To the Editor:
Nunan et al. (4) recently published a study entitled: “Exercise-induced muscle damage is not attenuated by β-hydroxy-β-methylbutyrate (HMB) and alpha-ketoisocaproic acid supplementation,” where they examined the effects of combined oral HMB and α-ketoisocaproic acid (KIC) supplementation on indices of exercise-induced muscle damage (EIMD) after an acute bout of eccentric-biased exercise. The authors hypothesized that 14 days of HMB (HMB-1000™) and KIC supplementation would reduce indices of muscle damage after an acute bout of downhill running. The researchers took measurements of isometric and concentric muscle strength, serum creatine kinase activity, delayed-onset muscle soreness, range of motion, and limb girth at pre-exercise and at 24, 48, and 72 hours postexercise. The authors concluded that HMB and KIC did not reduce signs and symptoms associated with EIMD after a 30-minute bout of downhill running. Before accepting this conclusion and dismissing the study hypothesis, several factors need to be considered.
First, it should be noted that the authors used a trademarked product by Maximuscle Ltd. of Watford, United Kingdom, called HMB-1000. The trademark “HMB” was filed in the United Kingdom in November of 1995 shortly after Nissen et al. first reported the effects of HMB in human subjects on muscle protein metabolism. The trademark case details (2045876) state that HMB™ is a class of dietetic preparations and substances, all providing human nutrition for athletes to increase lean body mass, reduce body fat, and increase lean tissue. The product label for HMB™ describes it as an “enzymatic metabolite of the amino acid leucine.” Neither case describes HMB™ as the amino acid leucine metabolite, HMB. However, the authors make the assumption that HMB-1000™ is 98% pure HMB. Instead, it was pure “enzymatic metabolites of leucine,” one of the ingredients listed in Maximuscle's HMB-1000™ label. β-Hydroxy-β-methylbutyrate is patented in the United States (US Patent 5,348,979 “Method of Promoting Nitrogen Retention in Humans”) and the United Kingdom (EP0637239). “β-Hydroxy-β-methylbutyrate” has been used in the scientific literature to describe HMB (5,6).
Secondly, we have obtained a bottle of HMB-1000™ (lot 632400) from Maximuscle Ltd.. We performed analysis on the capsule contents using high performance liquid chromatography and integrated using the 32 Karat™ software. (Beckman Counter System Gold™, Brea, CA, USA). Figure 1 compares a pure HMB standard (>99% purity, Lonza Group Ltd, Basel, Switzerland) to the HMB-1000™. The chromatograph of the standard in Figure 1A has 1 peak for HMB at 4.3 minutes. The chromotograph in Figure 1B has a major split peak at 2.9 minutes and smaller peak at 7.3 minutes, demonstrating the absence of HMB in HMB-1000™.
Based on the above, we believe that Nunan et al. (4) supplemented subjects with HMB-1000™ that contains no HMB. The authors can only conclude that Maximuscle HMB-1000™ did not reduce signs and symptoms associated with EIMD after a 30-minute bout of downhill running. β-Hydroxy-β-methylbutyrate has previously been shown to reduce EIMD in various situations (1-3) and the absence of HMB in HMB-1000™ may explain the lack of effect of EIMD.
Naji N. Abumrad, MD, FACS
Professor and Chairman, Department of Surgery, Vanderbilt University School of Medicine, Nashville, Tennesse. e-mail: naji. email@example.com.
John A. Rathmacher, PhD
Assistant Collaborating Professor, Department of Animal Science, Iowa State University, Ames, Iowa. e-mail: firstname.lastname@example.org.
1. Gallagher, PM, Carrithers, JA, Godard, MP, Schulze, KE, and Trappe, SW. β-hydroxy-β-methylbutyrate ingestion, Part I: Effects on strength and fat free mass. Med Sci Sports Exerc
32: 2109-2115, 2000.
2. Knitter, AE, Panton, L, Rathmacher, JA, Petersen, A, and Sharp, R. Effects of β-hydroxy-β-methylbutyrate on muscle damage following a prolonged run. J Appl Physiol
89: 1340-1344, 2000.
3. Nissen, S, Sharp, R, Ray, M, Rathmacher, JA, Rice, J, Fuller, JC Jr, Connelly, AS, and Abumrad, NN. The effect of the leucine metabolite β-hydroxy-β-methylbutyrate on muscle metabolism during resistance-exercise training. J Appl Physiol
81: 2095-2104, 1996.
4. Nunan, D, Howatson, G, and van Someren, KA. Exercise-induced muscle damage is not attenuated by beta-hydroxy-beta-methylbutyrate and alpha-ketoisocaproic acid supplementation. J Strength cond Res
24: 531-537, 2010.
5. Talleyrand, VZ, Zhang, Z, Rathmacher, J, and Nissen, S. Uptake and output of the leucine metabolite beta-hydroxy-beta-methylbutyrate (HMB) across the leg of pigs [Abstract]. FASEB J
7: A71, 1993.
6. Zhang, Z, Talleyrand, V, Rathmacher, J, and Nissen, S. Change in plasma Beta-hydroxy-Beta-methylbutyrate (HMB) by feeding leucine, alpha-ketoisocaporate (KIC) and isovaleric acid (IVA) to pigs [Abstract]. FASEB J
7: A392, 1993.