[β-hydroxy-β-methylbutyrate as a dietary supplement (II): cell and molecular mechanism of action]

In recent years, several investigations have related -hydroxy--methylbutyrate (HMB) to a reduced muscle proteolysis and to an increase in muscle mass. Therefore, a number of studies focused on the cellular and molecular mechanisms regulating these effects have been carried out.

The objectives of this review are: to know both HMB metabolism and toxicity, and to identify HMB cellular and molecular mechanisms of action when used as a dietary supplement.

A search was performed in the Web of Science, Pubmed and SportDiscus data bases. RESULTS were divided into two parts; this article presents aspects referring to HMB mechanisms of action.

There is insufficient evidence that HMB intake increases muscle cholesterol synthesis. It probably has positive effects on muscle metabolism through both the mTOR and ubiquitin-proteasome pathways, although the mechanism of action is unknown. HMB may increase blood levels of -hydroxybutyrate and this could explain the main effects of HMB on muscle proteolysis.

According to these results, the possibility of justifying the action of HMB through the beta-hydroxybutyrate pathway opens an interesting line of research for future studies.