Does a banana a day keep the doctor away?

A study that examined patients with a high risk of developing various types of cancer found that eating bananas, rice and certain grains can reduce their risk of getting sick by almost half. 

The banana was concealed under a plastic bag (photo credit: PEXELS)
The banana was concealed under a plastic bag
(photo credit: PEXELS)

Many studies have shown the connection between good nutrition and a lower risk of cancer. Now a new study on people with a hereditary risk for a wide range of cancers has found that resistant starch may play a significant role in protecting against certain diseases. 

Resistant starch is found in oats, cereals, green bananas, pasta and rice. Researchers found that the fermented fiber in these foods reduces the risk of certain types of cancer by more than half.

The long-term study followed nearly 1000 patients with Lynch syndrome (HNPCC)  an inherited disorder that increases the risk of many types of cancer, particularly cancers of the colon (large intestine) and rectum i.e.colorectal before age 50. 

This is important because upper gastrointestinal cancer is difficult to diagnose and often goes undetected at an early stage."

Professor John Mathers

The findings were published in Cancer Prevention Research, a journal of the American Association for Cancer Research.

Professor John Mathers, an expert in human nutrition at Newcastle University, England told IFLScience that scientists saw that resistant starch caused a 60% reduction in the development of various cancers. The effect was most evident in the upper part of the intestine. He said: "This is important because upper gastrointestinal cancer is difficult to diagnose and often goes undetected at an early stage."

 Dividing cancer cell (credit: INGIMAGE) Dividing cancer cell (credit: INGIMAGE)

Why does starch protect against cancer?

According to the researchers, resistant starch nourishes the growth of beneficial bacteria in the intestines which produces chemicals that prevent diseases such as cancer. This explains why eating more dietary fiber each day may reduce the chance of colon cancer.

The benefits of resistant starch in lowering cancer risk weren’t consistent across all types of disease, but for some cancers the risk was more than halved. The effect was seen in people who took a resistant starch powder supplement every day for two years and were followed for 10 years after stopping the supplement.

Cancers of the upper gastrointestinal tract were markedly associated with improvement under starch intake including cancers of the esophagus, stomach, biliary tract, pancreas, and duodenum. The study also found that aspirin carries benefits for people with Lynch syndrome, cutting the risk of colon cancer in half.

Despite the promising insight into the effect of resistant starch supplements on certain cancers for some people, researchers warn that more studies are needed to substantiate the conclusions. 

"The results are exciting but the strength of the protective effect on the upper gastrointestinal tract was unexpected so further research is needed to replicate these findings," said Professor Tim Bishop of the University of Leeds, who also helped lead the trials.