Thursday, July 31, 2008

Research Review--HMB, A New Review Published

Up now is a great review of the sports supplement HMB. I met Jacob briefly at ACSM and he hinted at some new data on HMB and it is released now.

You may remember HMB as being popular about 10 years ago (or maybe not). There were some great studies (not sure I agree with that) on it, but in reality it just never seemed to pan out. It did not help that the patent on it was held by Dr. Nissen--Hmmm. This is not inherently bad, but makes you want to dig a little deeper. See the patent HERE for yourself. Although HMB has sort of stood the test of time as it is still around and from a research stand point, we could learn some cool stuff.

HMB, or "beta-hydroxy beta-methylbutyrate", is a second downstream metabolite of the amino acid Leucine and is produced naturally by the human body. HMB is produced from a metabolite of leucine, called ketoisocaproate (KIC), by the enzyme KIC-dioxygenase. If you have been around for a bit like myself, you will remember KIC as a supplement too. Personally, it did not do squat for me and tasted absolutely horrible and was stupid expensive. I worked at a supplement store while I was going to college the first 8 years and got it for dirt cheap when it did not sell it. It was back when they sold things in actual glass containers! I am feeling old now.

I will hold any future thought for now since the review is very comprehensive and all the others did their homework on it. Writing a review is a MUCH bigger pain in the butt than most realized, so kudos to them for all the outstanding work on it. It allows people like myself (and you) to sit back with a good cup of dark coffee and read the most recent work without spending hours and hours combing through 100+ papers.

Here is a link to the FULL study

Effects of beta-hydroxy-beta-methylbutyrate (HMB) on exercise performance and body composition across varying levels of age, sex, and training experience: A review.

Wilson GJ
, Wilson JM, Manninen AH.

Division of Nutritional Sciences, University of Illinois, Urbana, Illinois, USA.

ABSTRACT: The leucine metabolite beta-hydroxy-beta-methylbutyrate (HMB) has been extensively used as an ergogenic aid; particularly among bodybuilders and strength/power athletes, who use it to promote exercise performance and skeletal muscle hypertrophy. While numerous studies have supported the efficacy of HMB in exercise and clinical conditions, there have been a number of conflicting results. Therefore, the first purpose of this paper will be to provide an in depth and objective analysis of HMB research. Special care is taken to present critical details of each study in an attempt to both examine the effectiveness of HMB as well as explain possible reasons for conflicting results seen in the literature. Within this analysis, moderator variables such as age, training experience, various states of muscle catabolism, and optimal dosages of HMB are discussed. The validity of dependent measurements, clustering of data, and a conflict of interest bias will also be analyzed. A second purpose of this paper is to provide a comprehensive discussion on possible mechanisms, which HMB may operate through. Currently, the most readily discussed mechanism has been attributed to HMB as a precursor to the rate limiting enzyme to cholesterol synthesis HMG-coenzyme A reductase.

However, an increase in research has been directed towards possible proteolytic pathways HMB may operate through. Evidence from cachectic cancer studies suggests that HMB may inhibit the ubiquitin-proteasome proteolytic pathway responsible for the specific degradation of intracellular proteins. HMB may also directly stimulate protein synthesis, through an mTOR dependent mechanism. Finally, special care has been taken to provide future research implications.

Any comments, let me know.
Rock on
Mike N