Beta-Hydroxy beta-methylbutyric acid
- 3-methyl- 3- hydroxybutanoic acid
- 3- hydroxy isovaleric acid
- β - hydroxy isovaleric acid
- β -hydroxy- β -methyl butanoic acid
- β -hydroxy- β -methyl butyric acid
- HMB
Clear, colorless to slightly yellowish, viscous liquid with an unpleasant odor
Liquid
0.938 g · cm -3
-80 ° C
88 ° C ( 133 hPa)
Completely miscible with water
1.4415
Attention
Template: Infobox chemical / molecular formula search available
3-hydroxy- 3-methylbutyric acid, often abbreviated as HMB and generally referred to as β -hydroxy- β - methylbutyric acid, or β -hydroxy- β - methylbutyrate, is a metabolite of the essential amino acid L- leucine. The connection is since the beginning of the 21st century found in some dietary supplements and to have an anabolic effect.
Effect
About 5 percent of the recorded via the food leucine is metabolized into HMB. In the first step of leucine α - ketoisocaproate ( ketoleucine, KIC ) is formed. A part of the KIC is metabolized in the mitochondria by the enzyme α -keto acid dehydrogenase in isovaleryl -coenzyme A on. In the cytosol, however, is from KIC by the enzyme α - ketoisocaproate dioxygenase 3-hydroxy -3-methyl butyric acid ( HMB ) is formed. HMB is therefore a substance that is formed in any healthy body during metabolism.
The muscle proteins are made up about one-third of the branched chain amino acids leucine, L- isoleucine and L- valine. L- Leucine is important for maintaining and building muscle tissue. It inhibits the breakdown of muscle proteins and support protein synthesis in the liver and muscles. The administration of leucine has an anabolic effect.
HMB, the metabolic product of L- leucine is offered as a dietary supplement and is in the human body, among other anabolic, anti -catabolic, and lipolytic effects. HMB is therefore taken by many bodybuilders and strength or endurance athletes in the form of calcium -3- hydroxy-3- methylbutyrate ( " Ca - Hmb " ) in food supplements to increase muscle mass or performance legally. However, the results of scientific studies on the effects of HMB relative to the increase in muscle mass are very contradictory. A number of studies showing positive effects lasting other studies come to the conclusion that HMB has no effect. Largely undisputed is now the state of knowledge that HMB - compared to placebo - with well-toned athlete has no effect. Neither aerobic nor in anaerobic power an increase in performance by taking HMB was measured. In contrast, the administration of HMB appears to have positive effects in the affected patients in patients with muscular dystrophy, for example, as a result of AIDS or cancer disease ( cachexia ), with high probability.
HMB is well tolerated even at high doses. In animal studies, no adverse effects were observed.
Mechanism of action
In model organisms with cancer cachexia was reduced with HMB both the degradation of proteins, and the construction of muscle mass can be stimulated. HMB may regulate the expression of NF-KB, which is thus produced by the cells to a lesser extent. The mechanism for the synthesis of protein mass via the mTOR receptor whose phosphorylation is apparently stimulated by HMB.