Does supplementation with leucine-enriched protein alone and in combination with fish-oil-derived n–3 PUFA affect muscle mass, strength, physical performance, and muscle protein synthesis in well-nourished older adults? A randomized, double-blind, placebo-controlled trial
What this study found
Overall, leucine-enriched protein alone and with long-chain n-3 PUFAs did not improve appendicular lean mass, strength, physical performance, or integrated myofibrillar protein synthesis in these well-nourished older adults. Appendicular lean mass was unchanged versus control at postintervention: LEU-PRO 0.01 (-0.20, 0.22), P = 0.93; LEU-PRO+n-3 -0.08 (-0.29, 0.13), P = 0.44. Myofibrillar protein synthesis was also not different from control: LEU-PRO 0.14 %/d (95% CI: -0.25, 0.52; P = 0.46) and LEU-PRO+n-3 0.26 %/d (95% CI: -0.26, 0.78; P = 0.31). Isometric knee flexion peak torque was lower…
- Study & population
- Randomized, double-blind, placebo-controlled trial in community-dwelling adults aged 65 years and older at risk of sarcopenia.
- Intervention
- Participants in the active arms received a ready-to-drink, juice-based supplement twice daily for 24 weeks, before breakfast and before the second light meal.
- Key limitation
- The trial was relatively small and lasted only 24 weeks, which may limit power to detect modest changes in muscle outcomes.
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Open PDFOriginal abstract
ABSTRACT Background Leucine-enriched protein (LEU-PRO) and long-chain (LC) n–3 (ω–3) PUFAs have each been proposed to improve muscle mass and function in older adults, whereas their combination may be more effective than either alone. Objective The impact of LEU-PRO supplementation alone and combined with LC n–3 PUFAs on appendicular lean mass, strength, physical performance and myofibrillar protein synthesis (MyoPS) was investigated in older adults at risk of sarcopenia. Methods This 24-wk, 3-arm parallel, randomized, double-blind, placebo-controlled trial was conducted in 107 men and women aged ≥65 y with low muscle mass and/or strength. Twice daily, participants consumed a supplement containing either LEU-PRO (3 g leucine, 10 g protein; n = 38), LEU-PRO plus LC n–3 PUFAs (0.8 g EPA, 1.1 g DHA; LEU-PRO+n–3; n = 38), or an isoenergetic control (CON; n = 31). Appendicular lean mass, handgrip strength, leg strength, physical performance, and circulating metabolic and renal function markers were measured pre-, mid-, and postintervention. Integrated rates of MyoPS were assessed in a subcohort (n = 28). Results Neither LEU-PRO nor LEU-PRO+n–3 supplementation affected appendicular lean mass, handgrip strength, knee extension strength, physical performance or MyoPS. However, isometric knee flexion peak torque (treatment effect: −7.1 Nm; 95% CI: −12.5, −1.8 Nm; P < 0.01) was lower postsupplementation in LEU-PRO+n–3 compared with CON. Serum triacylglycerol and total adiponectin concentrations were lower, and HOMA-IR was higher, in LEU-PRO+n–3 compared with CON postsupplementation (all P < 0.05). Estimated glomerular filtration rate was higher and cystatin c was lower in LEU-PRO and LEU-PRO+n–3 postsupplementation compared with CON (all P < 0.05). Conclusions Contrary to our hypothesis, we did not observe a beneficial effect of LEU-PRO supplementation alone or combined with LC n–3 PUFA supplementation on appendicular lean mass, strength, physical performance or MyoPS in older adults at risk of sarcopenia. This trial was registered at clinicaltrials.gov as NCT03429491.