The effects of dietary phospholipids enriched with phosphatidylethanolamine on bile and red cell membrane lipids in humans |
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Authors: | Ronit Pakula Fred M Konikoff Moshe Rubin Yehuda Ringel Yochanan Peled Aliza Tietz Tuvia Gilat |
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Affiliation: | (1) Sackler Faculty of Medicine, Tel-Aviv University, Ramat Aviv, Petah-Tikva, Israel;(2) Department of Surgery “A”, Beilinson Medical Center, Petah-Tikva, Israel;(3) Felsenstein Medical Research Center, Petah-Tikva, Israel;(4) Department of Biochemistry, Tel-Aviv University, Ramat Aviv, Israel;(5) Department of Gastroenterology, Tel Aviv Medical Center, 6 Weizman St., 64239 Tel Aviv, Israel |
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Abstract: | The role of phospholipids in biliary cholesterol solubilization and crystallization has only recently begun to be appreciated.
Phospholipid vesicles are believed to be the metastable carrier from which cholesterol nucleates. Cholesterol crystallization
is influenced by the phospholipid species in bile. Feeding rats and hamsters with diets enriched in phospholipids or their
precursors, especially ethanolamine, resulted in reduced cholesterol saturation of bile. Although whole phospholipids are
normal dietary constituents, the effects and safety of phospholipid components have not been tested in humans. In the present
study, we have evaluated the effects of a dietary phospholipid mixture, enriched with phosphatidylethanolamine, on human bile
and red blood cell membrane lipid composition. Five ambulatory volunteers having a chronic indwelling T-tube, with an intact
enterohepatic circulation, were investigated. Thirty-six grams of phospholipids (54% phosphatidylethanolamine, 54% linoleyl
acyl chains) were added to their daily diet for fourteen days. Biliary nucleation time, cholesterol carriers, as well as plasma,
red blood cell membrane, and bile lipid compositions, were monitored. Following phospholipid supplementation, the proportion
of linoleyl chains (18:2) in biliary phospholipids increased significantly from 31.1±1.2 to 37.7±5.3%, while that of oleyl
chains (18:1) decreased from 11.4±1.6 to 9.6±1.1%. These changes were accompanied by an increase of linoleate and its metabolite,
arachidonate, in red cell membranes. Phospholipid feeding did not cause any side effects, and no significant changes in biliary
nucleation time, cholesterol, phospholipid, or bile salt concentrations, or in the distribution of cholesterol within micelles
or vesicles. We conclude that phospholipid feeding is safe, and can be effective as a vehicle for lecithin fatty acyl chain
modulation of bile and lipid membranes. These findings may provide a basis for a controlled modulation of biliary phospholipids
to increase cholesterol solubility in bile. |
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