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HMB (beta hydroxy-beta-methylbutyrate) is a metabolite of the essential amino acid leucine (one of the branched-chain amino acids).
Small amounts of HMB are present in many foods of animal and plant origin, especially alfalfa and catfish. The amino acid leucine is metabolized into a compound called alpha-ketoisocaproate (KIC), which is then turned into HMB by the body. Dietary supplements of HMB are also available.
Some athletes say that HMB
HMB may assist in accelerating the loss of body fat.
Exercise-induced muscle protein breakdown appears to decrease with HMB supplementation. This, in turn, should speed up recovery from exercise-induced muscle damage.
Enhanced strength and increased muscle mass have been documented in people supplementing with HMB. However, to date, a very limited number of studies have been done. Longitudinal studies to indicate possible long-term use effects of HMB have not been completed.
Biochemical and animal research shows HMB has a role in protein synthesis and might improve muscle growth and overall body composition as a supplement. However, double-blind human research suggests that HMB may only be effective when combined with an exercise program in people who are not already highly trained athletes. Double-blind trials found no effect of 3 to 6 grams per day HMB on body weight, body fat, or overall body composition in weight-training football players or other trained athletes.1 2 3 4 5 However, one double-blind study found that 3 grams per day HMB increased the amount of body fat lost by 70-year old adults who were participating in a strength-training program for the first time.6 A double-blind study of young men with no strength-training experience reported greater improvements in muscle mass (but not in percentage body fat) when HMB was used in the amount of 17 mg per pound of body weight.7 However, another group of men in the same study given twice as much HMB did not experience any changes in body composition.
No safety issues have been reported in the limited number of studies currently available.
At the time of writing, there were no well-known drug interactions with HMB.
*Athletes and fitness advocates may claim benefits for HMB based on their personal or professional experience. These are individual opinions and testimonials that may or may not be supported by controlled clinical studies or published scientific articles on HMB. For more complete and detailed information, including references and safety information, see HMB as a nutritional supplement.
1. Ransone J, Neighbors K, Lefavi R, Chromiak J. The Effect of beta-hydroxy beta-methylbutyrate on muscular strength and body composition in collegiate football players. J Strength Cond Res 2003;17:34–9.
2. Kreider R, Ferreira M, Wilson M, Almada AL. Effects of calcium beta-HMB supplementation with or without creatine during training on body composition alterations. FASEB J 1997;11:A374 [abstract].
3. Slater G, Jenkins D, Logan P, et al. Beta-hydroxy-beta-methylbutyrate (HMB) supplementation does not affect changes in strength or body composition during resistance training in trained men. Int J Sport Nutr Exerc Metab 2001;11:384–96 [review].
4. Kreider RB, Ferreira M, Wilson M, et al. Effects of calcium beta-hydroxy-beta-methylbutyrate (HMB) supplementation during resistance-training on markers of catabolism, body composition and strength. Int J Sports Med 1999;20:503–9.
5. Slater GJ, Jenkins D. Beta-hydroxy-beta-methylbutyrate (HMB) supplementation and the promotion of muscle growth and strength. Sports Med 2000;30:105–16.
6. Vukovich MD, Stubbs NB, Bohlken RM. Body composition in 70-year-old adults responds to dietary beta-hydroxy-beta-methylbutyrate similarly to that of young adults. J Nutr 2001;131:2049–52.
7. Gallagher PM, Carrithers JA, Godard MP, et al. Beta-hydroxy-beta-methylbutyrate ingestion, Part I: effects on strength and fat free mass. Med Sci Sports Exerc 2000;32:2109–15.
Copyright © 2007 Healthnotes, Inc. All rights reserved. www.healthnotes.com
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The information presented in Healthnotes is for informational purposes only. It is based on scientific studies (human, animal, or in vitro), clinical experience, or traditional usage as cited in each article. The results reported may not necessarily occur in all individuals. For many of the conditions discussed, treatment with prescription or over the counter medication is also available. Consult your doctor, practitioner, and/or pharmacist for any health problem and before using any supplements or before making any changes in prescribed medications. Information expires September 2008.
