Socio-economic indicators and diet quality in an older population

Purpose: To examine the strength and independence of associations between three major socio-economic indicators (income, education and occupation) and diet quality (DQ) at baseline and after 20-year follow-up. Methods: Cross-sectional and longitudinal analyses using data collected in the Rotterdam Study, a prospective population-based cohort. Participants were categorised according to socio-economic indicators (education, occupation and household income) measured at baseline (1989-1993). Participants aged 55 years or older were included (n = 5434). DQ was assessed at baseline (1989-1993) and after 20 years (2009-2011) and quantified using the Dutch Healthy Diet Index, reflecting adherence to the Dutch guidelines for a healthy diet; scores can range from 0 (no adherence) to 80 (optimal adherence). Linear regression models were adjusted for sex, age, smoking status, BMI, physical activity level, total energy intake and mutually adjusted for the other socioeconomic indicators. Results: At baseline, scores on the Dutch Healthy Diet Index were 2.29 points higher for participants with the highest level of education than for those with the lowest level (95%CI = 1.23-3.36); in addition, they were more likely to have a higher DQ at follow-up (beta = 3.10, 95%CI = 0.71-5.50), after adjustment for baseline DQ. In contrast, higher income was associated with lower DQ at follow-up (beta = -1.92, 95%CI = -3.67, -0.17), whereas occupational status was not associated with DQ at baseline or at follow-up. Conclusion: In our cohort of Dutch participants, a high level of education was the most pronounced socio-economic indicator of high DQ at baseline and at follow-up. Our results highlight that different socio-economic indicators influence DQ in different ways.