Effects of supplementation with essential amino acids on intrahepatic lipid concentrations during fructose overfeeding in humans

Background: A high dietary protein intake has been shown to blunt the deposition of intrahepatic lipids in high-fat- and high-carbohydrate-fed rodents and humans. Objective: The aim of this study was to evaluate the effect of essential amino acid supplementation on the increase in hepatic fat content induced by a high-fructose diet in healthy subjects. Design: Nine healthy male volunteers were studied on 3 occasions in a randomized, crossover design after 6 d of dietary intervention. Dietary conditions consisted of a weight-maintenance balanced diet (control) or the same balanced diet supplemented with 3 g fructose $ kg 21 $ d 21 and 6.77 g of a mixture of 5 essential amino acids 3 times/d (leucine, isoleucine, valine, lysine, and threonine) (HFrAA) or with 3 g fructose $ kg 21 $ d 21 and a maltodextrin placebo 3 times/d (HFr); there was a washout period of 4 to 10 wk between each condition. For each condition, the intrahepatocellular lipid (IHCL) concentration, VLDL-triglyceride concentration, and VLDL-[ 13 C]palmitate production were measured after oral loading with [ 13 C]fructose. Results: HFr increased the IHCL content (1.27 6 0.31 compared with 2.74 6 0.55 vol %; P , 0.05) and VLDL-triglyceride (0.55 6 0.06 compared with 1.40 6 0.15 mmol/L; P , 0.05). HFr also enhanced VLDL-[ 13 C]palmitate production. HFrAA significantly