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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

From the ¹ Department of Food Science and Human Nutrition, Iowa State University, Ames; ² Department of Surgery, Vanderbilt University Medical Center, Nashville, Tennessee;³ Department of Animal Science, Iowa State University, Ames, IA; and ⁴ Metabolic Technologies, Iowa State University Research Park, Ames, IA.

Address correspondence to: Steven Nissen, DVM, PhD, Department of Animal Science, 313 Kildee Hall, Iowa State University, Ames, IA 50011; e-mail: nissen{at}iastate.edu.

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 β-hydroxy-β-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 ¹⁵N-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.

Key Words: L-arginine • L-lysine • β-hydroxy-β-methylbutyrate, aging • FFM • lean mass • protein turnover

Journal of Parenteral and Enteral Nutrition, Vol. 33, No. 1, 71-82 (2009)
DOI: 10.1177/0148607108322403


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