Influence of phospholipids on beta-carotene absorption and conversion into vitamin A in rats.

This study determines the effect of lysophosphatidylcholine (lysoPC) and phosphatidylcholine (PC) in mixed micelles on beta-carotene and retinyl palmitate levels in rats in order to delineate the role of micellar phospholipids in the intestinal uptake of beta-carotene and its conversion into vitamin A. The rats were fed a single dose of beta-carotene solubilized in lysoPC (LPC group), PC (PC group) or no phospholipids (NoPL, control group) in micellar form. The level of beta-carotene and retinyl palmitate in plasma and beta-carotene in liver was analyzed by HPLC after 1, 2, 3, 6 and 9 h of feeding. The postprandial levels of beta-carotene in plasma (599.9 pmol/mL, Area Under Curve (AUC)) and in liver (1,161.3 pmol/g) were significantly (p<0.05) higher in the LPC group compared with its level in plasma (207.2 pmol/mL) and in liver (616.5 pmol/g) of the PC group and in plasma (119.1 pmol/mL) and in liver (626.2 pmol/g) of the NoPL group. No difference was seen between the PC and NoPL groups. The results demonstrate that beta-carotene absorption and its accumulation in plasma and liver were unaffected by PC compared with NoPL, while lysoPC not only enhanced its accumulation but also increased cleavage of intestinally absorbed beta-carotene into vitamin A as the AUC of plasma BC was higher and the AUC of retinyl palmitate in plasma of the lysoPC group was significantly higher than those of the other two groups. The results suggest that the luminal hydrolysis of PC to lysoPC is necessary for intestinal uptake of beta-carotene solubilized in mixed micelles.