Assessment of dietary quality in American adults and its association with sociodemographic and metabolic syndrome-related biomarkers: Comparison of two samples from Midlife in the United States (MIDUS) study (Preprint)

BACKGROUND An unhealthy diet ranks among the top contributors to the burden of noncommunicable chronic disease and death in the US, highlighting the importance of evaluating diet quality in population-based studies, such as the MIDUS (Midlife in the United States) cohort. OBJECTIVE 1) To develop a simple tool (MIDUS healthy eating index (MIDUS-HEI)) to evaluate diet quality more broadly and consistently in subjects enrolled at different time points of the MIDUS study, and 2) To use this score in assessing the cross-sectional association of the overall dietary pattern with sociodemographic and health variables in MIDUS participants. METHODS We used extant food intake data collected from participants in two biomarker sub-studies of the MIDUS Core and Refresher national samples to design, test, and validate the dietary score tool through its cross-sectional association with available sociodemographic and health variables. RESULTS Our results indicated that better dietary quality was observed among older adults as well as white subjects and those with a higher educational status. According to the MIDUS-HEI score, dietary quality improved over time in MIDUS Refresher cohort compared to the MIDUS Core cohort. However, race-based disparities in dietary quality increased between the two survey times. Regarding health variables, MIDUS-HEI score was inversely associated with the prevalence of metabolic syndrome (MetS) and most of its diagnostic criteria. CONCLUSIONS The MIDUS-HEI score is a useful indicator of quality of diet intake, exhibiting an inverse cross-sectional association with unhealthy diet-related biomarkers and MetS. Also, sociodemographic-dependent variations of this index were consistent with similar dietary pattern scores evident in other epidemiological studies. Thus, MIDUS-HEI represents a valuable tool for further analysis and discovery using the wide multidisciplinary scope of MIDUS.