title: Long-term effects of leucine supplementation on body composition.
abstract: OBJECTIVE
  Leucine does not only serve as a substrate for protein synthesis but is also recognized as a potent signal nutrient that regulates protein metabolism. Accordingly, leucine supplementation has been suggested to develop muscle mass or prevent protein loss in several conditions characterized by muscle protein wasting. In the present review, we reported the recent results related to the effect of dietary leucine or leucine-rich amino acid mixture and proteins on whole body composition.
  
  
  RESULTS
  Although recent studies corroborate that increasing plasma leucine concentration generally induces an increase in muscle protein synthesis, long-term dietary leucine supplementation has been poorly investigated. Chronic free leucine supplementation alone did not improve lean body or muscle mass during resistance training or in elderly, whereas it was able to limit the weight loss induced by malnutrition. Contradictory data were also reported concerning the effect of leucine supplementation for weight management in obese patients. Leucine-rich amino acid mixture or proteins appeared more efficient than leucine alone to improve muscle mass and performance, suggesting the efficacy of leucine depends nevertheless on the presence of other amino acids.
  
  
  CONCLUSIONS
  Until now, there is no evidence that chronic leucine supplementation is efficient in promoting muscle mass or preventing protein loss during catabolic states. Further studies are required to determine the duration and nutritional conditions of long-term leucine supplementation and to establish whether such nutritional interventions can help to prevent or treat muscle loss in various pathological or physiological conditions.
authors.affiliation: INRA, UMR 1019 Nutrition Humaine, Saint Genès Champanelle, France.
authors.forename: Michèle
authors.initials: M
authors.lastname: Balage
authors.forename: Dominique
authors.initials: D
authors.lastname: Dardevet
mesh_terms: D000596:Amino Acids / Q000494:pharmacology; D001823:Body Composition / Q000187:drug effects*; D001825:Body Fluid Compartments / Q000378:metabolism*; D019587:Dietary Supplements; D006801:Humans; D007930:Leucine / Q000494:pharmacology*; D044342:Malnutrition / Q000503:physiopathology; D009124:Muscle Proteins / Q000378:metabolism*; D018482:Muscle, Skeletal / Q000187:drug effects* / Q000378:metabolism; D009765:Obesity / Q000188:drug therapy; D009929:Organ Size; D055070:Resistance Training; D015431:Weight Loss
chemical_list: D000596:Amino Acids; D009124:Muscle Proteins; D007930:Leucine