HMB hydroxymethylbutyrate

β-Hydroxy-β-Methylbutyrate (HMB): A Comprehensive Reference

1. Identity

Chemical Names and Classification

Technically called beta-hydroxy-beta-methylbutyric acid, the chemical hydroxymethylbutyrate (HMB) is found naturally in the human body and is produced during the breakdown of the amino acid leucine. HMB (C₅H₁₀O₃) is a five-carbon branched-chain organic acid. It is also known by the synonym β-hydroxyisovalerate, and its CAS registry number is 625-08-1. In its free acid form, HMB can be represented as (CH₃)₂(OH)CCH₂COOH.

HMB is classified as a short-chain aliphatic carboxylic acid and is the active downstream metabolite of the essential branched-chain amino acid (BCAA) L-leucine. HMB (β-hydroxy-β-methylbutyrate) is the active metabolite of leucine, a branched-chain amino acid, and is naturally occurring in humans and animals.

Commercial Forms and Preparations

HMB is sold as an over-the-counter dietary supplement in the free acid form, β-hydroxy β-methylbutyric acid (HMB-FA), and as a monohydrated calcium salt of the conjugate base, calcium β-hydroxy β-methylbutyrate monohydrate (HMB-Ca, CaHMB).

CaHMB is a salt formed by the combination of HMB and calcium ions and is the most widely used form in industry. It exists as a white crystalline powder that is easily soluble in water and is often formulated into powders or capsules to facilitate storage and use. Studies have demonstrated that CaHMB is efficiently absorbed in the body, providing a steady supply of HMB. HMB-FA, the unbound form of HMB, can exist as either a liquid or a gel. Research indicates that this form may have a higher absorption rate than CaHMB.

Two forms of HMB have been studied: Calcium HMB (HMB-Ca) and a free acid form of HMB (HMB-FA). HMB-FA appears to lead to increased appearance of HMB in the bloodstream when compared to HMB-Ca, though recent results are mixed.

Natural Dietary Sources

While it can be found in small amounts in various foods like dairy products, citrus fruits, and fish, sufficient therapeutic levels are generally achieved through supplementation. Small amounts of HMB are present in many foods of animal and plant origin, especially alfalfa and catfish.

In humans, only approximately 5% of leucine is converted into HMB under physiological conditions, resulting in a modest endogenous production of about 0.2–0.4 g HMB per day. Given its limited synthesis and the low natural abundance of HMB in conventional food sources, achieving the most commonly studied dose of 3 g HMB/day requires targeted dietary supplementation. Since only a small fraction of HMB's metabolic precursor, L-leucine, is metabolized into HMB, pharmacologically active concentrations of the compound in blood plasma and muscle can only be achieved by supplementing HMB directly.

2. History and Discovery

Early Chemistry

While Russian chemists originally reported the chemical synthesis of HMB in 1877, the first documentation of HMB in humans was in 1968 from a patient with isovaleric acidemia, a condition that disrupts leucine metabolism.

Scientific Discovery and Early Research

The effects of HMB on human skeletal muscle were first discovered by Steven L. Nissen at Iowa State University in the mid-1990s. The story of HMB begins with initial work done by Steve Nissen's group at the University of Iowa aimed at improving the quality and quantity of meat produced from domestic animals. Their early manuscripts revealed that seven weeks of HMB feeding in broiler chickens resulted in a faster growth rate, reduction in mortality, and increased muscle yield.

Subsequent findings showed positive results as HMB decreased morbidity by 40% and mortality by 50% in young calves undergoing physiological stress from being transported cross-country, as well as increased milk fat percentage and weanling pig weight. From this initial animal work, it appeared that HMB possessed unique effects on promoting the retention and growth of lean mass while providing support to the immune system.

The first human study by Nissen et al. suggested that HMB exerts both anabolic and anti-catabolic effects, which drew attention from athletes and clinicians as a means to augment and/or preserve muscle mass alone or in conjunction with training. Commercially, HMB became available in the late 1990s and was primarily marketed to athletes and exercising individuals. Over the past 20 years, our understanding of this nutrient has increased immensely as hundreds of articles have been published investigating the mechanistic and applied effects of HMB across a variety of populations.

Nissen founded a company called Metabolic Technologies, Inc. (MTI) around the time of his discovery, which later acquired six HMB-related patents that the company has used to license the right to manufacture and incorporate HMB into dietary supplements.

Traditional Use Context

HMB has no documented history of use in traditional herbal medicine, folk remedies, or ethnopharmacological traditions. It is an endogenous metabolite identified and characterized through modern biochemistry and nutritional science. Its supplemental use is entirely a product of late-twentieth-century sports and clinical nutrition research, making it categorically distinct from botanicals and herbal preparations that carry centuries of documented traditional use.

3. Biochemistry: Active Compound and Metabolic Pathway

Biosynthetic Pathway from Leucine

Beta-hydroxy-beta-methylbutyrate (HMB) is a natural metabolite of leucine, one of the essential amino acids. First, during reversible transamination, leucine is converted to alpha-ketoisocaproic acid (alpha-KIC), which appears to be able to inhibit the breakdown of muscle proteins. Depending on whether alpha-KIC is in the mitochondria or cytoplasm, it is converted to isovaleryl-coenzyme A (isovaleryl-CoA) by KIC dehydrogenase, or to HMB by KIC dioxygenase, respectively.

Conversion to isovaleryl-CoA inside liver mitochondria occurs with 95% probability, while only 5% of leucine is converted to HMB in the cytosol. A fraction of KIC is decarboxylated and reduced in the liver to yield β-hydroxy-β-methylbutyrate (HMB), also known as β-hydroxyisovalerate (CAS 625-08-1). This reaction is catalyzed by ketoisocaproate dioxygenase (4-hydroxyphenylpyruvate dioxygenase; 4-HPPD; EC 1.13.11.27), which has been detected in the livers of rats and humans.

Downstream Metabolism of HMB

Metabolism of HMB in the cytosol involves joining a coenzyme A molecule (HMB-CoA), followed by the conversion of the resulting compound into beta-hydroxy-beta-methylglutaryl coenzyme A (HMG-CoA), which is the primary metabolite downstream of HMB. Another fate relates to the activation of HMB to HMB-CoA. Once converted to HMB-CoA, further metabolism may occur, either dehydration of HMB-CoA to MC-CoA, or a direct conversion of HMB-CoA to HMG-CoA, which provides substrates for intracellular cholesterol synthesis. Several studies have shown that HMB is incorporated into the cholesterol synthetic pathway and could be a source for new cell membranes that are used for the regeneration of damaged cell membranes.

HMB, a water-soluble metabolite of leucine, is excreted in the urine and is not reabsorbed by the kidneys back into the bloodstream. Studies have shown that approximately half of the supplemented HMB is lost through urine.

4. Mechanisms of Action

Anti-Catabolic Mechanisms

The ergogenic effects of HMB supplementation are related to the enhancement of sarcolemma integrity, inhibition of protein degradation (ubiquitin pathway), decreased cell apoptosis, increased protein synthesis (mTOR pathway), stimulation of the growth hormone/insulin-like growth factor-1 (GH/IGF-1) axis, and enhancement of muscle stem cells proliferation and differentiation.

Evidence from cachectic cancer studies suggests that HMB may inhibit the ubiquitin-proteasome proteolytic pathway responsible for the specific degradation of intracellular proteins. HMB inhibits the ubiquitin-proteasome proteolytic pathway which governs the degradation of intracellular proteins.

HMB can also increase protein synthesis by attenuating the common pathway that mediates the effects of catabolic factors such as lipopolysaccharide (LPS), tumor necrosis factor-α/interferon-γ (TNF-α/IFNγ), and angiotensin II. HMB acts by attenuating the activation of caspases-3 and -8, and the subsequent attenuation of the activation of PKR and reactive oxygen species (ROS) formation via down-regulation of p38 mitogen-activated protein kinase (p38MAPK). Increased ROS formation is known to induce protein degradation through the ubiquitin-proteasome pathway. HMB accomplishes this attenuation through the autophosphorylation of PKR and the subsequent phosphorylation of eIF2α, and in part, through the activation of the mTOR pathway.

Anabolic Mechanisms: mTOR and PI3K/Akt Signaling

HMB may also directly stimulate protein synthesis through an mTOR-dependent mechanism. In muscle cells, HMB stimulates cell growth and survival through MAPK/ERK pathways. HMB restored balance between intracellular protein synthesis and breakdown by activating PI3K/Akt-dependent mammalian target of rapamycin (mTOR). The stimulating effect of HMB on mTOR is eliminated with the introduction of rapamycin, an mTOR inhibitor.

Both leucine and its metabolites (α-ketoisocaproate [KIC] and HMB) are capable of ameliorating protein degradation in skeletal muscle. The inhibitory effects of HMB (at 50 μM) on protein degradation are more potent than leucine at physiologically relevant concentrations. The mechanism of HMB action is associated with the PI3K/Akt signaling pathway.

Cholesterol Synthesis and Membrane Integrity

In the process of cell growth and membrane repair, 3-hydroxy-3-methylglutaryl-CoA (HMG-CoA) is metabolized by HMB as the rate-limiting component of cholesterol synthesis. Consequently, HMB may contribute to cholesterol synthesis and lipid profiles. This mechanism also underlies HMB's proposed role in restoring the structural integrity of damaged sarcolemma (muscle cell membranes) following exercise-induced damage.

Hormonal Interactions

HMB is a leucine metabolite which is one of three branched-chain amino acids. HMB plays multiple roles in the human body, of which the most important ones include protein metabolism, insulin activity, and skeletal muscle hypertrophy.

5. Scientific Evidence by Area of Use

5a. Resistance Exercise Performance and Body Composition in Trained Individuals

HMB, a metabolite of the branched-chain amino acid leucine, is extensively used by athletes and bodybuilders to increase strength, muscle mass, and exercise performance. However, the evidence for benefits specifically in well-trained individuals is considerably weaker than for untrained or older populations.

A comprehensive systematic review and meta-analysis examined HMB with resistance exercise training (RET) in untrained and trained persons. Based on a lack of any discernible difference between the HMB-FA and HMB-Ca forms of the supplement in terms of anabolic properties, despite an ostensibly higher bioavailability of the FA-form versus the Ca-form of HMB, both forms were studied. A recent meta-analysis revealed a small significant effect for HMB supplementation on increasing muscle mass and function in a variety of clinical conditions characterized by loss of skeletal muscle mass and weakness.

The benefits of HMB are not well defined, and taking HMB is not expected to increase muscle strength by a meaningful amount in healthy people who exercise regularly. HMB is a metabolite of the essential amino acid leucine that plays an anticatabolic role in muscle tissue. In addition to preventing muscle protein breakdown, HMB may help improve strength and muscle mass in older adults, but evidence of a benefit for athletes is lacking.

In endurance and martial arts athletes, HMB supplementation revealed positive effects on specific aerobic capacity variables. Positive results were also disclosed in resistance-trained athletes, where changes in strength, body fat, muscle mass, anaerobic performance, and power output were observed; however, these findings come from a heterogeneous body of literature with mixed methodological quality.

5b. Muscle Mass, Strength, and Physical Function in Older Adults (≥50 years)

This is the clinical population for which HMB evidence is most extensive and most positive.

A meta-analysis including a total of 21 RCTs and 1,935 participants, all over the age of 50, showed a positive impact of HMB oral supplementation in improving muscle mass (appendicular skeletal muscle mass: WMD = 1.56 kg, 95% CI: 0.03–3.09 kg; lean mass: WMD = 0.28 kg, 95% CI: 0.16–0.41 kg), strength (handgrip strength: WMD = 0.54 kg, 95% CI: 0.04–1.04 kg; five-time chair stand test: WMD = −0.73 s, 95% CI: −1.35 to −0.11 s), and physical function (gait speed: WMD = 0.06 m/s, 95% CI: 0.01–0.10 m/s). Subgroup analysis revealed that a dosage of 3 g/day for more than 12 weeks had significant improvement and was recommended.

A separate systematic review and meta-analysis of ten trials (n = 596) combining resistance training with HMB found more modest results. Resistance training plus HMB produced modest and borderline significant improvements in handgrip strength (SMD 0.24; 95% CI 0.00–0.48; p = 0.05) and moderate benefits in Short Physical Performance Battery (SPPB) scores (SMD 0.54; 95% CI 0.12–0.95; p = 0.01). No significant effects were observed for gait speed, appendicular lean mass, muscle quality, fat mass, or body weight. Five trials (50%) were rated at high risk of bias, limiting confidence in pooled estimates. HMB supplementation combined with resistance training may yield modest improvements in functional performance, particularly handgrip strength and overall physical function, without statistically significant effects in body composition.

Importantly, not all analyses are positive. Data from 10 RCTs investigating HMB supplementation and physical function in adults aged 50 years or older, involving 384 participants, showed that HMB supplementation in addition to physical exercise has no or fairly low impact in improving body composition, muscle strength, or physical performance in adults aged 50 to 80 years, compared to exercise alone.

Studies performed with older people have demonstrated that HMB can attenuate the development of sarcopenia in elderly subjects and that the optimal effects of HMB on muscle growth and strength occur when it is combined with exercise. Several studies suggest that HMB supplementation is ineffective in healthy sedentary subjects.

5c. Sarcopenia

This body of research focuses on the role of HMB in the management of sarcopenia (age- or disease-related loss of muscle mass and function) in older persons. A small number of studies have shown increases in lean (muscle) mass and some muscle function and physical performance parameters in older people with or without resistance exercise, and preservation of muscle mass during bed rest. However, heterogeneous methodological approaches preclude solid conclusions, and more studies are needed to confirm the role of HMB as a promising agent to treat sarcopenia.

5d. Cancer and Disease-Related Cachexia

HMB, a metabolite of the essential amino acid leucine, is acknowledged for its powerful role in facilitating muscle protein synthesis, reducing muscle catabolism, and promoting fat-free mass accumulation. With well-documented anticatabolic, anabolic, and lipolytic effects, HMB has been extensively studied in clinical settings and has exhibited potential in mitigating muscle loss induced by aging, cancer cachexia, and sarcopenia.

A systematic review published in the Journal of Cachexia, Sarcopenia and Muscle specifically examined HMB in patients with active cancer. Considering higher-quality studies, evidence of a beneficial effect of HMB supplementation was found in four of four studies for muscle mass, two of two for muscle function, three of three for hospitalization outcomes, and five of seven for survival. In contrast, no beneficial effects of HMB on quality of life or body weight were found in two of four and three of five studies, respectively. A limited number of higher-quality studies evaluating the impact of HMB on cancer therapy-related toxicity, inflammation, and tumour response were observed. Although limited, current evidence suggests that HMB supplementation has a beneficial effect on muscle mass and function in patients with cancer. Well-designed trials are needed to further explore the clinical benefit of HMB supplementation in this patient population.

Studies performed under in vitro conditions and in various animal models suggest that HMB may be effective in treatment of muscle wasting in various forms of cachexia. However, there are few clinical reports of the effects of HMB on muscle wasting in cachexia; in addition, most of these studies evaluated the therapeutic potential of combinations of various agents.

It is unclear if HMB supplementation would also reduce the therapeutic effects of mTOR inhibitors used in cancer treatment. This is a clinically relevant consideration given HMB's stimulation of the mTOR pathway.

5e. AIDS-Related Wasting

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

5f. Immobilization and Bed Rest

Some studies have explored the role of HMB in chronic diseases associated with muscle wasting (cancer, acquired immunodeficiency syndrome, chronic obstructive pulmonary disease). Previous interventions in older adults who underwent orthopedic surgery found that HMB accelerated wound healing, reduced dependence on bed and immobilization period, and increased muscle strength.

5g. Cardiovascular Risk Factors and Lipid Profiles

The regulation of lipid metabolism is crucial for preventing cardiovascular diseases. HMB has garnered attention for its potential role in modulating lipid profiles. However, the magnitude of these effects is unclear due to the heterogeneity of the studies.

A review of nine clinical studies found a decrease in total cholesterol by 5.8%, LDL cholesterol by 7.3%, and an average decrease in systolic blood pressure by 3.3%. These results indicate that HMB-Ca is safe for use in the general population and provides some cardiovascular health benefits.

According to pooled results, supplementation with HMB decreased total cholesterol (TC) and LDL cholesterol levels. However, HMB has no significant effect on LDL levels in people with normal cholesterol levels. This may be interpreted as HMB lowering LDL levels in the presence of high cholesterol levels. Conversely, some studies have found that HMB supplementation does not significantly affect blood cholesterol levels.

One review concluded that chronic supplementation with HMB with resistance training does not reduce cardiovascular risk factors more than resistance training alone. In other words, the heart-protective effects of HMB may be due to an increase in exercise activity rather than the supplement itself. However, researchers also state that the amount of clinical research is limited.

5h. Hormonal Effects

A systematic review and meta-analysis (2024) examined HMB's effects on anabolic hormones. The studies evaluated the impact of HMB supplementation on hormonal outcomes, including testosterone, cortisol, insulin-like growth factor-1 (IGF-1), and growth hormone (GH). Utilizing a random-effects model with the GRADE framework, a total of 15 controlled trials comprising 712 participants were included. There are no negative effects of HMB-Ca and HMB-FA on glucose tolerance and insulin sensitivity in humans.

5i. Surgical Patients

Beta-hydroxy-beta-methylbutyrate (HMB) is a nutritional supplement that has demonstrated favorable effects on restoring muscle mass. However, evidence to support its use in patients undergoing surgery remains unclear. A 2025 systematic review and meta-analysis searched for RCTs focused on surgical patients receiving HMB, finding limited but emerging evidence in this population.

6. Body Systems and Health Areas

• Skeletal Muscle System: HMB is acknowledged for its powerful role in facilitating muscle protein synthesis, reducing muscle catabolism, and promoting fat-free mass accumulation.
• Musculoskeletal Function / Sarcopenia: With well-documented anticatabolic, anabolic, and lipolytic effects, HMB has been extensively studied in clinical settings and has exhibited potential in mitigating muscle loss induced by aging, cancer cachexia, and sarcopenia.
• Cardiovascular System: HMB's conversion to HMG-CoA links it mechanistically to cholesterol regulation. There are no negative effects of HMB-Ca and HMB-FA on glucose tolerance and insulin sensitivity in humans.
• Immune System: Initial animal work suggested that HMB possessed unique effects on promoting the retention and growth of lean mass while also providing support to the immune system.
• Oncology / Wasting Conditions: HMB finds applications in specialized medical nutrition, sports nutrition, and animal husbandry, with recent research illustrating its benefits in enhancing animal growth and immunity.
• Cellular Membrane Integrity: Several studies have shown that HMB is incorporated into the cholesterol synthetic pathway and could be a source for new cell membranes used for the regeneration of damaged cell membranes.

7. Dosage Forms and Reported Dosages

The optimal effects of HMB can be achieved at 3.0 grams per day when given as the calcium salt of HMB, or 0.038 g/kg of body weight per day, while those of leucine require over 30.0 grams per day.

Numerous studies have shown an effective dose of HMB to be 3.0 grams per day as CaHMB (~38 mg/kg body weight/day). This dosage increases muscle mass and strength gains associated with resistance training, while minimizing muscle damage associated with strenuous exercise.

Subgroup analysis in the meta-analysis of adults over 50 years old revealed that a dosage of 3 g/day for more than 12 weeks had significant improvement, and a dosage of 3 g/day for more than 12 weeks was recommended.

In previous human studies, CaHMB was given at up to 6 g per day for 8 weeks with no effect on renal or hepatic function nor on hematology. Currently, there have been two year-long human studies supplementing CaHMB, one at 2 g/day and the other at 3 g/day, and in each no adverse effects of supplementation have been reported.

For those involved in regular exercise who do choose to take this supplement, the research generally uses 3 grams of HMB per day in combination with resistive exercise, such as weight lifting.

Supplementing the diet with 3.0 g/day of Ca-HMB was safe and well tolerated for over 24 weeks in a cancer patient population.

8. Safety Considerations

General Safety Profile

The available safety/toxicity data suggest that chronic HMB-Ca and HMB-FA consumption are safe for oral HMB supplementation in humans up to at least one year.

In terms of toxicity, HMB-Ca and HMB-FA have a strong safety profile in humans. Consuming up to 6 g of HMB-Ca per day for up to 8 weeks did not lead to any changes in blood chemistries or the biochemical parameters of renal function, hepatic function, or hematology.

Clinical trials have not found any significant adverse effects with short-term HMB use. Short- and long-term toxicological studies in animals have also found no evidence of harm.

Preclinical Toxicology

Additional longer studies were carried out in rats fed diets containing 1%, 2%, or 5% food-grade HMB-Ca for 91 days, in compliance with FDA and GLP regulations. These showed no HMB-Ca-related adverse effects on clinical signs, body weight, feed consumption, clinical chemistry, hematology, organ weights, or tissue observations. The study established no-observed-adverse-effect levels (NOAEL) of 3.49 and 4.16 g/kg BW/day in male and female rats, respectively. Based on the FDA-recommended body surface area correction factors, these levels translate to approximately 0.5 g/kg BW/day in humans, corresponding to more than 30 g/day for a 60-kg person, which is more than 10 times the recommended dose.

Adverse Effects Reported in Clinical Populations

Side effects with HMB are generally mild and limited to gastrointestinal discomfort (e.g., heartburn, upset stomach, nausea, and flatulence).

Incidence of gastrointestinal adverse events was 15% in one cancer patient cohort, with two studies reporting a probable relationship between these events and HMB/Arg/Gln supplementation. No serious adverse events related to the nutrition intervention were recorded in three studies.

A study in college-aged men reported no changes in liver enzymes, lipids, renal function, or immune system markers after 8 weeks of HMB supplementation.

Drug Interactions

Minimal drug interactions have been reported between HMB and other medications, but research is limited. Although most studies report mild side effects (e.g., gastrointestinal discomfort) with HMB, other studies have reported no adverse effects.

A notable pharmacological concern involves the mTOR signaling pathway. The stimulating effect of HMB on mTOR is eliminated with the introduction of rapamycin, an mTOR inhibitor. It is unclear if HMB supplementation would also reduce the therapeutic effects of other mTOR inhibitors used in cancer treatment. This interaction remains theoretical but warrants clinical attention in oncology settings.

Pregnancy, Lactation, and Special Populations

Data assessing the safety and efficacy of hydroxymethylbutyrate (HMB) during pregnancy and lactation are limited, and some negative effects have been reported in animal studies. Avoidance is warranted.

Regulatory and Anti-Doping Status

As of 2018, HMB has not been banned by the National Collegiate Athletic Association, World Anti-Doping Agency, or any other prominent national or international athletic organization.

9. Overall Evidence Assessment

The body of research on HMB is large in number but frequently heterogeneous in quality. The clearest and most consistently supported application is in older adults (≥50 years) with or at risk for sarcopenia, particularly when supplementation at 3 g/day is combined with resistance exercise for durations exceeding 12 weeks. Evidence in well-trained younger athletes is weak and inconsistent, with most high-quality meta-analyses finding no meaningful benefit over placebo. While numerous studies have supported the efficacy of HMB in exercise and clinical conditions, there have been a number of conflicting results. Evidence in disease-related wasting (cancer cachexia, AIDS) is promising but remains limited by small sample sizes, use of multi-ingredient formulas, and heterogeneous methodologies. Some studies suggest that HMB supplementation may help reduce muscle tissue breakdown, enhance recovery after intense exercise, and improve muscle function in older adults, although research findings have been mixed and often lack large-scale studies.

References

• International Society of Sports Nutrition Position Stand: β-hydroxy-β-methylbutyrate (HMB) — PMC (2024)
• International Society of Sports Nutrition Position Stand: β-Hydroxy-β-Methylbutyrate (HMB) — Journal of the ISSN (Taylor & Francis, 2024)
• Mechanism of Action and the Effect of Beta-Hydroxy-Beta-Methylbutyrate (HMB) Supplementation on Different Types of Physical Performance — A Systematic Review (PMC, 2019)
• Physiological Benefits, Applications, and Future Directions of β-Hydroxy-β-Methylbutyrate (HMB) in Food and Health Industries — Foods, MDPI (2025)
• Physiological Benefits, Applications, and Future Directions of β-Hydroxy-β-Methylbutyrate (HMB) in Food and Health Industries — PMC (2025)
• Supplementation with the Leucine Metabolite β-hydroxy-β-methylbutyrate (HMB) does not Improve Resistance Exercise-Induced Changes in Body Composition or Strength in Young Subjects: A Systematic Review and Meta-Analysis — PMC (2020)
• Effects of Oral Supplementation of β-hydroxy-β-methylbutyrate on Muscle Mass and Strength in Individuals Over the Age of 50: A Meta-Analysis — PMC / Frontiers in Nutrition (2025)
• The Role of HMB Supplementation in Enhancing the Effects of Resistance Training in Older Adults: A Systematic Review and Meta-Analysis on Muscle Quality, Body Composition, and Physical Function — PMC (2025)
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• A 14C-Leucine Absorption, Distribution, Metabolism and Excretion (ADME) Study in Adult Sprague-Dawley Rat Reveals β-Hydroxy-β-Methylbutyrate as a Metabolite — PMC (2015)
• β-Hydroxy-β-methyl Butyrate (HMB) Supplementation Elevates Testosterone Levels Without Significant Changes to Cortisol, IGF-1, or Growth Hormone in Adults: A GRADE-Assessed Systematic Review and Meta-Analysis — PMC (2025)
• Effects of β-hydroxy-β-methylbutyrate (HMB) Supplementation on Lipid Profile in Adults: A GRADE-Assessed Systematic Review and Meta-Analysis of Randomized Controlled Trials — PMC (2024)
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• The Effects of Beta-Hydroxy-Beta-Methyl Butyrate Supplementation in Surgical Patients: A Systematic Review and Meta-Analysis — Frontiers in Nutrition (2025)
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• High-Dose Medium-Term HMB Supplementation Did Not Trigger Body Composition Changes in Trained and Untrained Males — Frontiers in Nutrition (2025)