The absorption of fats studied in a patient with chyluria. II. Palmitic and oleic acids.

The transport route for saturated and unsaturated long chain fatty acids has been well established in animal experiments. Only small amounts of these acids are absorbed via the portal vein, with the major part traveling via the lymphatics. Oleic and linoleic acids (1, 2) are absorbed similarly to long chain saturated acids (2, 3), irrespective of the form in which they are presented for absorption (i.e. as free acids or as triglyceride esters). Since the classical work by Munk and Rosenstein (4) on a patient with a lymphatic fistula, few definitive studies of this aspect of fat absorption have been made in human beings. Fernandes et al. (5) recently carried out studies of fat absorption in a child with chylothorax and compared the component fatty acids of the dietary and chyle fats. In the case of the long chain fatty acids the compositions of the two fats closely resembled each other, except that there was a lower content of stearic acid in the chyle as a result of less complete absorption. Since these authors did not use labeled compounds in their investigation, the incorporation of fatty acids in the diet into the different lipide classes of the lymph could not be followed. The present study of the absorption of labeled palmitic and oleic acids in man was made possible by the unusual experimental opportunity presented by the clinical condition known as chyluria. The subject of this study was a 52 year-old Puerto Rican woman in whom an anomolous connection existed between the intestinal lymphatics and the left renal pelvis. The clinical aspects of this case have been presented elsewhere (6), together with a number of quantitative studies of fat absorption. In the present investigation labeled acids were fed to the patient in corn oil as free acids or as triglyceride esters. Absorption of t,he tagged acids was complete. In all experiments these acids were incorporated mainly into the lymph triglycerides and only to a minor degree in the phospholipides, irrespective of the form in which they were fed. A very small amount of the isotopic acids wa,s found in the nonesterified fatty acids of the chyle.