Socioeconomic Inequalities in the Association Between Diet Quality and Incident Cardiovascular Diseases: A Prospective Study in the Netherlands

Background: Individuals with lower socioeconomic position (SEP) have higher risks of cardiovascular diseases (CVD), with diet quality being a crucial risk factor. However, whether the association between diet quality and CVD differs across SEP (education and income) groups is unclear, which was examined in this study. Methods: This study included participants aged 30-80 years, free of CVD at baseline, from the Dutch Lifelines cohort. The Lifelines Diet Score, a diet quality indicator based on Dutch dietary guidelines, was calculated with data assessed by a 110-item food frequency questionnaire. Cox proportional hazards models were used to assess the association between diet quality and incident CVD (the first non-fatal major cardiovascular event), and whether this association was modified by SEP, adjusted for age, sex, energy intake, alcohol intake, smoking, TV watching time, moderate-to-vigorous physical activity, sleep duration, social/hobby clubs participation, chronic stress, family history of CVD, and BMI. Results: Of 82,360 participants included, 2827 incident CVD cases were identified (median follow-up 7.4 years, incidence rate 4.7 per 1000 person-years). Education modified the association between diet quality and incident CVD (P-interaction = 0.033). Comparing the poorest to the best diet quality quartiles, hazard ratios (95%CI) were 1.27 (1.06, 1.51) in low, 1.28 (1.06, 1.54) in middle, and 0.98 (0.76, 1.27) in high education group. Conclusions: For low- and middle-education populations, poor diet quality was associated with disproportionately higher risks of incident CVD; improving diet quality may therefore enhance their health. However, to address persistent health inequalities, health policies should tackle broader structural factors of diet and SEP.