UPTAKE AND METABOLISM OF STRUCTURED TRIGLYCERIDE BY CACO-2 CELLS - REVERSAL OF ESSENTIAL FATTY-ACID DEFICIENCY

Structured lipids have been proposed as efficient vehicles for the sup plementation of essential fatty acids (EFA) to patients with malabsorp tion. We investigated how a novel structured triglyceride (STG), conta ining purely octanoic acid in the sn-1/sn-3 and [C-14]linoleic acid in the sn-2 positions, was incorporated into different lipid classes in Caco-2 cells. We also evaluated the contribution of gastric Lipase in the uptake and metabolism of [C-14]linoleic acid from the STG. We furt hermore determined the potential of the STG to correct EFA deficiency induced in Caco-2 cells. The absorption of STG by Caco-2 cells was sig nificantly greater compared with that of triolein. The addition of hum an gastric lipase significantly enhanced cellular uptake of the labele d substrate, reflecting the stereoselectivity of gastric lipase to hyd rolyze medium chain FA. Analysis of the intracellular lipids synthesiz ed revealed a predominance of phospholipids-monoglycerides. Most of th e radioactivity in the lipoproteins isolated from Caco-2 cells was rec overed in TG-rich lipoproteins (45%) and to a lesser extent in the hig h-density lipoprotein (36%) and low-density Lipoprotein (17%) fraction s. The administration of STG to Caco-2 cells rendered EFA deficient pr oduced a marked increase of the cellular level of linoleic and arachid onic acids. This resulted in a lower ratio of 20:3(n-9) to 20:4(n-6), reflecting the correction of EFA deficiency in Caco-2 cells. Our data demonstrate that STG, in the presence of gastric Lipase, have benefici al effects on lipid incorporation, lipoprotein production, and EFA sta tus, utilizing Caco-2 cells as a model of EFA deficiency.