Studies on the bioconversion of β-carotene to active vitamin A in underprivileged Guatemalan children

Abstract The mechanism by which the rate of β-carotene conversion to active vitamin A in the enterocyte is poorly understood. It is postulated that body vitamin A status plays a very important role. Unitl recently, it has not been possible to detect and quantify the product of β-carotene bioconversion, i.e., retinal, in the gut, and retinyl ester, in the circulation. This study aimed at confirming that a rise in plasma retinyl palmitate concentration would occur after administration of β-carotene to underprivileged Guatemalan schoolchildren. Twenty rural children, aged 7 to 11 years, received 30 mg of pure, crystalline β-carotene in oral capsules in the fasting state. Thirteen peri-urban poor children participated as controls; each received capsules of cellulose. Standard meals with low vitamin A levels were served during the observation period. Plasma levels of β-carotene, retinol, and retinyl palmitate were determined by HPLC at baseline, 2 hr, and 24 hr after ingestion of capsules. Anthropometric and biochemical characteristics were similar in both groups at baseline. An average increase of 0.15 ± 0.05 μmol/L in retinyl esters was observed in the supplemented 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 time. A tendency of a greater retinyl ester response with a lower baseline circulating retinol level was observed. This is the first instance in which β-carotene bioconversion to retinyl palmitate has been quantified in children. We propose that the rise in retinyl esters after oral administration of β-carotene could be used to examine the factors that influence the rate of bioconversion of β-carotene to active vitamin A.