HMB might promote muscle growth. It seems to reduce the destructive breakdown of muscle
HMB (short for β-Hydroxy β-Methylbutyrate) is a metabolite of the amino acid leucine that, along with KIC (α keto-isocaproate) and isovaleryl-CoA, mediate the effects of leucine. Approximately 5% of dietary leucine is oxidized into HMB, and HMB appears to be the main metabolite of leucine that more effectively prevents the breakdown of muscle protein.
HMB, currently, appears to be a pretty interesting supplement for the purpose of reducing muscle wasting during periods where muscle atrophy is accelerated and should theoretically work in athletes on a calorie restricted diet but is not fully established for this role yet (which is a notable issue, since glutamine has a large dichotomy between clinical and healthy populations).
How to Take HMB
Recommended dosage, active amounts, other details
Supplementation of HMB tends to be in the dosage range of 1-3g daily for the purpose of reducing muscle mass losses over time (anti-catabolic). As HMB is said to be 20-fold more potent than leucine for this purpose, it is seen as equivalent to 20-60g of leucine supplementation.
For the purpose of muscle protein synthesis, HMB and leucine are fairly equivalent if not the latter (leucine) being more potent on a gram basis. HMB is not advised for inducing muscle protein synthesis since leucine is likely more effective as well as cheaper.
Supplementation of HMB prior to an exercise session would require the usage of an HMB free acid rather than a calcium salt, and the above dosage range still holds. For this specific purpose, HMB is to be taken 30-45 minutes before a workout.
(Effective= 10/10) (Can be Effective 9/10) (Insufficient Evidence 8/10)
Age related muscle loss. Most research shows that taking HMB can slightly decrease the loss of muscle associated with aging (9/10)
High cholesterol. Early research suggests that HMB can lower cholesterol (8/10)
High blood pressure. Early research suggests that HMB can lower blood pressure (8/10)
Muscle strength. Most research shows that HMB helps increase muscle a little in people who are just beginning to train but not in well-trained athletes (8/10)
Disease-related weight loss (cachexia) (8/10)
Foot ulcers from diabetes (8/10)
Skin rash from radiation therapy for cancer (8/10)
Diseases of the heart and blood vessels (cardiovascular disease) (8/10)
HMB is POSSIBLY SAFE for most people when taken by mouth, short-term. Doses of 3 grams per day or less for up to one year seem to be safe.
Special Precautions & Warnings:
Pregnancy and breast-feeding: There is not enough reliable information about the safety of taking HMB if you are pregnant or breast-feeding. Stay on the safe side and avoid use.
Beta-hydroxy-beta-methylbutyrate, B-Hydroxy B-Methylbutyrate Monohydreate, Beta-Hydroxy-Beta-Methylbutyric Acid, Calcium B-Hydroxy B-Methylbutyrate Monohydrate, Calcium HMB, Hidroximetilbutirato, HMB, HMB de Calcium, Hydroxyméthylbutyrate, Hydroxymethyl Butyrate, Hydroxyméthyl Butyrate.<br/><br/> source: webmd & examine.com