Hydroxymethylbutyrate (HMB) is a chemical that is made when the body breaks down leucine. Leucine is an amino acid, one of the building blocks of protein.

HMB might promote muscle growth. It can be found naturally in small amounts in grapefruit, alfalfa, and catfish. It's also naturally made in the body.

People use HMB for building muscle or preventing age-related muscle loss. It's also used for athletic performance, muscle loss due to HIV/AIDS, muscle strength, obesity, and many other purposes, but there is no good scientific evidence to support these uses.

Uses & Effectiveness ?

Possibly Effective for

  • Age-related muscle loss (sarcopenia). Taking HMB by mouth seems to increase muscle mass and might slow the loss of muscle in older adults. But it might not help any more than exercise.

Possibly Ineffective for

  • Physical performance in elderly adults. Taking HMB by mouth while participating in an exercise program doesn't improve physical performance any more than participating in the exercise program alone.
There is interest in using HMB for a number of other purposes, but there isn't enough reliable information to say whether it might be helpful.

Side Effects

When taken by mouth: HMB is possibly safe. Doses of up to 3 grams daily for up to one year have been used safely.

Special Precautions and Warnings

When taken by mouth: HMB is possibly safe. Doses of up to 3 grams daily for up to one year have been used safely.

Pregnancy and breast-feeding: There isn't enough reliable information to know if HMB is safe to use when pregnant or breast-feeding. Stay on the safe side and avoid use.

Interactions ?

We currently have no information for HYDROXYMETHYLBUTYRATE (HMB) overview.


HMB and a calcium salt of HMB (Ca-HMB) have most often been used by adults in doses of 2.4-3 grams by mouth daily. Speak with a healthcare provider to find out what type of product and dose might be best for a specific condition.
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CONDITIONS OF USE AND IMPORTANT INFORMATION: This information is meant to supplement, not replace advice from your doctor or healthcare provider and is not meant to cover all possible uses, precautions, interactions or adverse effects. This information may not fit your specific health circumstances. Never delay or disregard seeking professional medical advice from your doctor or other qualified health care provider because of something you have read on WebMD. You should always speak with your doctor or health care professional before you start, stop, or change any prescribed part of your health care plan or treatment and to determine what course of therapy is right for you.

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© Therapeutic Research Faculty 2020.