Index-based dietary patterns and risk of colorectal cancer: The NIH-AARP Diet and Health Study Free

B50

An index-based dietary pattern calculates a numerical score based on a priori knowledge about nutrition and is one way to address the complexity of diet and the likely interaction between multiple dietary components. We compared how four indexes_the Healthy Eating Index-2005 (HEI-2005), Alternate Healthy Eating Index (AHEI), Mediterranean Diet Score (MDS), and Recommended Food Score (RFS)_are associated with colorectal cancer in the NIH-AARP Diet and Health Study (n=492,382). To calculate each score, data from a 124-item food-frequency questionnaire completed by all participants at study entry (1995-96) were merged with the MyPyramid Equivalents Database (version 1.0). Other variables used to construct the scores included energy, specific nutrients, multivitamins, and alcohol. Models were stratified by sex and adjusted for age, ethnicity, education, body mass index, smoking, and physical activity (and menopausal hormone therapy in women). During approximately 5 years of follow-up, 3,110 newly incident colorectal cancer cases were ascertained. Although the diet quality indexes differ in design, a similarly decreased risk of colorectal cancer was observed across all indexes for men when comparing the highest scores with the lowest: HEI-2005 relative risk (RR) = 0.72 (95% CI: 0.62, 0.83), AHEI RR = 0.70 (95% CI: 0.61, 0.81), MDS RR = 0.72 (95% CI: 0.63, 0.83), and RFS RR = 0.75 (95% CI: 0.65, 0.87). For women, a significantly decreased risk was found with the HEI-2005; however, the estimates and confidence intervals for the AHEI were very similar to those of the HEI-2005. Index-based methods illustrate that dietary patterns that are consistent with given dietary guidelines are associated with a reduced risk of colorectal cancer. This work is particularly important as dietary guidance and messages about cancer-preventive dietary patterns continue to be refined.