If there was one bodybuilding supplement that threatened to take some of creatine’s spotlight in the 1990s, it was HMB, or β-hydroxy-β-methylbutyrate. Though it lost a little steam on its way to the nutritional Hall of Fame, HMB has been causing a stir again on the fitness scene in recent years, and much of the commotion centers on a specific form of the substance.
Like many other supplements, you can buy HMB as a liquid, in pill form, or as a powder, but a more fundamental difference is worth considering.
In particular, is the free acid form of HMB more potent for gaining mass than traditional HMB? And, so which is the best HMB supplement form?
HMB first grabbed headlines in the mid 1990s when a few supplement companies began promoting it as the next big muscle-builder among natural substances. Those claims were backed by anecdotal evidence and a solid theory.
The branched-chain amino acid leucine is known to both enhance the rate of protein synthesis and retard the rate of proteolysis, or protein breakdown, when taken in supplemental form. Early researchers found, though, that much more leucine was required for the latter effect, leading to speculation that it was a byproduct, or metabolite, of leucine that was responsible for suppressed proteolysis.
Subsequent studies found that one of those metabolites, HMB, did indeed slow down protein breakdown in many cases, especially when training was very intense or the subjects were new to weight training.
HMB has enjoyed moderate popularity over the last two decades, and during that time, virtually all of it was sold as a salt, calcium HMB. Pairing HMB with calcium allowed manufacturers to sell it in solid forms and increase its stability and shelf life.
Several reviews found that HMB helped many (but not all) lifters achieve better results in terms of muscle gains.
HMB Free Acid
In the early 2010s, scientists and supplement companies began examining what would happen if they DIDN’T bind HMB to calcium and instead gave it to subjects as a free acid. Early studies showed that HMB free acid, or HMB-FA appeared to be absorbed more quickly than the calcium form.
That makes sense from a chemical point of view because there is no ionic salt bond to break.
In 2014, researchers from the University of Tampa undertook a study to examine the more practical implications of using HMB-FA instead of calcium HMB.
For this experiment, 24 men with previous weight-training experience were administered three grams per day of either HMB-FA or a placebo and also performed identical training programs. In particular, they built up their intensities for eight weeks, overtrained for two weeks, and then “tapered” for two weeks of easier workouts.
At the end of the study, the HMB-FA subjects had gained, on average, more than three times the lean body mass that the placebo group achieved, with similar gains in strength.
So Which Is Best?
On the surface, it may appear that HMB-FA is a clear winner over the calcium form, but there are several unanswered questions.
While trained athletes have traditionally not responded well to HMB, and did so in the HMB-FA experiment, it would have been helpful if a third group were included to directly examine the results achieved with the two forms of HMB under identical conditions. Also, with just 24 overall subjects, this study suffers from the classic sample-size problem — it’s hard to extrapolate the results of a few to what you might expect to happen for most.
What is clear is that HMB — in either the free acid or calcium form — appears to help at least some lifters gain mass and strength better than if they did not use the supplement.
Assuming you get a clean bill of health from your doctor beforehand and you keep him informed of your supplement plans, HMB is probably worth a try. Give both forms a shot and see which one works better (or at all) for YOU.