Vitamin D status affects strength gains in older adults supplemented with a combination of β-hydroxy-β-methylbutyrate, arginine, and lysine: A cohort study

Abstract

Background: Older adults supplemented for 1 year with β-hydroxy- β-methylbutyrate, arginine, and lysine (HMB/ARG/LYS) were previously shown to have significant gains in fat-free mass (FFM) but not muscular strength. Objective: Recently, increasing levels of serum vitamin D have been associated with an increase in muscle function, particularly in the elderly. To determine if vitamin D status may have limited strength gain in participants supplemented with HMB/ARG/LYS, the authors performed post hoc analysis of strength based on the participants' vitamin D status. Methods: Elderly (age 76.0 ± 1.6 years) adults were recruited for a double-blinded, controlled study and were randomly assigned to either an isonitrogenous control (n = 37) or HMB/ARG/LYS (n = 40) for the yearlong study. Participants were further segregated based on their vitamin D status of either <30 or ≥30 ng 25OH-vitD3/mL serum, and an analysis was performed on the 4 cohorts. Results: Regardless of vitamin D status, HMB/ARG/LYS resulted in significantly increased FFM (P <30 ng 25OH-vitD3 failed to show improvements in strength. Conclusions: The nutrient cocktail of HMB/ARG/LYS alone was effective in increasing muscle mass regardless of vitamin D status, but accompanying strength increases were observed only when participants also had adequate vitamin D status indicating a synergistic effect between the HMB/ARG/LYS and vitamin D. © 2011 The American Society for Parenteral and Enteral Nutrition.