Abstract
Background/Objectives:Adequate protein intake is essential to retaining muscle and maintaining physical function, especially in the elderly, and L-Leucine has received attention as an essential amino acid (EAA) that enhances protein retention. The study's aim was to compare the efficacy of EAA mixtures on lean tissue mass (LTM) and functional performance (FP) in a healthy elderly population.Subjects/Methods:Thirty-six subjects (65–75 years) volunteered to receive capsules with EAAs (Groups A and B containing 20% and 40% L-Leucine, respectively) or placebo (lactose containing 0% L-Leucine, Group C) for 12 weeks. The daily amount ranged from 11 to 21 g (0.21 g/ kg/day) and was taken in two equal dosages alongside food, morning and evening. Main outcomes measured before and after intervention were LTM and FP (30-s arm-curl test; 30-s chair-stand test (30-CST); 6-min walk test (6-WT); and handgrip strength). Secondary outcomes included dietary intakes and physical activity.Results:Twenty-five subjects (11 male and 14 female) completed the study (Group A, n=8; Group B, n=8; Group C, n=9). Gains associated with medium effect sizes were noted in LTM (Group B, 1.1 ±1.1%, P=0.003) and FP (Group A in 30-CST (11.0±11.5%, P=0.02) and 6-WT (8.8±10.0%, P=0.02); Group B in 6-WT (5.8±6.6%, P=0.03) and a trend in 30-CST (13.2±16.0, P=0.06)). Significant differences between groups were not observed in secondary outcomes.Conclusions:Twice-daily supplementation of EAAs containing 20% or 40% L-Leucine improved aspects of functional status and at the higher level improved LTM. Further work to establish change in a larger sample and palatable supplemental format is now required.
Highlights
Sarcopenia is a complex and multifactorial syndrome associated with significant clinical, social and economic consequences
Over the 3 months, lean tissue mass (LTM) in Group B (modified essential amino acid (EAA) (40% leucine)) increased significantly compared with baseline (t(7) = −2.695, P = 0.031)
Significant differences were not observed between groups in the mean percentage changes in scores for the 30-s arm-curl test (F(2,22) = 1.776, P = 0.193), the 30-s chair-stand test (30-CST) (F(2,22) = 0.781, P = 0.470), the handgrip strength test (F(2,22) = 1.271, P = 0.300) and the 6-min walk test (6-WT) (F(2,22) = 2.225, P = 0.132)
Summary
Sarcopenia is a complex and multifactorial syndrome associated with significant clinical, social and economic consequences. Age-related sarcopenia has increased, and estimated prevalence rates are 13% in 60- to 70-year-old people and up to 50% in people aged 80 years and over.[1,2] there is no consensus for the definition of sarcopenia, the European Working Group on Sarcopenia in Older People (EWGSOP) has based the diagnostic criteria on the presence of low muscle mass, together with either low muscle strength or low physical performance.[3] Maintaining muscle mass and physical function is fundamental to promoting health and independence with age It has particular relevance for the prevention of falls, fracture and disability. Some of the most promising interventions have been nutritionally based.[4,5] Adequate protein intake is considered essential, and reports suggest that the current recommended daily allowance of 0.8 g/ kg/day is insufficient for the general population.[6,7] Instead, prophylactic amounts of 1.0–1.6 g/ kg/d and a larger proportion of high-quality protein in a meal (25–30 g) rather than increasing general total protein intake are proposed to meet the increased requirements of older people and to prevent sarcopenia.[8,9,10] protein intakes decrease with age owing to changes in taste, difficulties in chewing, swallowing and age-related anorexia,[11,12] presenting practical challenges for achievement of higher intakes
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