STUDIES ON THE BIOCONVERSION OF BETA-CAROTENE TO ACTIVE VITAMIN-A IN UNDERPRIVILEGED GUATEMALAN CHILDREN

The mechanism by which the rate of beta-carotene conversion to active vitamin A in the enterocyte is poorly under-stood. It is postulated th at body vitamin A status plays a very important role. Until recently, it has riot been possible to detect and quantify the product of beta-c arotene bioconversion, i.e., retinal, in the grit, and retinyl ester, in the circulation. This study aimed at confirming that a rise in plas ma retinyl palmitate concentration would occur after administration of beta-carotene to underprivileged Guatemalan schoolchildren. Twenty ru ral children, aged 7 to II years, received 30 mg of pure, crystalline beta-carotene in oral capsules in the fasting state. Thirteen peri-urb an poor children participated as controls; each received capsules of c ellulose. Standard meals with low vitamin A levels were served during the observation period. Plasma levels of beta-carotene, retinol, and r etinyl palmitate were determined by HPLC at baseline, 2 hr, and 24 hr after Ingestion of capsules. Anthropometric and biochemical characteri stics were similar in both groups at baseline. An average increase of 0.15 +/- 0.05 mu mol/L in retinyl esters was observed in the supplemen ted group at 2 hr, with a return to baseline levels at 24 hr; whereas in the control group no retinyl esters were detected at all at any tim e. A tendency of a greater retinyl ester response with a lower-baselin e circulating retinol level was observed. This is rite first instance in which beta-carotene bioconversion to retinyl palmitate has been qua ntified in children. We propose that the rise in retinyl esters after oral administration of beta-carotene could be used to examine the fact ors that influence the rate of bioconversion of beta-carotene to activ e vitamin A. (C) Elsevier Science Inc. 1997.