Vitamin A kinetics and utilization in Chinese vs US adults

Vitamin A (VA) kinetics, storage, and utilization were compared in well‐nourished Chinese (Wang Z et al., Br J Nutr ; 91 :–31, 2004) and US adults (Tang G et al., Am J Clin Nutr ; 78 :–66, 2003). [ 2 H 8 ]Retinyl acetate was orally administered (Chinese: n=15; 55 ± 4 y; mean ± SD and US: n=13; 60 ± 8 y), and plasma tracer and VA concentrations were measured from 3 h to 56 d. Data for plasma tracer vs time were fit to a 7‐compartment model using the Simulation, Analysis and Modeling software (WinSAAM). The average time for the appearance of labeled retinol bound to retinol‐binding protein in plasma was similar in both groups (~31 h). The plasma retinol pool was 3.34 ± 1.08 in Chinese vs 5.09 ± 1.11 μmol in US subjects (P<0.001); the model‐predicted total VA pool was 232 ± 116 and 1866 ± 1603 μmol (P<0.002), and disposal rate was 4.74 ± 2.55 and 9.89 ± 5.15 μmol/d (P<0.0025). Based on these kinetic parameters, Chinese had 54.0 ± 26.9 d of VA stores vs 267 ± 314 d in US adults (P<0.016). Our results indicate that VA stores and disposal rates differ in healthy, well‐nourished Chinese and US adults. (Chinese National Natural Science Foundation #30271121 and USDA #51000‐065)