Foods high in resistant starch, like peas, beans and other legumes, can protect against colorectal cancer, say researchers.

Resistant starch cannot be digested so it ends up in the bowel in pretty much the same form it entered your mouth. Once in the bowel this resistant starch does some important things, including decreasing bowel pH and transit time, and increasing the production of short-chain fatty acids. These effects promote the growth of good bugs while keeping bad bugs at bay.

Now, a University of Colorado Cancer Center review has shown that resistant starch also helps the body resist colorectal cancer through mechanisms including killing pre-cancerous cells and reducing inflammation that can otherwise promote cancer.

"Resistant starch is found in peas, beans and other legumes, green bananas, and also in cooked and cooled starchy products like sushi rice and pasta salad," said Janine Higgins, PhD, CU Cancer Center investigator and associate professor of Pediatrics at the University of Colorado School of Medicine.

"You have to consume it at room temperate or below - as soon as you heat it, the resistant starch is gone. But consumed correctly, it appears to kill pre-cancerous cells in the bowel," Higgins suggested.

Higgins found that rats fed resistant starch showed decreased numbers and sizes of lesions due to colorectal cancer, and an increased number of cells that express the protein IL-10, which acts to regulate the body`s inflammatory response.

"Resistant starch may also have implications for the prevention of breast cancer," Higgins noted.

"There are a lot of things that feed into the same model of resistant starch as a cancer-protective agent. Much of this information currently comes from rodent models and small clinical trials but the evidence is encouraging," Higgins said.

The research was published in this month`s issue of the journal Current Opinion in Gastroenterology.