Double-blind, placebo-controlled pilot trial of L-Leucine-enriched amino-acid mixtures on body composition and physical performance in men and women aged 65-75 years.
Level 2 - randomized trial
Double-blind, placebo-controlled randomized trial
PubMed 26081485 · doi:10.1038/ejcn.2015.91
What was done
Thirty-six healthy men and women aged 65–75 years were randomized in a double-blind, placebo-controlled pilot trial to receive capsules of essential amino acids (EAAs) containing 20% L-leucine (Group A), 40% L-leucine (Group B), or a lactose placebo (Group C) for 12 weeks. Supplements were taken twice daily with meals at a total dose of 0.21 g/kg/day (11–21 g/day). The primary outcomes were changes in lean tissue mass and functional performance tests (30-second arm curl, 30-second chair stand, 6-minute walk, and handgrip strength). Secondary outcomes were dietary intake and physical activity.
What was found
Twenty-five participants completed the study (Group A: n=8, Group B: n=8, Group C: n=9). The 40% L-leucine group showed an increase in lean tissue mass (1.1 ± 1.1%, P = 0.003). Functional improvements included 6-minute walk distance in Group A (8.8 ± 10.0%, P = 0.02) and Group B (5.8 ± 6.6%, P = 0.03), and 30-second chair-stand repetitions in Group A (11.0 ± 11.5%, P = 0.02) with a trend in Group B (13.2 ± 16.0, P = 0.06). Secondary outcomes showed no significant between-group differences.
Why it matters
This pilot trial indicates that leucine-enriched essential amino acid mixtures can modestly benefit muscle mass and functional mobility in healthy older adults.
Limits
The sample size was very small (n=25 completed out of 36 enrolled, reflecting a ~31% dropout rate). The study was limited to healthy older adults aged 65–75 over a short 12-week intervention, and the abstract does not provide complete between-group statistical comparisons for all functional measures.
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- partial In older adults aged 75 and older who do not strength train, essential amino acid supplementation significantly improves walking speed, walking endurance, and sit-to-stand time.