Common Names

  • Beta-hydroxymethylbutyrate
  • beta-hydroxy-beta-methylbutyrate monohydrate

For Patients & Caregivers

How It Works

HMB has not been shown to treat or prevent cancer.

HMB is a breakdown product of the amino acid leucine. It and other amino acids (such as arginine and glutamine) are generally known to prevent or slow the damage to muscle cells that occurs with intense exercise or in advanced cancer and AIDS. HMB has been shown to increase muscle health, strength, and function in elderly female patients. It also helps to prevent muscle breakdown in elderly bedridden nursing home patients receiving tube feedings. In studies in both animals and healthy volunteers, HMB caused a decrease in total cholesterol and LDL (“bad”) cholesterol. Scientists are not exactly certain how HMB exerts these effects. HMB does not affect blood levels of testosterone or growth factors.

Purported Uses

  • To prevent or reverse weight loss (cachexia) and weakness associated with diseases such as cancer and AIDS
    Two small clinical trials support this use, but larger trials that follow patients for longer periods of time are needed.
  • To increase muscle mass
    Clinical trials show mixed results regarding this use. The results of one small study found that HMB may decrease muscle breakdown in bed-ridden elderly patients. Another small study found that a formula containing HMB, arginine, lysine, and ascorbic acid may improve muscle strength, health, and function in elderly women. However, further study is needed to confirm these effects.
  • To improve strength and endurance in athletes
    Clinical trials show mixed results regarding this use.

Side Effects

Chronic supplementation of HMB resulted in hyperinsulinemia (high insulin levels in the blood) in rats.

Back to top

For Healthcare Professionals

Scientific Name


Clinical Summary

Beta-hydroxy-beta-methylbutyrate (HMB) is a metabolite of the amino acid leucine. Patients use HMB for body strength, muscle gain, AIDS wasting, and cancer-related cachexia.

Clinical studies suggest that HMB increases lean weight gain and reduces adipose tissue (1) (2). It does not increase muscle strength (3) nor affect plasma levels of androgens, cortisol, or insulin (4), but improves some components of aerobic performance (5). HMB was shown to reduce muscle breakdown in bed-ridden elderly patients fed by nasogastric tube (9) . A formulation containing HMB, arginine, and lysine significantly improved muscle strength, health and function in elderly women (10) .
Conclusions of a systematic review indicate that HMB is effective in preventing exercise-related muscle damage in healthy trained and untrained individuals, as well as muscle loss during chronic disease (17). Data also indicate that HMB supplementation may improve pulmonary function in patients with chronic obstructive pulmonary disease (COPD), (11) and nitrogen balance in critically injured patients (12)

HMB may be of benefit in AIDS wasting (6), but additional research is necessary concerning use for cancer-related cachexia (7). A large randomized clinical study of HMB in patients with cancer cachexia failed to demonstrate a significant effect (8). However, supplementation with a combination of beta-hydroxy-beta-methylbutyrate, arginine and glutamine was effective in preventing radiation dermatitis in a study of head and neck cancer patients (18).

Purported Uses

  • Cancer-related cachexia
  • HIV- and AIDS-associated wasting
  • Strength and stamina
  • Weight gain

Mechanism of Action

In muscle cells, HMB is thought to restore the balance between intracellular protein synthesis and proteolysis, likely by activating the PI3K/Akt-dependent mammalian target of rapamycin (mTOR) and FoxO1/FoxO3a signaling pathway and the reduction of tumor necrosis factor alpha-interferon gamma-induced MuRF-1 expression, improving atrophy due to aging (19).

In animal models, HMB caused reductions in the total subcutaneous fat content and LDL cholesterol (15). But it did not affect circulating plasma levels of testosterone (4), cortisol, insulin-like growth factor-1 (IGF-1), or insulin (14). Supplemental HMB has been shown to enhance protein synthesis in skeletal muscle of neonatal pigs by stimulating translation initiation (20).

In a study of mice, HMB blocked sepsis-induced caspase 3, 20S proteasomal and PKR activation, and significantly attenuated diaphragm weakness, preserving the generation of muscle force. This may potentially be of use in infected patients by reducing the duration of mechanical ventilation and decreasing mortality (21). HMB was also shown to improve the proliferation of muscle stem cells in fast twitch plantaris muscles in aged rats. This is thought to be due to reduced apoptotic index in HMB treated muscles associated with enhanced satellite cell proliferation leading to increased differentiated myonuclei (22).

Adverse Reactions

Chronic supplementation of HMB resulted in hyperinsulinemia in rats (16).

Herb Lab Interactions

May reduce Low-density lipoprotein.

Dosage (OneMSK Only)


  1. Gallagher PM, et al. Beta-hydroxy-beta-methylbutyrate ingestion, part I: effects on strength and fat free mass. Med Sci Sports Exerc. 2000;32:2109-15.

  2. Lamboley CR, Royer D, Dionne IJ. Effects of beta-hydroxy-beta-methylbutyrate on aerobic-performance components and body composition in college students. Int J Sport Nutr Exerc Metab. 2007 Feb;17(1):56-69.

  3. Hsieh LC, Chow CJ, Chang WC, et al. Effect of beta-hydroxy-beta-methylbutyrate on protein metabolism in bed-ridden elderly receiving tube feeding. Asia Pac J Clin Nutr. 2010;19(2):200-8.

  4. Kuhls DA, Rathmacher JA, Musngi MD, et al. Beta-hydroxy-beta-methylbutyrate supplementation in critically ill trauma patients. J Trauma. 2007;62(1):125-31.

  5. Gerlinger-Romero F, Guimarães-Ferreira L, Giannocco G, Nunes MT. Chronic supplementation of beta-hydroxy-beta methylbutyrate (HMβ) increases the activity of the GH/IGF-I axis and induces hyperinsulinemia in rats. Growth Horm IGF Res. 2011 Apr;21(2):57-62.

  6. Molfino A, Gioia G, Rossi Fanelli F, Muscaritoli M. Beta-hydroxy-beta-methylbutyrate supplementation in health and disease: a systematic review of randomized trials. Amino Acids. 2013 Dec;45(6):1273-92.

  7. Wheatley SM, El-Kadi SW, Suryawan A, et al. Protein synthesis in skeletal muscle of neonatal pigs is enhanced by administration of β-hydroxy-β-methylbutyrate. Am J Physiol Endocrinol Metab. 2014 Jan 1;306(1):E91-9.

  8. Supinski GS, Callahan LA. β-hydroxy-β-methylbutyrate (HMB) prevents sepsis-induced diaphragm dysfunction in mice. Respir Physiol Neurobiol. 2014 Jun 1;196:63-8.

Back to top
Back to top
Email your questions and comments to

Last Updated