Effects of choline deficiency and phosphatidylcholine on fat absorption in rats

Transfer of lipid to the lymph by the intestine was studied in rats fed on choline-deficient or choline-supplemented diet for 2 weeks. In choline-deficient rats, lymph output was reduced. Choline deficiency impaired the incorporation of glycerol tri[1-14C]oleate into triglyceride in the lymph. The triglyceride level in lymph lipoproteins was lower in choline-deficient rats than in controls. Ultrastructural studies suggested that impaired release of lipoproteins was responsible for accumulation of fat in intestinal absorptive cells. These defects are probably related to changes in the membrane system of the intestine and to a failure in lipid droplet movement within absorptive cells, resulting from alterations in the microfilaments. Oral administration of phosphatidylcholine to rats on choline-deficient diet rapidly improved the decreased lymph output and the impaired incorporation of glycerol tri[1-14C]oleate into triglyceride and reduced fat deposition in intestinal epithelial cells. In conclusion, phospholipids such as choline are confirmed as being extremely important in the absorption of fat by the possible mechanism of fat transport across the membrane.