Ethnicity is an independent correlate of biomarkers of micronutrient intake and status in American adults

Diet may be among the factors that mediate the acknowledged ethnicity and socioeconomic differentials in health. Biomarkers of nutritional exposure avoid reliance on biased self-reports of diet and allow an objective assessment of dietary differentials associated with ethnicity and socioeconomic position. We used data from the NHANES III (n = 13113) and NHANES 1999-2002 (n = 7246) to examine ethnic, education, and income differentials in serum concentrations of nutrients of putative public health importance (vitamins C, D, and E, folate, carotenoids, selenium, and ferritin) in U.S. adults. Multiple regression methods were used to adjust for covariates and complex survey design to examine these associations. The serum beta-cryptoxanthin and lutein + zeaxanthin concentrations, adjusted for education and income, were higher in non-whites (P < 0.0001) relative to non-Hispanic whites. Non-Hispanic blacks had lower serum vitamins C and D, folate, and selenium concentrations relative to non-Hispanic-whites. The biomarker profile (except vitamin D, and folate and ferritin in women) of Mexican-Americans was comparable or better relative to non-Hispanic-whites. Ethnicity associations with mean biomarker concentrations generally paralleled these associations with the proportion of the population at risk of marginal concentrations. Education was an independent positive predictor of serum concentrations of several carotenoids and vitamin C (P <= 0.01). Both education and income were independent inverse predictors of risk of marginal vitamin C concentration in men (P <= 0.003). Relative to income, ethnicity and education were stronger independent predictors of several outcomes. Ethnic differences in status of several micronutrients persisted after adjustment for education and income, suggesting the importance of ethnicity-specific nutrition interventions.