Hydroxymethylbutyrate (Hmb)

Other Name(s):

Beta-hydroxy-beta-methylbutyrate, B-Hydroxy B-Methylbutyrate Monohydreate, Beta-Hydroxy-Beta-Methylbutyric Acid, Calcium B-Hydroxy B-Methylbutyrate Monohydrate, Calcium HMB, Hidroximetilbutirato, HMB de Calcium, Hydroxyméthylbutyrate, Hydroxymethyl Butyrate, Hydroxyméthyl Butyrate.


Hydroxymethylbutyrate (HMB) is a chemical that is produced when the body breaks down leucine. Leucine is an amino acid, one of the building blocks of protein. People use HMB to make medicine.

HMB is used for increasing the benefits from weight training and exercise; and for treating diseases of the heart and blood vessels (cardiovascular disease), high cholesterol, and high blood pressure. In combination with the amino acids arginine and glutamine, HMB is also used for treating weight loss, weakness, and diarrhea in people with AIDS (AIDS-related wasting).

How does it work?

HMB might promote muscle growth. It seems to reduce the destructive breakdown of muscle in people with AIDS.


What is HIV? See Answer

Uses & Effectiveness

Possibly Effective for...

  • Increasing body weight and muscle in people with acquired immunodeficiency syndrome (AIDS). Taking HMB by mouth, along with the amino acids arginine and glutamine, seems to increase body weight and lean body mass in people with AIDS when used for 8 weeks. This combination may also improve the way the immune system works in these people.

Insufficient Evidence to Rate Effectiveness for...

  • Athletic performance. There is conflicting evidence about the usefulness of HMB for weight training. Some research suggests that taking HMB by mouth, alone or along with other supplements, might increase strength, improve body composition, and reduce muscle damage when used during resistance training or intense endurance exercises. However, other research suggests that HMB does not improve these outcomes. The reason for the conflicting results is not entirely clear. There is some evidence that HMB might be more effective in people who are just beginning to train than in well-trained athletes.
  • Disease-related weight loss (cachexia). Some research shows that taking HMB by mouth, along with the amino acids arginine and glutamine, seems to increase body weight and lean body mass in people with cancer-related cachexia when used for 24 weeks. However, taking this combination does not seem to improve body weight or lean body mass in people with rheumatoid arthritis related-cachexia when taken for 12 weeks.
  • High cholesterol. Early research suggests that HMB can lower cholesterol.
  • High blood pressure. Early research suggests that HMB can lower blood pressure.
  • Diseases of the heart and blood vessels (cardiovascular disease).
  • Other conditions.
More evidence is needed to rate the effectiveness of HMB for these uses.

Natural Medicines Comprehensive Database rates effectiveness based on scientific evidence according to the following scale: Effective, Likely Effective, Possibly Effective, Possibly Ineffective, Likely Ineffective, and Insufficient Evidence to Rate (detailed description of each of the ratings).

Side Effects

HMB is POSSIBLY SAFE for most people when taken by mouth, short-term. Doses of 3 grams per day or less for up to 8 weeks seem to be safe.


A Timeline of the HIV/AIDS Pandemic See Slideshow

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.


The following doses have been studied in scientific research:


  • For treatment of weight loss, weakness, and diarrhea related to AIDS (AIDS-related wasting): 3 grams HMB in combination with 14 grams each of arginine and glutamine in two divided doses daily.

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