Changes in Diet Quality over 10 Years Are Associated with Baseline Sociodemographic and Lifestyle Factors in the Multiethnic Cohort Study

Abstract

ABSTRACT Background Trends in diet quality among US adults indicate a steady improvement, but data on longitudinal individual-level changes in diet quality are still limited. Objective We examined changes in diet quality over 10 y and sought to determine whether baseline sociodemographic and lifestyle factors predicted the changes in a multiethnic population. Methods Data were from 63,255 African American, Native Hawaiian, Japanese American, Latino, and white men and women (45–75 y old at baseline) in the Multiethnic Cohort, who completed a quantitative food frequency questionnaire at baseline (1993–1996) and 10-y follow-up (2003–2007) and had no prevalent cancer or heart disease at either survey. Overall diet quality was measured by use of the Healthy Eating Index–2015 (HEI-2015), the Alternative Healthy Eating Index–2010 (AHEI-2010), the alternate Mediterranean Diet score, and the Dietary Approaches to Stop Hypertension (DASH) score. We used a general linear model with adjustment for covariates to compare diet quality changes by baseline characteristics in men and women separately. Results Overall diet quality improved over 10 y by 3.2 points in men and 2.9 in women assessed using the HEI-2015, although scores for some components worsened (saturated and trans fats, indicating increased intake) or remained unchanged at a low quality level (whole grains, dairy, and sodium). In multivariable models where changes in HEI-2015, AHEI-2010, and DASH were harmonized to a 100-point score, greater increases in scores in both men and women were found for Japanese American ethnicity (increase by 0.5–4.7 in the 3 scores, P < 0.03), higher education (by 0.5–1.5, P ≤ 0.001), normal weight (BMI 18.5 to <25, by 0.6–2.5, P ≤ 0.01), nonsmoking (by 1.5–2.7, P < 0.001), higher moderate/vigorous physical activity level (by 0.3–0.8, P ≤ 0.04), and multivitamin use (by 0.4–0.7, P < 0.001) at baseline. Conclusions Sociodemographic and lifestyle factors, closely associated with diet quality, also predicted subsequent changes in diet quality over time in this multiethnic population.