Year-long Changes in Protein Metabolism in Elderly Men and Women Supplemented With a Nutrition Cocktail of β-Hydroxy-β-methylbutyrate (HMB), L-Arginine, and L-Lysine

Background: A major contributing factor to the loss of mobility in elderly people is the gradual and continuous loss of lean body mass. Objectives: To determine whether supplementation of an amino acid cocktail daily for 1 year could improve the age-associated changes in protein turnover and lean body mass in elderly people. Design: Elderly (76 +/- 1.6 years) women (n = 39) and men (n = 38) were recruited for a double-blinded controlled study. Study participants were randomly assigned to either an isonitrogenous control-supplement (n = 37) or a treatment-supplement (HMB/Arg/Lys) consisting of beta-hydroxy-beta-methylbutyrate, L-arginine, and L-lysine (n = 40) for the 1-year study. Lean tissue mass was measured using both bioelectrical-impedance analysis (BIA) and dual energy x-ray absorptiometry (DXA). Rates of whole-body protein turnover were estimated using primed/intermittent oral doses of N-15-glycine. Results: In subjects taking the HMB/Arg/Lys supplement, lean tissue increased over the year of study while in the control group, lean tissue did not change. Compared with control, HMB/Arg/Lys increased body cell mass (BIA) by 1.6% (P = .002) and lean mass (DXA) by 1.2% (P = .05). The rates of protein turnover were significantly increased 8% and 12% in the HMB/Arg/Lys-supplemented group while rates of protein turnover decreased 11% and 9% in the control-supplemented subjects (P < .01), at 3 and 12 months, respectively. Conclusions: Consumption of a simple amino acid-related cocktail increased protein turnover and lean tissue in elderly individuals in a year-long study. (JPEN J Parenter Enteral Nutr. 2009;33:71-82)