Reduced oxidation of dietary fat after a short term high-carbohydrate diet

• Published in: The American journal of clinical nutrition 2008-04, Vol.87 (4), p.824-831
• Main Authors: Roberts, Rachel, Bickerton, Alex S, Fielding, Barbara A, Blaak, Ellen E, Wagenmakers, Anton J, Chong, Mary F.F, Gilbert, Marjorie, Karpe, Fredrik, Frayn, Keith N
• Format: Article
• Language: English
• Subjects: acute effects; Adaptation, Physiological; Adult; Biological and medical sciences; blood lipids; Breath Tests; Carbohydrates; carbon; Carbon Isotopes; Cross-Over Studies; Deuterium; Diet; Dietary Carbohydrates - administration & dosage; Dietary Carbohydrates - pharmacology; dietary fat; Dietary Fats - administration & dosage; Dietary Fats - metabolism; Dietary Fats - pharmacology; Dose-Response Relationship, Drug; Fasting - blood; fatty acids; Fatty Acids - metabolism; Feeding. Feeding behavior; Female; Fundamental and applied biological sciences. Psychology; high carbohydrate diet; Humans; Hypertriglyceridemia - etiology; isotope labeling; lipid metabolism; lipid peroxidation; Lipoproteins, VLDL - blood; Liver - metabolism; Male; men; metabolic studies; Middle Aged; Muscle, Skeletal - metabolism; Oils & fats; Oxidation; Oxidation-Reduction; Postprandial Period; stable isotopes; Studies; triacylglycerols; Triglycerides - blood; Vertebrates: anatomy and physiology, studies on body, several organs or systems; very low density lipoprotein; women
• ISSN: 0002-9165; 1938-3207
• DOI: 10.1093/ajcn/87.4.824

BACKGROUND:Short-term high-carbohydrate (HC) diets induce metabolic alterations, including hypertriacylglycerolemia, in both the fasting and postprandial states. The underlying tissue-specific alterations in fatty acid metabolism are not well understood. OBJECTIVE:We investigated alterations in exogenous and endogenous fatty acid metabolism by using stable isotope tracers to label meal triacylglycerol and plasma fatty acids. DESIGN:Eight healthy subjects consumed isocaloric diets containing a high percentage of energy from carbohydrates or a higher percentage of energy from fat for 3 d in a randomized crossover dietary intervention study. A test meal containing [U-¹³C]palmitate was combined with intravenous infusion of [²H₂]palmitate to label plasma fatty acids and VLDL triacylglycerol. Blood and breath samples were taken before the meal and for 6 h postprandially. Blood samples were drawn from the femoral artery and from veins draining subcutaneous adipose tissue and forearm muscle for monitoring of tissue-specific metabolic substrate partitioning. RESULTS:Systemic triacylglycerol concentrations were increased in both fasting (P = 0.02) and postprandial (P = 0.02) periods, and a greater amount of infused labeled fatty acid appeared in VLDL triacylglycerol after the HC diet than after the higher-fat diet (P = 0.05). Significantly less ¹³CO₂ was exhaled after the HC diet (P = 0.04) and significantly less production of ¹³CO₂ was seen across forearm muscle (P = 0.04). Systemic 3-hydroxybutyrate was significantly lower, postprandially, after the HC diet (P = 0.02). CONCLUSION:Metabolic alterations suggestive of repartitioning of fatty acids away from oxidation toward esterification in both liver and muscle occur in response to short-term adaptation to a HC diet.