A four-year study exploring the relationship between a high-fiber diet and colon cancer reveals that people who eat more dry beans have less risk of developing the disease.

The Polyp Prevention Study has revealed that people who significantly increase their consumption of dry beans, such as pinto and navy beans and lentils, have the largest risk reduction of developing pre-cancerous polyps in the colon.

The study randomized 2,079 high-risk men and women over age 35, into either a low-fat, high-fiber and fruit-and-vegetable-enhanced diet group, or another group that didn’t change its diet, and followed the groups for four years. In 2000, it was reported that the study showed no change in recurrence rates of colorectal polyps, due to the diet change. However, new findings reveal that those study participants who ate up to four-times their pre-study consumption of dry beans, do show reduced rates of reoccurrence.

“This is the first reported protective association between dry-bean intake and advanced polyp recurrence, and more research is needed,” said lead researcher Elaine Lanza, Ph.D. “USDA guidelines call for Americans to consume at least three cups of beans per week—that’s six times the current consumption for most people.”

Dry beans have non-digestible carbohydrates, which, when converted during digestion, have anti-cancer and anti-inflammatory properties. Beans also contain other possible cancer-fighting properties, including saponins, phytosterols and a form of vitamin E.