Effect of carbohydrate intake on de novo lipogenesis in human adipose tissue.
Rates of synthesis, from [14C]glucose, of fatty acids (de novo lipogenesis) and glycerol (triglyceride synthesis) were measured in biopsies of adipose tissue from nutritionally depleted patients given low- or high-carbohydrate intravenous nutrition. Simultaneously, energy expenditure and whole-body lipogenesis were measured by indirect calorimetry. Rates of whole-body lipogenesis were zero on the low-carbohydrate diet and averaged 1.6 g.kg-1.day-1 on the high-carbohydrate diet. In vitro rates of triglyceride synthesis increased 3-fold going from the low to the high intake; rates of fatty acid synthesis increased approximately 80-fold. In vitro, lipogenesis accounted for less than 0.1% of triglyceride synthesis on the low intake and 4% on the high intake. On the high-carbohydrate intake, in vitro rates of triglyceride synthesis accounted for 61% of the rates of unidirectional triglyceride synthesis measured by indirect calorimetry. In vitro rates of lipogenesis accounted for 7% of whole-body lipogenesis. Discrepancies between in vitro rates of fatty acid synthesis from glucose, compared with acetate and citrate, as reported by others, suggest that in depleted patients on hypercaloric high-carbohydrate diets, adipose tissue may account for up to 40% of whole-body lipogenesis.
D000273:Adipose Tissue / Q000378:metabolism*; D000328:Adult; D000368:Aged; D002151:Calorimetry; D004040:Dietary Carbohydrates / Q000378:metabolism*; D004734:Energy Metabolism; D005227:Fatty Acids / Q000378:metabolism; D005990:Glycerol / Q000378:metabolism; D006801:Humans; D066298:In Vitro Techniques; D008055:Lipids / Q000096:biosynthesis*; D008875:Middle Aged; D009748:Nutrition Disorders / Q000378:metabolism*; D010289:Parenteral Nutrition, Total; D014280:Triglycerides / Q000096:biosynthesis
D004040:Dietary Carbohydrates; D005227:Fatty Acids; D008055:Lipids; D014280:Triglycerides; D005990:Glycerol