Compartmental models of vitamin A and beta-carotene metabolism in women.
We have developed compartmental models of vitamin A and beta-carotene (beta C) metabolism in women living under controlled conditions on diets with known concentrations of vitamins and carotenoids. Fourteen healthy adult women were given either retinyl-d4 acetate, or beta C-d8 before breakfast. Natural and stable-isotopes of retinol and beta C were collected in serum for up to 95 days or 20 days, respectively. Stable isotopes were separated from other components and measured by GC-MS or HPLC-UV. Preformed retinyl-d4 acetate metabolism in all women tested can be accurately described by a simple four-compartment model. However, the model did not fit one women initially, when she had marginal vitamin A status. We tested the hypothesis that dietary changes of beta C intake have important roles on the kinetics of vitamin A metabolism. Dietary changes of beta C intake did not influence the turnover rate of retinol in any compartment. However, it did result in changes in steady-state masses and residence times of retinol in several compartments. A working compartmental model for beta C metabolism was developed. The kinetics of retinol-d4 formed from beta C is more complicated than the pre-formed retinol-d4. Results suggest that beta C-d8 readily converts into retinol-d4 with high inter-individual variability.
Western Human Nutrition Research Center, U.S. Department of Agriculture, Presidio of San Francisco, CA 94129, USA.
B J
BJ
Burri
J Y
JY
Park
D000328:Adult; D016588:Anticarcinogenic Agents / Q000097:blood / Q000378:metabolism; D002851:Chromatography, High Pressure Liquid; D003198:Computer Simulation; D003903:Deuterium / Q000032:analysis; D004224:Diterpenes; D005260:Female; D008401:Gas Chromatography-Mass Spectrometry; D006801:Humans; D007700:Kinetics; D008954:Models, Biological; D000084562:Retinyl Esters; D014801:Vitamin A / Q000031:analogs & derivatives / Q000097:blood / Q000378:metabolism*; D019207:beta Carotene / Q000097:blood / Q000378:metabolism*
D016588:Anticarcinogenic Agents; D004224:Diterpenes; D000084562:Retinyl Esters; D019207:beta Carotene; D014801:Vitamin A; C009166:retinol acetate; D003903:Deuterium