Saturday, January 22, 2011

Beta-Hydroxy-Beta Methylbutyrate Strikes Back: HMB Increases GH and IGF-1 at the Expense of Insulin Resistance

"HMB" - do you remember these three letters? If you have been around the supplement world in the early 2000s, you probably will. Beta-hydroxy-beta methylbutyrate (HMβ) is a metabolite of leucine which has been advertised to enhance exercise performance, reduce fatigue and promote muscle gains. Nothing of that has been substantiated within larger human studies, though; and thus HMB a former star among the amino acid supplements has almost been forgotten.

Now, a recent study from Brazil (Gerlinger-Romero. 2011) provides data suggesting that HMB may in effect raise the content of pituitary GH mRNA and growth hormone [GH], as well as hepatic IGF-I mRNA and serum IGF-I concentrations.
It was observed that the HMβ treatment induced an increase in GH mRNA by 65% (P < 0.001) and in GH content by 20% (P < 0.05) compared to control group. The IGF-I mRNA expression in liver, as well as the serum IGF-I concentration was also significantly increased in the HMβ-treated animals.
There are some downsides to these results, however. Firstly, this is another rodent study, so we do not know how the results of this 4 week intervention would translate to human beings. At least, other than in previous investigations, the amount of HMB, 320mg/kg body weight, which is equivalent to roughly 52mg/kg body weight in a human being, would be affordable, but ...
Figure 1: Effect of the HMβ-treatment on Insulin concentrations.
Data are expressed as mean ± SEM. *P < 0.05; n = 9–16 animals per group
(Gerlinger-Romero. 2011)
... and here comes secondly, the rats became hyperinsulinemic (cf. figure 1), or in other words HMB supplementation induced insulin resistance. With the latter being at the heart of the metabolic syndrome I would think twice before attempting to boost my growth hormone level with an amino acid metabolite that will compromise my body's insulin management.