Could a diet that leads to inflammation increase the risk of developing colorectal cancer?
By Lindsey Konkel
Inflammation is the body’s response to injury or infection. In the short term, it can be helpful. Yet chronic inflammation—a state in which the immune system is persistently activated—is a known risk factor for cancer.
Lifestyle factors such as drinking alcohol, smoking and being obese can contribute to chronic inflammation. A study published in the March 2017 issue of the Journal of Nutrition adds to a growing body of research suggesting that certain diets that promote inflammation are associated with increased colorectal cancer risk in some groups.
In the 1990s, 190,963 study participants from California and Hawaii filled out a questionnaire including questions about their diets. The researchers then rated the participants’ diets using the Dietary Inflammatory Index, which categorizes foods based on a literature review of the relationship between diet and inflammatory markers in the blood. In general, foods high in animal fat, animal protein and added sugars lead to more inflammation, while diets rich in fruits, vegetables and whole grains may help reduce inflammation.
Overall, the quartile of people whose diets were rated most pro-inflammatory were 21 percent more likely to develop colorectal cancer over 20 years of follow-up than the quartile of people whose diets contained the least-inflammatory foods. During the study period, 4,388 people—about 2.3 percent of total participants—developed colorectal cancer. (An estimated 4.3 percent of U.S. adults will be diagnosed with colorectal cancer in their lifetime.)
Within racial and ethnic groups, the researchers found statistically significant associations between colorectal cancer risk and pro-inflammatory diets for white, Japanese-American and Latino men, but not for African-American and native Hawaiian men. Among women, pro-inflammatory foods were only associated with significantly higher risk in native Hawaiians.
The findings are “just beginning to scratch the surface of dietary inflammation and cancer," says Brook Harmon,
a behavioral scientist at the University of Memphis in Tennessee who led the study. Other risk factors for colorectal cancer include family history, obesity, smoking and being African-American.