Long-term Effects of Calcium β-Hydroxy-β-methylbutyrate (HMB) and Vitamin D3 Supplementation on Muscular Function in Older Adults with and without Resistance Training: A Randomized, Double-blind, Controlled Study.

The primary aim of this study was to determine whether supplementation with calcium beta-hydroxy-beta-methylbutyrate (HMB) and vitamin D-3 (D) would enhance muscle function and strength in older adults. Older adults over 60 years of age with insufficient circulating 25-hydroxy-vitamin D (25OH-D) levels were enrolled in a double-blinded controlled 12-month study. Study participants were randomly assigned to treatments consisting of: (a) Control + no exercise, (b) HMB+D + no exercise, (c) Control + exercise, and (d) HMB+D + exercise. The study evaluated 117 participants via multiple measurements over the 12 months that included body composition, strength, functionality, and questionnaires. HMB+D had a significant benefit on lean body mass within the nonexercise group at 6 months (0.44 +/- 0.27 kg, HMB+D vs -0.33 +/- 0.28 kg, control, p < .05). In nonexercisers, improvement in knee extension peak torque (60 degrees/s) was significantly greater in HMB+D-supplemented participants than in the nonsupplemented group (p = .04) at 3 months, 10.9 +/- 5.7 Nm and -5.2 +/- 5.9 Nm, respectively. A composite functional index, integrating changes in handgrip, Get Up, and Get Up and Go measurements, was developed. HMB+D + no exercise resulted in significant increases in the functional index compared with those observed in the control + no exercise group at 3 (p = .03), 6 (p = .04), and 12 months (p = .04). Supplementation with HMB+D did not further improve the functional index within the exercising group. This study demonstrated the potential of HMB and vitamin D-3 supplementation to enhance muscle strength and physical functionality in older adults, even in individuals not engaged in an exercise training program.