July 11, 2007

Type of fat important in reducing colorectal cancer risk

Although high intake of fat has been associated with an increase in cancer risk, a case-control study published in the July 15, 2007 issue of the American Journal of Epidemiology concluded that a greater intake of omega-3 polyunsaturated fatty acids may be protective against colorectal cancer.

Professor Harry Campbell of the College of Medicine and Vet Medicine at the University of Edinburgh in Scotland, and his associates paired 1,455 men and women diagnosed with colorectal cancer with an equal number of healthy control subjects matched for age, gender and region of residence. Lifestyle and food frequency questionnaires regarding the year prior to diagnosis or recruitment to the study were completed by all participants in the current analysis. Total fatty acid, as well as saturated fatty acid, monounsaturated fatty acid, omega-6 polyunsaturated fatty acid, omega-3 polyunsaturated fatty acid, trans-fatty acid, and trans-monounsaturated fatty acid intake was determined. Intake levels of individual fatty acids, such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), were also calculated.

Participants without colorectal cancer reported significantly lower daily calorie intake than those diagnosed with the disease. Although total and trans-monounsaturated fatty acid intake were associated with increased colorectal cancer risk, adjustment for calorie intake negated this effect. Greater intake of omega-3 fatty acids, EPA, and DHA were dose-dependently associated with reduced colorectal cancer risk. Participants whose omega-3 intake was in the top one-fourth of participants experienced a 37 percent lower risk of colorectal cancer than those who intake was in the lowest quarter, while having EPA and DHA in the top fourth was associated with a 41 and 37 percent lower risk.

The authors conclude, "The observed different effects of different types of fatty acids underline the importance of type of fat in the etiology and prevention of colorectal cancer. "

—D Dye

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