# HMB (beta-hydroxy-beta-methylbutyrate)

Source: https://onco.cc/technologies/hmb-supplements/  
OnCo record `hmb-supplements` (Technology). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

HMB, a breakdown product of the amino acid leucine, is sold to preserve muscle and is added to some medical drinks for cancer weight loss, often with arginine and glutamine. A larger randomised trial of that combination in cancer wasting found no significant effect, and analyses show at most small gains in muscle across other illnesses.

## Summary

Memorial Sloan Kettering's About Herbs entry describes HMB as a leucine metabolite used to reduce muscle protein breakdown, with mixed results in young active men and some positive small studies in older people. Very few studies are in cancer: HMB is often combined with glutamine and arginine for muscle wasting and cachexia, but a larger randomised trial failed to show a significant effect; one small study suggests an HMB-containing supplement may help prevent radiation dermatitis in head and neck cancer. Meta-analyses across clinical conditions suggest small increases in muscle and strength, with little to no effect when added to exercise in older adults. Laboratory studies show HMB stimulates mTOR signalling, an effect reduced by the mTOR inhibitor rapamycin; whether HMB reduces the effectiveness of mTOR inhibitor drugs such as everolimus is not known. Nutritional assessment, adequate energy and protein, exercise and, where appropriate, licensed drugs for cachexia are the evidence-based approach.

## Fields

- Kind: Technology
- Status: negative
- Last checked: 2026-11-04
- Also known as: HMB; Beta-hydroxy-beta-methylbutyrate; HMB, arginine and glutamine
- Tags: complementary; supportive-care; evidence:no-benefit
- Principle: Reduces muscle protein breakdown and stimulates protein synthesis through mTOR in laboratory models.
- Strengths: Well tolerated; Small muscle gains in some clinical populations
- Limitations: Larger randomised trial in cancer wasting negative; Little added effect with exercise; Unknown interaction with mTOR inhibitors

## Sources

- MSK About Herbs: HMB (page last updated 13 January 2021): https://www.mskcc.org/cancer-care/integrative-medicine/herbs/hmb

## Connected records

- technologies: [Cachexia pharmacotherapy: GDF-15 blockade, anamorelin, olanzapine](https://onco.cc/technologies/cachexia-appetite-pharmacotherapy/), [Carnitine and acetyl-L-carnitine](https://onco.cc/technologies/carnitine-acetyl-l-carnitine/), [Creatine supplements](https://onco.cc/technologies/creatine-supplements/), [Dietary supplements during cancer treatment: interactions and harms](https://onco.cc/technologies/dietary-supplements-treatment-interactions/), [Evidence-based integrative oncology](https://onco.cc/technologies/integrative-oncology/), [Glutamine for mucositis and neuropathy](https://onco.cc/technologies/glutamine-mucositis-neuropathy/), [Resistance training and protein for cachexia and sarcopenia](https://onco.cc/technologies/resistance-training-cachexia/)
- fronts: [Diet, Exercise & Lifestyle](https://onco.cc/fronts/nutrition-lifestyle/), [Supportive Care & Survivorship](https://onco.cc/fronts/supportive-care/)
- drugs: [Everolimus](https://onco.cc/drugs/everolimus/), [Sirolimus](https://onco.cc/drugs/sirolimus/)
- terms: [Cancer cachexia](https://onco.cc/terms/cachexia/), [Radiation dermatitis (skin reaction)](https://onco.cc/terms/radiation-dermatitis/), [Sarcopenia](https://onco.cc/terms/sarcopenia/)
- bottlenecks: [Toxicity and quality of life are undervalued](https://onco.cc/bottlenecks/b-toxicity-qol/)

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