November 4, 2004
1- Featured Article: HMB: Where’s the beef?
This Month’s Featured Article:
HMB: Where’s the beef?
by Alfredo Franco PhD
There are several interesting cases where the livestock industry has led to important developments in the human athletic arena. Such was the case for HMB (beta-Hydroxy-beta-MethylButyrate). In the search for the optimal amino acid balance to increase the muscle (meat) content of cattle only one branched-chain amino acid was found to possess particularly promising affects – leucine. However, the quantities of leucine that had to be administered to cows by way of their feed to observe an increase in meat (skeletal muscle) production made the feasibility of lysine supplementation impractical. Eager researchers then commenced to examine all the different metabolites of leucine in hopes of pinpointing the exact causative agent for the muscle growth promoting effects. With this information in hand, the industry could then effectively concentrate leucine’s anabolic punch and realistically maximize beef production. When the laboratory dust finally settled HMB stood alone, since showing to enhance bovine meat production effectively.
Does HMB improve human anabolics as well?
The next obvious question is: “Does HMB put forth an equally anabolic effect in human athletes as well?” It appears so, but in a more subtle way than other muscle promoting supplements. HMB does not directly stimulate muscle growth, instead protecting against excessive muscle loss that follows intense bouts of exercise; thus, in this manner accentuating muscle development. In the jargon of the field: HMB is anti-catabolic instead of pro-anabolic. Interestingly, the exact biochemical mechanism whereby HMB exerts its anti-catabolic influence remains largely obscure, even today. Conversely, one effect of HMB is well understood. HMB within the cell predominantly converts into HMG-CoA (beta-Hydroxy-beta-MethylGlutaryl CoA), which in turn, is the predecessor to cholesterol.
What’s so great about cholesterol?
Cholesterol is of the utmost importance in maintaining cellular membranes functions: properly keeping things inside the cell from getting out and keeping things (ions) outside the cell from getting in. Strenuous exercise, the most effective stimulus for new muscle growth, stresses our muscle membranes to the point of damage. This is not to say that SOME muscle damage is a terrible thing. In fact, SOME muscle damage is necessary to spur muscle growth. The operative word here is SOME. Excessive muscle damage pushes the scale in the opposite direction, counteracting muscle growth and causing overall muscle tissue loss. That is to overdo it in the gym, without providing muscles with the right nutritional support to overcome the damage, sets one into a catabolic (muscle-wasting) holding pattern; negating any benefits that training might have had to offer in the first place. Fascinatingly, research has revealed that interfering with the synthesis of cholesterol results in muscle damage. Presumably because muscle is unable to adequately overcome the mechanical stress of ordinary physical movement. While this is an extreme example, it does illustrate the importance to cholesterol for proper muscle functioning.
Does HMB raise serum cholesterol?
Ironically, despite its essential role in cholesterol synthesis, HMB supplementation has been shown to concurrently decrease total cholesterol, bad cholesterol (LDL), and systolic blood pressure. Therefore, in the long term HMB may provide a protective influence over the development of Coronary Heart Disease in later life. The possible benefit of HMB supplementation certainly merits further investigation in the medical arena. Nevertheless, these attributes of HMB should translate into greater gains in fat-free mass and strength during resistance training as well as improve overall health status.
What are natural sources of HMB?
Obviously, increasing your leucine intake will be reflected in increased levels of HMB within the cell. Approximately 5% of all dietary leucine is converted into HMB by the cells of the body. Natural sources also exist, by way of catfish, grapefruit, and alfalfa.
Is HMB safe?
HMB appears to be relatively side-effect free and, in fact possesses potentially beneficial properties for athletic performance and cardiovascular health. Most scientific studies have used HMB in the dose range of 1.5-3 grams per day, usually taken in one gram doses distributed throughout the day.
Ample studies have clearly shown that HMB protects our muscle from excessive damage following intense exercise. And, since intense exercise is the optimal stimulus for new muscle growth, HMB will play a crucial role in accentuating muscle development. New research has now shown that creatine monohydrate augments and extends the benefits of HMB. How to best combine these two important supplements for optimal anabolics is detailed in Creatine: A practical guide..
Nissen S., Sharp R.L., Panton L., Vukovich M., Trappe S., Fuller J.C. Jr. (2000) Beta-hydroxy-beta-methylbutyrate (HMB) supplementation in humans is safe and may decrease cardiovascular risk factors. Journal Nutrition Volume 130 (8), pages 1937-1945
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