Do Fruits and Veggies Reduce Risk for Colorectal Cancer?

Instructions to patients with regard to diet and colorectal cancer (CRC) often include decreasing consumption of dietary fat — especially animal fat — and increasing consumption of fiber, fruits, vegetables, and low-fat dairy products. However, increased intake of whole grains has not been effective in reducing the recurrence of adenomas, and epidemiologic data on the effect of fruits and vegetables have been mixed.

Now, researchers have conducted a meta-analysis of 19 cohort studies investigating fruit and vegetable intake and CRC risk. All 19 studies were included in a comparison between highest and lowest intakes; 15 were included in a dose-response analysis. Five studies were conducted in Europe, 10 in the U.S., and 4 in Asia.

The relative risk for CRC with highest versus lowest intake was 0.92 (95% confidence interval, 0.86–0.99) for fruits and vegetables and 0.90 (95% CI, 0.83–0.98) for fruits alone. For fruits, the dose-response analysis suggested a nonlinear association, with most of the risk reduction occurring when low intake increased to about 100 g per day. High vegetable intake also offered significant protection (RR, 0.91; 95% CI, 0.86–0.96). The benefits were restricted to colon cancer, and the risk reduction was nonlinear, with the greatest reduction occurring when low intake increased to about 100 g per day.