Serum retinol distributions in residents of the United States: third National Health and Nutrition Examination Survey, 1988-1994

Background: Inadequate vitamin A status has been a potential nutritional pr oblem for some segments of the US population, particularly children and the poor. Objective: We evaluated serum retinol concentration by using population-rep resentative data from 16 058 participants aged 4 to greater than or equal t o 90 y in the third National Health and Nutrition Examination Survey, 1988- 1994. Design: We used multivariate regression to examine the simultaneous associa tions of sociodemographic, biologic, and behavioral factors with serum reti nol concentration. Results: In children, serum retinol concentrations were greater with greate r age, body mass index, serum lipids, and the use of supplements containing vitamin A. In adults, male sex, serum lipids, alcohol consumption, and age were positively associated with serum retinol concentration in most racial /ethnic strata. Household income was not associated with serum retinol conc entration in children; associations were inconsistent in adults. The preval ence of serum retinol <0.70 <mu>mol/L was very low in all strata; the preva lence of serum retinol <1.05 <mu>mol/L was 16.7-33.9% in children aged 4-8 y and 3.6-14.2% in children aged 9-13 y,depending on sex and racial/ethnic group. The prevalence of serum retinol <1.05 <mu>mol/L was higher in non-Hi spanic black and Mexican American children than in non-Hispanic white child ren; these differences remained significant (P < 0.0001) after covariates w ere controlled for. Among adults, nonwhite women were significantly (P < 0. 0001) more likely than white women to have serum retinol <1.05 <mu>mol/L af ter covariates were controlled for. Conclusions: Clinically low serum retinol concentration is uncommon in US r esidents aged greater than or equal to4 y, although racial/ethnic and socio economic differences in serum retinol concentration still exist.