Diet and the risk of Colon Cancer

A number of studies have confirmed a link between diet and the risk of colorectal cancer. In one study of 150,000 adults reported in the Journal of the American Medical Association, people who ate the most red and processed meat over a 20-year period had a 50% greater risk of developing colorectal cancer than those who consumed little meat.

Individuals who ate more poultry and fish than meat had a 70% lower risk of colon cancer. Likewise, a large European study of close to half a million people found that those who ate the most red and processed meat had the highest risk of colorectal cancer, while those who ate the most fish had the lowest risk of colorectal cancer. Eating poultry neither increased nor decreased the risk of colorectal cancer.

Finally, a third study, performed in Japan, found that women who followed a traditional Japanese diet (high in salted fish, rice, miso soup, and pickled vegetables) or a typical Western diet (high in meat and cheese) had a higher risk of colon cancer than those who consumed a healthy diet (high in vegetables, fruits, and soy). Men did not have a higher risk of colorectal cancer as a result of eating a Japanese or Western diet.

Women who consume a diet with a high glycemic load—one that includes lots of simple and complex sugars—may be more likely to develop colorectal cancer than those who eat low-glycemic diets. Dietary factors have been strongly linked to colorectal cancer, but the long-term effects of a high-glycemic load have remained unclear.

In their study, which was reported in the Journal of the National Cancer Institute, researchers followed more than 38,000 women for an average of almost eight years. Participants were asked to record all the food they ate at the study’s onset. By the end of the study, 174 women had developed colorectal cancer. Women with the highest glycemic load were almost three times as likely to develop cancer as those who ate a low-glycemic diet.

High total carbohydrate and fructose intakes were also associated with an elevated risk of colon cancer. The study authors remark that trying to establish a link between diet and disease is difficult because dietary factors are interrelated and complex. Although a high glycemic load may be associated with an increased risk of colorectal cancer, other variables such as body weight, level of physical activity, smoking, alcohol use, and nutrient intake probably play a role as well.

Johns Hopkins Health Alerts February 27, 2007