Bioefficacy of β-carotene is improved in rats after solubilized as equimolar dose of β-carotene and lutein in phospholipid-mixed micelles

Abstract

beta-Carotene (BC) is a potent dietary source of vitamin A for populations at risk of vitamin A deficiency, yet its bioavailability is influenced by several factors such as dietary fat, carotenoids type, and other components. We hypothesize that type of micellar phospholipids influence bioefficacy of carotenoids and activity of carotenoid metabolizing enzymes. This study determined the BC bioefficacy in rats (n = 5/time point) after an equimolar dose of BC and lutein (Lut) solubilized in micelles containing either phosphatidylcholine (PC) or lysophosphatidylcholine (LPC), or no phospholipid (NoPL). Results show that no BC and Lut was detected in the plasma of rats at 0 hour, but after gavage, the mean (SD) area under the curve (AUC; in picomoles per milliliter) of plasma BC for 6 hours in PC, LPC, and NoPL groups were 1145 (132), 965 (199), and 2136 (112), respectively. The AUC value of plasma Lut in LPC group (183 +/- 23 pmol mL(-1) h(-1)) was higher than the other 2 groups. Similarly, liver BC and Lut levels in the LPC group were significantly higher than the other groups. The activity of BC 15,15'-monooxygenase in the intestinal mucosa of LPC and PC groups was higher than NoPL group. Plasma retinyl palmitate level in LPC (AUC, 647 +/- 89 pmol mL(-1) h(-1)) group was 2-fold higher than that of PC and NoPL groups. Results indicate that phospholipids enhanced the BC and Lut absorption. beta-Carotene uptake was not affected by Lut when given with micellar phospholipids, but reduced plasma Lut level was observed, which may be due to the conversion of absorbed Lut into its metabolites.