title: The effectiveness of leucine on muscle protein synthesis, lean body mass and leg lean mass accretion in older people: a systematic review and meta-analysis.
abstract: In the present study, we performed a meta-analysis to assess the ability of leucine supplementation to increase the muscle protein fraction synthetic rate and to augment lean body mass or leg lean mass in elderly patients. A literature search was conducted on Medline, Cochrane, EMBASE and Google Scholar databases up to 31 December 2013 for clinical trials that investigated the administration of leucine as a nutrient that affects muscle protein metabolism and muscle mass in elderly subjects. The included studies were randomised controlled trials. The primary outcome for the meta-analysis was the protein fractional synthetic rate. Secondary outcomes included lean body mass and leg lean mass. A total of nine studies were included in the meta-analysis. The results showed that the muscle protein fractional synthetic rate after intervention significantly increased in the leucine group compared with the control group (pooled standardised difference in mean changes 1·08, 95% CI 0·50, 1·67; P< 0·001). No difference was found between the groups in relation to lean body mass (pooled standardised difference in mean changes 0·18, 95% CI - 0·18, 0·54; P= 0·318) or leg lean mass (pooled standardised difference in mean changes 0·006, 95% CI - 0·32, 0·44; P= 0·756). These findings suggest that leucine supplementation is useful to address the age-related decline in muscle mass in elderly individuals, as it increases the muscle protein fractional synthetic rate.
authors.affiliation: Department of Geriatrics,School of Medicine, First Affiliated Hospital, Zhejiang University,79 Qingchun Road,Zhejiang Province, Hangzhou310003,People's Republic of China.
authors.forename: Zhe-rong
authors.initials: ZR
authors.lastname: Xu
authors.affiliation: Department of Geriatrics,School of Medicine, First Affiliated Hospital, Zhejiang University,79 Qingchun Road,Zhejiang Province, Hangzhou310003,People's Republic of China.
authors.forename: Zhong-ju
authors.initials: ZJ
authors.lastname: Tan
authors.affiliation: Department of Geriatrics,School of Medicine, First Affiliated Hospital, Zhejiang University,79 Qingchun Road,Zhejiang Province, Hangzhou310003,People's Republic of China.
authors.forename: Qin
authors.initials: Q
authors.lastname: Zhang
authors.affiliation: Department of Geriatrics,School of Medicine, First Affiliated Hospital, Zhejiang University,79 Qingchun Road,Zhejiang Province, Hangzhou310003,People's Republic of China.
authors.forename: Qi-feng
authors.initials: QF
authors.lastname: Gui
authors.affiliation: State Key Laboratory for Diagnosis and Treatment of Infectious Diseases, Department of Geriatrics,School of Medicine, First Affiliated Hospital, Zhejiang University,Hangzhou310003,People's Republic of China.
authors.forename: Yun-mei
authors.initials: YM
authors.lastname: Yang
mesh_terms: D000368:Aged; D001823:Body Composition; D015992:Body Mass Index; D016208:Databases, Factual; D019587:Dietary Supplements; D006801:Humans; D007866:Leg / Q000033:anatomy & histology; D007930:Leucine / Q000008:administration & dosage*; D009124:Muscle Proteins / Q000096:biosynthesis* / Q000187:drug effects*; D018482:Muscle, Skeletal / Q000187:drug effects / Q000378:metabolism; D016032:Randomized Controlled Trials as Topic
chemical_list: D009124:Muscle Proteins; D007930:Leucine
keywords: Dietary supplements; Elderly; Essential amino acids; Sarcopenia