Metabolic fate of an oral long-chain triglyceride load in humans.
To determine the steps involved in the metabolism of ingested triglycerides (TG), 10 healthy women were studied during 6 h after ingestion of 30 g olive oil labeled with [1,1,1-13C3] triolein. The appearance of 13C was followed in chylomicron-TG (CM-TG), nonesterified fatty acid (NEFA), very low-density lipoprotein (VLDL)-TG, and in expired gas. Indirect calorimetry was used to determine total lipid oxidation. After 90 min, labeling was higher in CM-TG than in NEFA or VLDL. At 180 min, a plateau of enrichment was obtained for CM-TG and NEFA, demonstrating the entry of exogenous lipids in the NEFA pool. After 300 min, a plateau was observed for VLDL-TG with levels of enrichment (0.38 +/- 0.04%) similar to those observed for NEFA (0.36 +/- 0.03%), suggesting a precursor-product relationship. Only 19 +/- 2% of the load was oxidized. From 300 to 360 min, 70% of total lipid oxidation was from exogenous TG. We conclude that, after ingestion of a lipid load, a cycle of fatty acids-TG occurs from CM to NEFA and from NEFA to VLDL. Furthermore, this lipid load has a sparing effect on endogenous lipid stores.
Binnert
C
C
Faculte de Medecine Alexis Carrel, Institut National de la Sante et de la Recherche Medicale, Lyon, France.
Pachiaudi
C
C
Beylot
M
M
Croset
M
M
Cohen
R
R
Riou
J P
JP
Laville
M
M
D000328:Adult; D002247:Carbon Isotopes; D002914:Chylomicrons / Q000097:blood; D004041:Dietary Fats; D005230:Fatty Acids, Nonesterified / Q000097:blood; D005260:Female; D006801:Humans; D007657:Ketone Bodies / Q000097:blood; D008079:Lipoproteins, VLDL / Q000097:blood; D000069463:Olive Oil; D010938:Plant Oils; D013997:Time Factors; D014280:Triglycerides / Q000097:blood*; D014304:Triolein / Q000378:metabolism*
D002247:Carbon Isotopes; D002914:Chylomicrons; D004041:Dietary Fats; D005230:Fatty Acids, Nonesterified; D007657:Ketone Bodies; D008079:Lipoproteins, VLDL; D000069463:Olive Oil; D010938:Plant Oils; D014280:Triglycerides; D014304:Triolein