Objective: Multiple post-digestion factors can attenuate serum carotenoid concentrations. Longitudinal studies have shown an inverse relationship between serum carotenoids and body mass index (BMI); however, the relationship between β-carotene and BMI in population samples is not well understood. Our primary objective was to determine the association between reported dietary β-carotene intakes and serum β- carotene concentrations, controlling for BMI, age, sex, and ethnicity.

Methods: Data were obtained from NHANES 2003-2006 using multistage probability sampling, including dietary intake and serum β-carotene concentrations for 9,182 male and non-pregnant female participants aged 20-85 years in the United States. The distributions of reported dietary and serum β-carotene concentrations were skewed, therefore log transformed values were used for analysis. Multiple linear regression estimated serum carotenoid concentrations based on reported dietary intake of carotenoids adjusted for BMI, age, sex, and ethnicity.

Results: The prevalence of low serum β-carotene concentrations (<50 μg/dL) was 86.7%, and prevalence of obesity was 32.6%. Mean and standard deviation (SD) was 2.51±0.85 μg/dL for log (serum β-carotene) and 6.52±1.48 μg for log(reported dietary β- carotene). Mean and SD for BMI was 28.27±6.55 kg/m2. Serum β-carotene concentrations were inversely associated with BMI (r= - 0.19, p<0.0001) and weakly associated with reported dietary β-carotene intake (r=-0.04, p<0.0002). Mean untransformed serum β-carotene was significantly lower in obese subjects compared to normal weight subjects (14.39 ± 14.87 μg/dL versus 21.80 ± 24.46 μg/dL, p<0.001). Serum β-carotene concentrations decreased by 0.22 μg/dL for each standard deviation increase in BMI and increased by 0.22 μg/dL for each standard deviation increase in reported dietary βcarotene.

Conclusions: There was a weak association present between reported dietary β- carotene intakes and serum β-carotene concentrations. A moderate association was present between serum βcarotene and BMI, suggesting individuals with an increased BMI may have a greater risk of low serum β-carotene concentrations despite adequate dietary intake of β-carotene.