed with Lynch syndrome.


During the follow-ups, only five cases of upper gastrointestinal cancers among the 463 participants who had taken the resistant starch were reported. On the other hand, 21 were diagnosed with the disease among the 455 participants who were on the placebo.

Professor John Mathers, an expert in Human Nutrition at Newcastle, detailed: ‘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. This is important as cancers of the upper gastrointestinal tract are difficult to diagnose and often are not caught early on.

'The dose used in the trial is equivalent to eating a banana daily before they become too ripe and soft. The starch in bananas resists digestion 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 continued.


Professor Mathers added: '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,' he added.

Professor Tim Bishop, who was also involved in the study, said the results were promising but also mentioned that further research was needed.


'The results are exciting but the magnitude of the protective effect in the upper gastrointestinal tract was unexpected, so further research is required to replicate these findings,' he explained.

Eating green bananas doesn’t so bad anymore, does it? What are your thoughts on this study? Better yet, will you be incorporating unripe bananas into your diet? (Don’t forget to consult with your GP before making any lifestyle changes!) Let us know in the comments!

Learn more about the surprising benefits of green bananas by watching the video below: