Dietary Supplement HMB

HMB is a dietary supplement designed and patented by Steve L. Nissen of Iowa State University. The supplement was originally marketed and distributed by the sport supplement company EAS based in Colorado with the claims that it prevents muscle breakdown after intense resistance exercise and that it increases lean muscles gains. Many other supplement manufacturers have HMB in their supplement lines today and still profess the same claims that EAS made when HMB hit the market. The recommended dosage for HMB is 3 grams daily which equates to 12 capsules of the product per day. The price of HMB varies, but is approximately $39.95 for a bottle of 200 capsules (1). This bottle will yield approximately 17 servings at a cost of approximately $2.50 per serving. With lofty claims and a high price it is important to determine if this supplement actually works.

HMB stands for beta-hydroxy-beta-methylbutyrate and is a metabolite of the branched-chain amino acid leucine. HMB is naturally occurring in the body in small quantities and is also found in foods such as grapefruit, alfalfa, and plant products such as corn silage (1). Because HMB is a naturally occurring substance in the body and in food that we eat it is claimed to be a completely safe supplement to take by those engaging in regular exercise. Recent studies have shown that HMB supplementation at 3 grams per day for 8 weeks showed no adverse health effects and actually improved mood, lowered total serum cholesterol, lowered LDL cholesterol, and lowered systolic blood pressure (3). These studies were conducted using both male and female subjects, young and old, exercising and non-exercising. Organ and tissue function was assessed using blood chemistry and hematology while tolerance to HMB was assessed using 32 health related questions (3). The data from this research suggests that in addition to providing exercise related benefits, HMB may help reduce cardiovascular risks such as heart attacks and stroke (3).

The safety of HMB has been established by research but what of the claims of increased lean muscle mass, increased strength and decreased muscle breakdown following exercise? There have been a multitude of studies trying to determine if this supplement actually does what its manufacturers claim. The initial study by Nissen in 1996 showed that supplementation with either 1.5g or 3g of HMB when combined with a resistance training program resulted in decrease muscle proteolysis, or muscle damage, and significantly increased muscle function, i.e. size and strength (4). Another recent study showed that although supplementation with HMB did not result in any change in body composition, it did result in significant increases in leg extension strength (9).

Additional studies of HMB supplementation have shown to reinforce previous findings that increased lean muscle mass and strength can result in conjunction with a resistance training program. A recent study by Panton et al. observed the effects of HMB supplementation on both male and female subjects over a 4-week period. The subjects were randomized into control (placebo) groups and HMB supplementation groups. Both groups followed the same resistance training program for the 4-week period while the experimental group supplemented with 3g of HMB daily. The results of the study showed the HMB group, regardless of gender or training status, increased lean muscle mass and increased strength (6).

In addition to studying the effects of HMB supplementation on resistance trained individuals, researchers have also studied the effects of HMB on endurance athletes. Vukovich and Dreifort examined the effects of HMB on VO2 peak and the onset of blood lactate accumulation in endurance trained cyclists. The cyclists were randomly assigned to one of three groups, a placebo group, a leucine group and an HMB group. They completed three 2-week supplementation periods followed by a 2-week wash out period (10). The authors concluded that the HMB group increased time to reach VO2 peak and also increased the onset of blood lactate accumulation suggesting possible positive effects on performance (10). Knitter et al. examined the effects of HMB on muscle damage of runners after a long distance run. The researchers measured the activities of enzymes creatine phosphokinase and lactate dehydrogenase to determine muscle damage. They found that those runners who supplemented with HMB had significantly less activity of creatine phosphokinase as well as significantly lower levels of lactate dehydrogenase. The authors concluded that supplementation with HMB helps reduce exercise-induced muscle damage (2).

While all this research in support of HMB supplementation looks promising, there are also several other studies that show HMB has little to no effect on muscle gains, strength gains, or changes in body composition. Researchers at Oklahoma State University studied the effects of HMB supplementation on 35 collegiate football players. The results of their study conclude there were no significant changes in muscular strength or body composition between the control group and the experimental group after 4 weeks of training (7).

Slater et al. investigated the effects of HMB supplementation in resistance trained men. The subjects were randomly assigned to either a placebo group, an HMB group given a standard capsule or an HMB group given a time-released capsule. Each group performed the same resistance training program for a period of 6 weeks. Various measures of body composition were taken at both 3 weeks and 6 weeks. The authors concluded that HMB supplementation did not have any influence on strength gains or changes in body composition (8). Finally, Paddon-Jones et al. studied the effects of HMB supplementation on eccentric muscle damage and found HMB had no beneficial effects on a variety of symptoms related to eccentric muscle damage. They symptoms included muscle soreness, swelling or muscle torque following eccentric exercises (5).

With all these contradictory studies being published, can we determine if HMB really works as claimed? The problem I found with most of the studies on HMB supplementation, producing results for or against, was that the studies were very short in duration and contained a very low number of subjects. Most of the studies resulting in positive outcomes on strength and muscle gain were between 3 and 8 weeks in duration and were comprised of previously untrained subjects. The positive effects of HMB could be masking the normal positive effects of regular resistance exercise and nutrition in previously untrained individuals. Conversely, the majority of studies with no positive effects of HMB were also very short in duration but contained highly trained subjects. Because these subjects were already highly trained, it may take longer to elicit the benefits of HMB supplementation on these individuals.

I have personally supplemented with HMB numerous times and found that I am less sore after an acute bout of resistance training and that my strength does appear to increase more significantly and sooner than without HMB supplementation. I have noticed that these results from HMB appear more pronounced when I am either starting back into my exercise program after a prolonged bout of not exercising or when I change from a hypertrophy-oriented program to a strength-oriented program. I think the research on HMB in regard to exercise enhancement needs to be expanded and done in larger and longer studies. I also think that more effort needs to be put toward determining the exact mechanism of HMB in the body and then researchers will be better able to conclude if HMB really works as claimed. The cost of HMB has come down significantly over the years and with the availability of online retailers, the price is very reasonable. From my experience and some of the research out there, I think HMB is a promising supplement and would recommend it to a client if that client were previously untrained or beginning a new phase of their resistance training program.

References 1. http://www.eas.com, Nov 29, 2004 2. Knitter AE, Panton L, Rathmacher JA, Petersen A, Sharp R. Effects of beta-hydroxy-beta-methylbutyrate on muscle damage after a prolonged run. J Appl Physiol.2000 Oct;89(4):1340-4. 3. Nissen S, Sharp RL, Panton L, Vukovich M, Trappe S, Fuller JC Jr. Beta-hydroxy-beta-methylbutyrate (HMB) supplementation in humans is safe and may decrease cardiovascular risk factors. J Nutr. 2000 Aug;130(8):1937-45. 4. Nissen S, Sharp R, Ray M, Rathmacher JA, Rice D, Fuller JC Jr, Connelly AS, Abumrad N. Effect of leucine metabolite beta-hydroxy-beta-methylbutyrate (HMB) on muscle metabolism during resistance-exercise training. J Appl Physiol. 1996 Nov;81(5):2095-104. 5. Paddon-Jones D, Keech A, Jenkinks D. Short term beta-hydroxy-beta-methylbutyrate supplementation does not reduce symptoms of eccentric muscle damage. Int J Sport Nutr Exerc Metab. 2001 Dec; 11(4):442-50. 6. Panton LB, Rathmacher JA, Baier S, Nissen S. Nutritional supplementation of the leucine metabolite beta-hydroxy-beta-methylbutyrate (HMB) during resistance training. Nutrition. 2000 Sep; 16(9):734-9. 7. Ransone J, Neighbors K, Lefavi R, Chomiak J. The effect of beta-hydroxy-beta-methylbutyrate on muscular strength and body composition in collegiate football players. J Strength Cond Res. 2003 Feb; 17(1):34-9. 8. Slater G, Jenkins D, Logan P, Lee H, Vukovich M, Rathmacher JA, Hahn AG. 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 Sep; 11(3):384-96. 9. Thomas JS. Beta-hydroxy-beta-methylbutyrate (HMB) supplementation of resistance trained men. Asia Pac J Clin Nutr. 2004; 13(Suppl):S59. 10. Vukovich MD, Dreifort GD. Effect o