Red meat eaters should consume foods with a particular type of starch to lessen their risk of bowel cancer, Australian research suggests.
Previous studies have shown that a high red meat intake may increase the risk of bowel cancer, also known as colorectal cancer.
But new evidence suggests red meat and resistant starch – a type of starch that goes all the way through the small intestine without being digested at all – have opposite effects on bowel cancer-promoting molecules.
Resistant starch is found in bananas that are still green, whole grains, beans, chickpeas, lentils and cooked and cooled potatoes, such as potato salad.
Lead author Dr Karen Humphreys, from Adelaide’s Flinders University, said with meat consumption on the rise, the findings highlight the importance of resistance starch in our diet.
“Red meat-eaters should be making a conscious effort to get more resistant starch into their diets,” she said.
Resistant starch is readily fermented by microbes in the gut to produce beneficial molecules called short-chain fatty acids, such as butyrate, which have opposite effects on cancer-promoting molecules, she said.
Each year, about 14,000 people are diagnosed with bowel cancer in Australia. It’s most common in people over 50, but it can occur at any age.
Dr Humphreys studied 23 healthy volunteers between the ages of 50 and 75.
Half of the participants ate a diet high in red meat for four weeks and after a four-week break had a red meat and resistant starch diet for a further four weeks. The other half of the volunteers followed the same diet but in the reverse order.
When the volunteers had the red meat only diet (300 grams of lean red meat every day) they recorded a 30 per cent increase in the levels of cancer-promoting genetic molecules in their rectal tissue, as well as an associated increase in cell growth, she said.
When participants consumed the red meat plus 40 grams of resistant starch every day they recorded baseline levels of the cancer-promoting genetic molecules.
The study, published in US journal Cancer Prevention Research, was funded by the National Health and Medical Research Council, the CSIRO and the Flinders Medical Centre Foundation.