Background & aims: Dietary quality and patterns have been associated with reduced incidence and increased colorectal cancer (CRC) survival. Two validated scores representing the quality of diet defined respectively by their content in micronutrients (nutritional quality index (INQ)) and antioxidant (dietary antioxidant index (DAI)) were used for assessing dietary quality. INQ standardizes all micronutrients using the recommended values and adjusts nutrients intakes based on total energy. Major dietary antioxidants are standardized based on the global mean and then divided by the global standard deviation to calculate the DAI. We hypothesize that a quality diet with higher scores of DAI can reduce CRC odds.
Methods: In this hospital-based case-control study, 207 definite CRC cases and 220 controls met the inclusion criteria. Cases and controls were frequency-matched for age (±5 years) and sex. A 168-item semi-quantitative food frequency questionnaire was completed. Adjusted and unadjusted odds ratios (OR) and 95% confidence intervals (CI) were reported in logistic and multivariable regression models.
Results: DAI as a continuous (OR = 0.91, 95% CI: 0.85-0.98) and as a categorical (OR = 0.58, 95% CI: 0.37-0.92) variable and the INQs of vitamin A (OR = 0.30, 95% CI: 0.10-0.89), riboflavin (OR = 0.55, 95% CI: 0.32-0.94), magnesium (OR = 0.37, 95% CI: 0.18-0.77) and selenium (ORmultiple adjusted = 0.55, 95% CI: 0.36-0.86) in the regression crude models, and multivariable adjustments significantly have a protective association in reducing the odds of CRC (all p-values <0.05).
Conclusions: It can be concluded that dietary antioxidants, including vitamins A, C, E, zinc, selenium, and manganese from a high-quality diet, including vegetables, whole grains, and fruits, can significantly reduce CRC incidence.
Keywords: Beta-carotene; Cancer; Nutritional assessment; Selenium; Vitamin A.
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