Whole grains decrease colorectal cancer risk, report states

07 Sep 2017 --- Daily consumption of whole grains, such as brown rice or whole-wheat bread, reduces colorectal cancer risk, with the more you eat the lower the risk. This is according to a report by the American Institute for Cancer Research (AICR) and the World Cancer Research Fund (WCRF).

“Diet, Nutrition, Physical Activity and Colorectal Cancer” also found that regularly consumption of processed meats, such as hot dogs and bacon, increases the risk of this cancer. There was strong evidence that physical activity protects against colon cancer.

“Colorectal cancer is one of the most common cancers, yet this report demonstrates there is a lot people can do to dramatically lower their risk,” says Edward L. Giovannucci, MD, ScD, lead author of the report and professor of nutrition and epidemiology at the Harvard TH Chan School of Public Health. 

“The findings from this comprehensive report are robust and clear: Diet and lifestyle have a major role in colorectal cancer.”

The new report evaluated the scientific research worldwide on how diet, weight and physical activity affect colorectal cancer risk. The report analyzed 99 studies, including data on 29 million people, of whom over a quarter of a million were diagnosed with colorectal cancer.

Other factors found to increase colorectal cancer include:

• Eating high amounts of red meat (above 500 grams cooked weight a week), such as beef or pork
• Being overweight or obese
• Consuming two or more daily alcoholic drinks (30 grams of alcohol), such as wine or beer

Lowering risk with fiber and activity
The report concluded that eating approximately three servings (90 grams) of whole grains daily reduces the risk of colorectal cancer by 17 percent. It adds to previous evidence showing that foods containing fiber decreases the risk of this cancer.

For physical activity, people who are more physically active have a lower risk of colon cancer compared to those who do very little physical activity. Here, the decreased risk was apparent for colon and not rectal cancer.

In the US, colorectal cancer is the third most common cancer among both men and women, with an estimated 371 cases diagnosed each day. AICR estimates that 47 percent of US colorectal cancer cases could be prevented each year through healthy lifestyle changes.

Fish, fruits and vegetables
The report found other links between diet and colorectal cancer that were visible but not as clear. There was limited evidence that risk increases with low intake of both non-starchy vegetables and fruit. A higher risk was observed for intakes of less than 100 grams per day (about a cup) of each.

The research continues to emerge for these factors, but it all points to the power of a plant-based diet, says Alice Bender, MS, RDN, AICR Director of Nutrition Programs. 

“Replacing some of your refined grains with whole grains and eating mostly plant foods, such as fruits, vegetables and beans, will give you a diet packed with cancer-protective compounds and help you manage your weight, which is so important to lower risk,” Bender says.