Am J Clin Nutr. 2008 Apr;87(4):817-23.Click here to read Links
Parallel activation of de novo lipogenesis and stearoyl-CoA desaturase activity after 3 d of high-carbohydrate feeding.
Chong MF, Hodson L, Bickerton AS, Roberts R, Neville M, Karpe F, Frayn KN, Fielding BA.
Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Oxford, United Kingdom.
BACKGROUND: High-carbohydrate (HC) diets increase de novo lipogenesis (DNL), but effects on stearoyl-CoA desaturase (SCD) are not so well studied. OBJECTIVE: The objective was to investigate DNL and SCD in liver and adipose tissue by using fatty acid ratios after short-term dietary intervention. DESIGN: Eight subjects consumed isoenergetic 3-d HC (10% fat; 75% carbohydrates) or higher fat (HF; 40% fat; 45% carbohydrates) diets (sugar to starch ratio: 60:40 for both) in a crossover study. Blood was taken from an artery and a vein draining subcutaneous adipose tissue. DNL and SCD activity were investigated by using the ratios of 16:0 to 18:2n-6 and of 16:1n-7 to 16:0, respectively. A test meal, including [U-(13)C]palmitate was given to trace dietary fatty acid incorporation into VLDL-triacylglycerol (TG). The conversion of intravenously infused [(2)H(2)]palmitic acid to [(2)H(2)]palmitoleic acid in VLDL-TG was quantified as a specific marker of hepatic SCD activity. RESULTS: The VLDL-TG 16:0/18:2n-6 ratio, which reflects hepatic DNL, was greater after the HC diet than after the HF diet (P = 0.02). With the HC diet, increased plasma TG concentrations correlated with 16:0/18:2n-6 ratios (r = 0.76, P = 0.028). Plasma VLDL-TG and adipose venous nonesterified fatty acid (NEFA) 16:1n-7/16:0 ratios were higher after the HC diet (fasting: P = 0.01 and P = 0.05, respectively; postprandial: P = 0.03 and P = 0.05, respectively). Changes in fasting VLDL-TG 16:0/18:2n-6 and 16:1n-7/16:0 ratios were associated (P = 0.06). The contribution of total fatty acids from splanchnic sources (including DNL) was higher after the HC diet (P = 0.02). Expression of lipogenic genes in subcutaneous adipose tissue was not significantly affected by diet. CONCLUSION: Parallel activation of DNL and SCD was found after a short period of HC feeding.