Hydroxymethyl butyrate


Beta-hydroxy beta-methylbutyrate (hydroxymethylbutyrate, or HMB) a breakdown product of the amino acid leucine. It can be found naturally in small quantities in grapefruit, alfalfa, and catfish.
HMB is also naturally synthesized in the human body. Production of HMB occurs in the muscle and liver, and it is believed to be involved in muscle protein synthesis. Currently, HMB is widely available and a popular supplement among athletes, especially bodybuilders.
Clinical trials have also reported HMB to be effective when used orally, in combination with amino acids, to prevent cachexia (loss of muscle) in patients with AIDS, cancer, and rheumatoid arthritis. Preliminary clinical evidence has indicated that HMB may lower blood pressure and cholesterol.

Related Terms

3-Hydroxy-3-methyl-butanoic acid, 3-hydroxyisobutyric acid, {beta}-hydroxy-{beta}-methylbutyrate, beta-hydroxy-beta-methylbutyric acid, beta-hydroxy-beta-methylglutarate-CoA, b-hydroxy-b-methylbutyrate monohydrate, branched-chain amino acids (BCAA), calcium beta-hydroxy-beta-methylbutyrate, creatinine, glutamine, HMB, HMG-CoA, HMG-CoA reductase, hydroxymethyl butyrate, hydroxymethylglutarate, ketoisocaproate, KIC, leucine.

evidence table

These uses have been tested in humans or animals. Safety and effectiveness have not always been proven. Some of these conditions are potentially serious, and should be evaluated by a qualified healthcare provider.
Exercise recovery (Grade: B)
HMB has been found to reduce muscle damage associated with exercise and to shorten recovery time. Supplementation has been found to inhibit muscle breakdown and enhance protein synthesis.
Cachexia (Grade: C)
HMB in combination with arginine and glutamine has been shown to decrease both cancer- and AIDS-related cachexia (weight loss/wasting). Evidence remains insufficient for use of HMB alone in the treatment of cachexia.
Cardiovascular disease risk (Grade: C)
In preliminary research, HMB supplementation was found to reduce cardiovascular disease risk factors. HMB lowered total and low-density lipoprotein (LDL) cholesterol and reduced systolic blood pressure. Well-designed clinical trials are needed to confirm these findings.
Exercise performance (Grade: C)
Reviews examining HMB's effects on exercise performance have noted increases in lean body mass and strength in response to supplementation. Other studies, however, did not support these findings. Additional research is required.
Wound healing (Grade: C)
HMB in combination with arginine and glutamine has been shown to enhance collagen synthesis. Additional research is required before any recommendation can be made.