Old-fashioned calcium HMB works better than HMB Free Acid, says rival

HMB Free Acid, the miracle supplement that enables bodybuilders to gain 7 kg hard muscle in a couple of months, is now available in webstores. And just as we were about to dig into our pockets to try and reduce the difference between ourselves and Phil Heath, researchers at Abbott Nutrition Research and Development publish a study which suggests we’re better off spending our money on the old-fashioned type of HMB. We see quarrels ahead. Goodie goodie.


HMB Free Acid goes by the name of BetaTOR in supplement jargon. It was created by Metabolic Technologies, and is found in MuscleTech’s Clear Muscle. The difference between this and the old HMB is that HMB Free Acid is an acid [formula below], and the old HMB is a calcium salt [formula above]. Click here for more on HMB Free Acid.

If the – sponsored – studies are to be believed, HMB Free Acid is about to put all steroids dealers out of work. They put this down to the superior bioavailability of HMB Free Acid compared with HMB Old Shit.


Researchers at the rivals Abbott Nutrition recently published a study in the Journal of Nutrition in which they had given rats both versions of HMB. They took into account that HMB Old Shit contains calcium, so the rats got less (in grams) HMB Free Acid than calcium HMB per kg bodyweight.


And hey presto! In the rivals’ lab not a trace of superior bio-availability was to be seen in the HMB Free Acid.



“The stability of HMB in plasma was also tested, because unstable compounds tend to have a short half-life due to rapid clearance”, the researchers write. “However, both forms of HMB were found to be stable when incubated in plasma, demonstrating that the increased clearance of HMB Free Acid observed is not due to instability in plasma.”

“A structural analog of HMB, butyric acid, was demonstrated [Clin Chim Acta. 1989 May 31;181(3):255-63.] to undergo rapid oxidation after i.v. administration of 14C sodium salt, and liver was identified as the preferential site of uptake. Butyric acid demonstrated biphasic elimination pharmacokinetics in humans and rabbits, with a steep decline in concentration within the first 15 min, followed by a second phase of gradual elimination.”

“The elimination pharmacokinetics of HMB Free Acid mirrors that of butyric acid, with 50% of the administered dose being eliminated within the first 15 min. Given that the Vd of HMB Free Acid is higher than that of CaHMB, it is conceivable that HMB Free Acid partitions more rapidly into tissues. Whether the increased clearance of HMB Free Acid is due to increased tissue uptake and/or oxidation remains to be demonstrated.”


“A randomized crossover study (NCT01914952) is underway to understand the bioavailability of the 2 forms of HMB when both are given as a liquid supplement”, the researchers conclude. “The results of this study will provide further insights on the bioavailability of the 2 forms of HMB.”

Read more about the trial – financed by Metabolic Technologies – on clinicaltrials.gov. [NCT01914952] It was completed just a few weeks ago. No doubt we’ll be hearing more about it soon.

The Relative Bio-availability of the Calcium Salt of ?-Hydroxy-?-Methylbutyrate Is Greater Than That of the Free Fatty Acid Form in Rats.



?-Hydroxy-?-methylbutyrate (HMB) supplementation has been demonstrated to enhance muscle protein synthesis and attenuate loss of muscle mass by multiple pathways. The beneficial effects of HMB have been studied by using either the calcium salt, monohydrate, of HMB (CaHMB) or the free acid form (FAHMB).

The present study was designed to compare the pharmacokinetics and relative bioavailability of the 2 forms of HMB administered as a liquid suspension in male Sprague-Dawley rats.

CaHMB at 30, 100, and 300 mg/kg and equivalent doses of FAHMB at 24.2, 80.8, and 242 mg/kg were administered orally as a liquid suspension to male Sprague-Dawley rats. A single i.v. dose of 5 mg/kg CaHMB, corresponding to an equivalent dose of 4.04 mg/kg FAHMB, was also administered. Plasma concentrations of HMB were analyzed by liquid chromatography tandem mass spectrometry, and pharmacokinetic variables and relative bioavailability of the 2 forms of HMB were determined.


After oral administration, the area under the plasma concentration time curve (AUC) from time 0 to time t (0-t) and from time 0 to infinity (0-?) and the maximum (peak) plasma concentration (Cmax) for CaHMB were significantly greater than for FAHMB, whereas the time to reach Cmax did not differ from that of FAHMB. The relative bioavailability of CaHMB was 49%, 54%, and 27% greater than that of FAHMB for the 3 respective oral doses tested. After i.v. administration, the AUCs 0-t and 0-? of the calcium salt were significantly greater than those of FAHMB. The relative bioavailability of CaHMB was 80% greater than that of FAHMB. The higher relative bioavailability of CaHMB may be attributable to its low systemic clearance compared with FAHMB.


This study demonstrates the enhanced relative bioavailability of CaHMB compared with FAHMB. Further studies are warranted to understand the physiologic mechanisms contributing to the differences in systemic clearance.

PMID: 25143371 [PubMed – in process]

Source: http://www.ncbi.nlm.nih.gov/pubmed/25143371

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