Dietary phospholipids and intestinal cholesterol absorption

Abstract

Experiments carried out with cultured cells and in experimental animals have consistently shown that phospholipids (PLs) can inhibit intestinal cholesterol absorption. Limited evidence from clinical studies suggests that dietary PL supplementation has a similar effect in man. A number of biological mechanisms have been proposed in order to explain how PL in the gut lumen is able to affect cholesterol uptake by the gut mucosa. Further research is however required to establish whether the ability of PLs to inhibit cholesterol absorption is of therapeutic benefit.

Keywords: cardiovascular disease; cholesterol; intestine; micelle; phosphatidylcholine; phosphatidylethanolamine; phospholipid; sphingomyelin.

Figure 1

Effect of liver lecithin on intestinal uptake of micellar cholesterol. Everted rat gut sacs were incubated at 37 °C for 1 hr in 25ml micellar solution containing 0.15 mM cholesterol and 4.8 mM bile salt with various amounts of added lecithin. Orange ring symbol represents data obtained with egg lecithin replacing liver lecithin. Each point is the mean of 4–8 experiments. Vertical bars are SE (reproduced from ref. [18]).

Figure 2

Effect of dietary lecithin (polyenylphosphatidylcholine, 10 grams/day) on cholesterol absorption in hypertriglyceridemic patients. Data are shown for individual patients. During Period I patients were given 7 grams/day of safflower oil and during Period 2 they were given 10 grams/day lecithin (one dose each morning). The amount and composition of fatty acids was equivalent for the two treatments. Cholesterol absorption was measured after two or three weeks by monitoring the ratio of [¹⁴C] cholesterol to [³H] b-sitosterol in stools of patients given oral radioactive sterols. Mean cholesterol absorption (shown by the dark horizontal line) during the control period was 42 ± 2% and during the lecithin treatment period was 36 ± 2%. (reproduced from ref. [30])