Dietary fats with increased ratio of unsaturated to saturated fatty acids enhance absorption of carotenoid and vitamin E by increasing both efficiency of micellarization and lipoprotein secretion.

Abstract

Although it is well established that dietary fat promotes the bioavailability of carotenoids and other dietary lipophiles, insights regarding the effects of different lipid sources on processes associated with absorption of these plant compounds remain unclear. We previously reported that triacylglycerides (TG) with higher ratios of unsaturated to saturated fatty acids (FA) increased the efficiency of micellarization of carotenes. Here we examined the influence of FA composition of TG on uptake of β‐carotene (BC), lutein (Lut) and αTC and their basolateral secretion in chylomicrons by Caco‐2 cells. Differentiated Caco‐2 cells were pretreated 4h/d for 4d by apical exposure of cultures to mixtures of saturated, mono‐unsaturated and poly‐unsaturated FA similar to those present in butter (76:24:0) and olive(12:74:14), canola(9:56:35) and soybean oil (16:24:60). On the following day, micelles containing βC, Lut and αTC were included along with the FA mixtures in apical medium. Uptake of test compounds was unaffected by micelle FA composition, whereas micelles rich in unsaturated FA strongly promoted basolateral secretion of BC, Lut and αTC. The number and size of chylomicrons (total TG and TG to apoB48/100 ratio) also were significantly increased by chronic exposure to micelles with FA composition mimicking vegetable oils. Therefore, it appears that ingestion of TG enriched in with unsaturated FA enhances bioavailability of carotenoids and αTC by increasing micellarization during digestion and transepithelial transport by absorptive epithelial cells. Supported by USDA NRI Grant # 2007‐02313 and OARDC.