Molecular Formula:C5H10O3

Molecular Weight:118.1311

Alias:Hydroxyisovaleric acid; 3-hydroxy-3-methylbutanoic acid; β-Hydroxy-β-MethylButyric acid; HMB

Hydroxymethylbutyrate (HMB), otherwise known as its conjugate base, Hydroxymethylbutyrate (HMB), is a naturally produced substance in humans. HMB is an active metabolite of leucine. It 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.
Hydroxymethylbutyrate (HMB) has the following applications/functions:
1. Hydroxymethylbutyrate (HMB) is used as a dietary supplement and as an ingredient in certain medical foods that are intended to promote wound healing and provide nutritional support for people with muscle wasting due to cancer or HIV/AIDS.
2. In healthy adults, supplementation with HMB has been shown to increase exercise-induced gains in muscle size, muscle strength, and lean body mass, reduce skeletal muscle damage from exercise, improve aerobic exercise performance, and expedite recovery from exercise. Medical reviews and meta-analyses indicate that HMB supplementation also helps to preserve or increase lean body mass and muscle strength in individuals experiencing age-related muscle loss. HMB produces these effects in part by stimulating the production of proteins and inhibiting the breakdown of proteins in muscle tissue.  No adverse effects from long-term use as a dietary supplement in adults have been found.
3. Supplemental HMB has been used in clinical trials as a treatment for preserving lean body mass in muscle wasting conditions, particularly sarcopenia, and has been studied in clinical trials as an adjunct therapy in conjunction with resistance exercise. Based upon two medical reviews and a meta-analysis of seven randomized controlled trials, HMB supplementation can preserve or increase lean muscle mass and muscle strength in sarcopenic older adults. HMB does not appear to significantly affect fat mass in older adults.