Objectives: To test the effects of bolus supplementation of branched-chain amino acids (BCAA) on skeletal muscle mass, strength, and function in patients with rheumatic disorders taking glucocorticoid (GC).
Methods: Patients with rheumatic disorders treated with prednisolone (≥10 mg/day) were randomized to ingest additional daily 12 g of BCAA (n = 9) or not (n = 9) for 12 weeks. At baseline, and 4, 8, and 12 weeks, they underwent bioelectrical impedance analysis, muscle strength and functional tests, and computed tomography analysis for cross-sectional area of mid-thigh muscle.
Results: Disease activities of the patients were well controlled and daily GC dose was similarly reduced in both groups. Limb muscle mass was recovered in both groups. Whole-body muscle mass and muscle strength and functional mobility were increased only in BCAA (+) group. The effects of BCAA supplementation on recovering skeletal muscle mass were prominent in particular muscles including biceps femoris muscle.
Conclusions: This trial is the first-in-man clinical trial to demonstrate that BCAA supplementation might be safe and, at least in part, improve skeletal muscle mass, strength, and function in patients with rheumatic disorders treated with GC.
Keywords: Branched-chain amino acids; Glucocorticoids; Rheumatic disorders; Skeletal muscle atrophy; mTOR.