Low and high responders to pharmacological doses of β-carotene: proportion in the population, mechanisms involved and consequences on β-carotene metabolism

Abstract

The aim of this study was to assess the interindividual variability of chylomicron β-carotene response to a pharmacological load of β-carotene in the population, to identify the mechanisms responsible for this variability, and to evaluate its consequences on β-carotene status and metabolism. The variability, as estimated by the 3-h chylomicron β-carotene response to 120 mg β-carotene in 79 healthy male volunteers, was high (CV = 61“%), but it was unimodal and all the subjects had detectable chylomicron β-carotene. In 16 subjects randomly selected among the 79, the interindividual variability of the triglyceride-adjusted chylomicron (β-carotene + retinyl palmitate) response (0–12.5 h area under the curve) was high (CV = 54”%), suggesting that there is a high interindividual variability in the efficiency of intestinal absorption of β-carotene. The chylomicron β-carotene response was correlated (r = 0.50, P < 0.05) with the chylomicron triglyceride response. The β-carotene status, as assessed by β-carotene concentration in buccal mucosal cells, was correlated (r = 0.73, P < 0.05) with the triglyceride-adjusted chylomicron β-carotene response, i.e., with the ability to respond to β-carotene. The triglyceride-adjusted chylomicron retinyl-palmitate response was correlated (r = 0.55, P < 0.05) with the triglyceride-adjusted chylomicron β-carotene response. Plasma all-trans retinoic acid slightly, but significantly, increased (+40“%) 3 h after the β-carotene load, but this increase was not related to the triglyceride-adjusted β-carotene response. In conclusion, the ability to respond to β-carotene is highly variable, but there is probably a very small proportion of true non-responders to pharmacological doses of β-carotene in the healthy population. This variability is apparently mainly due to interindividual differences in the efficiency of intestinal absorption of β-carotene and in chylomicron metabolism. The ability to respond to β-carotene can affect the β-carotene status and the provitamin A activity of β-carotene, but it has apparently no effect on the amount of retinoic acid appearing in the plasma after the ingestion of a pharmacological dose of β-carotene. —Borel, P., P. Grolier, N. Mekki, Y. Boirie, Y. Rochette, B. Le Roy, M. C. Alexandre-Gouabau, D. Lairon, and V. Azais-Braesco. Low and high responders to pharmacological doses of β-carotene: proportion in the population, mechanisms involved, and consequences on β-carotene metabolism. J. Lipid Res. 1998. 39: 2250–2260.