Fruit and vegetable intakes are associated with lower risk of colorectal adenomas

Abstract

Many phytochemicals in fruits and vegetables have been shown to have cancer-inhibitory effects in animal studies. These effects on cancer, however, have not been clearly demonstrated in human studies. This study investigated the association between fruit and vegetable intakes and the risk of adenomatous polyps. Participants were part of the Tennessee Colorectal Polyp Study. Eligible participants aged 40-75 y were recruited from patients undergoing colonoscopy at 2 medical centers in Nashville, Tennessee from 2003 to 2005. Cases had at least one adenoma and controls were polyp free. Dietary intake was assessed using a self-administered FFQ. Associations between dietary intakes and adenoma risk were evaluated using unconditional logistic regression with restricted cubic function spline. In multivariate analyses of 764 cases and 1517 controls, increased intakes of total fruits, berries, fruit juice, and green leafy vegetables were associated with reduced adenoma risk. The odds ratio for upper tertile intake compared with lower was 0.66 (95% CI = 0.51-0.86) for total fruits, 0.64 (95% CI = 0.47-0.87) for berries, 0.72 (95% CI = 0.56-0.92) for fruit juice, and 0.74 (95% CI = 0.58-0.96) for green vegetables. This study provides additional evidence that high total fruit intake and certain fruit and vegetable intakes may be associated with a reduced risk of colorectal adenomas.

FIGURE 1

Association between total fruit intake and adenoma risk in categorical and spline models. Spline regression demonstrated a nonlinear relationship between risk and fruit intake, whereas the categorical regression provided a step function of the intake with an underestimate of risk reduction in the higher intake range. Estimates were based on n = 764 cases and n = 1517 controls.