Secular Trends in Regional Differences in Biomarkers of Dietary Exposure and Inflammation among American Adults: NHANES III, 1988–1994 to C‐NHANES 1999–2010

Abstract

Regional disparities in health outcomes, including age‐adjusted mortality rates, are evident at several different levels of geographic aggregation in the US. The regional gradient of health outcomes generally reveal the South and Midwest regions to compare unfavorably with the West and Northeast regions. Moreover, regional gaps in health outcomes have persisted over time. We used data from several NHANES surveys to examine time trends in the association of census region of residence (Northeast, Midwest, West, and South) with serum concentrations of several nutritional biomarkers among American adults aged ≥20 years. The biomarkers available for this period included: serum (and RBC) folate and c‐reactive protein (CRP) (NHANES 1988–1994 to 2009–2010, n>40,000); α‐carotene, β‐carotene, β‐cryptoxanthin, lutein‐zeaxanthin, lycopene, and vitamin D (NHANES 1988–1994 to 2001–2006; n>26,500), vitamin E (NHANES 1988–1994, 1999–2001 and 2005–2006, n> 26,500); vitamin C (NHANES 1988–1994 and 2003–2006, n>21,900); and vitamin B‐6 (NHANES 2003–2008, n>12, 800). In multivariable regression models adjusted for covariates, the interactions of survey cycle and region were not significant, indicating similar secular trends among regions. Main effect of region was significant (P<0.01) for all biomarkers except serum vitamin B‐6. Mean serum concentrations of all examined biomarkers were lower but that of CRP were higher in the South census region of the country. Generally the observed regional gradients in biomarker concentrations were in the same direction as those reported for health outcomes.Support or Funding InformationFunded by National Institute of Aging grant (AG046540) (AKK).