Does HMB improve protein balance in muscles?

Introduction

The leucine metabolite β-hydroxy-β-methylbutyrate (HMB) has been extensively studied for its potential to improve muscle protein balance, particularly in conditions of muscle wasting, aging, and during resistance exercise. This synthesis aims to evaluate whether HMB supplementation improves protein balance in muscles based on findings from multiple research studies.

Key Insights

Improvement in Muscle Protein Synthesis and Reduction in Protein Breakdown:
- HMB supplementation has been shown to acutely stimulate muscle protein synthesis (MPS) and inhibit muscle protein breakdown, particularly in older adults undergoing resistance exercise training (RET) .
- HMB appears to reduce muscle proteolysis more effectively than leucine, particularly in white muscle fibers, suggesting its role in decreasing muscle protein degradation.
Enhanced Muscle Mass and Function:
- HMB supplementation, especially when combined with high-protein diets or resistance exercise, has been found to improve muscle mass, strength, and physical performance in older adults and pre-frail individuals .
- In experimental models of cancer cachexia, HMB administration attenuated muscle and body weight loss, indicating its potential to improve protein anabolism in muscle.
Activation of Anabolic Pathways:
- HMB has been shown to activate key anabolic signaling pathways, such as the mTOR pathway, which is crucial for muscle protein synthesis. This activation was observed in both fasting-induced catabolic conditions and in cancer cachexia models .
Mixed Results in Different Populations:
- While HMB supplementation has shown promising results in older adults and individuals with muscle wasting conditions, its effects on muscle function and mass in sedentary aged rats were minimal, suggesting that the benefits of HMB may vary depending on the population and conditions studied.

Conclusion

HMB supplementation appears to improve muscle protein balance by stimulating muscle protein synthesis and reducing protein breakdown. These effects are particularly evident in older adults, individuals undergoing resistance exercise, and in conditions of muscle wasting such as cancer cachexia. The activation of anabolic pathways like mTOR further supports its role in enhancing muscle protein kinetics. However, the benefits of HMB may vary across different populations and conditions, indicating the need for further research to fully understand its potential.

Does HMB improve protein balance in muscles?

Summary

Consensus Meter

Introduction

Key Insights

Conclusion

Sources and full results

Anabolic effects of leucine-rich whey protein, carbohydrate, and soy protein with and without β-hydroxy-β-methylbutyrate (HMB) during fasting-induced catabolism: A human randomized crossover trial.

Leucine-rich whey protein and HMB beverages have superior anabolic effects on muscle protein kinetics during fasting-induced catabolic conditions, activating the mTOR pathway.

A double-blind placebo controlled trial into the impacts of HMB supplementation and exercise on free-living muscle protein synthesis, muscle mass and function, in older adults

HMB supplementation during resistance exercise in older adults enhances muscle protein synthesis and lean body mass, but not strength, in response to resistance exercise.

Oral Nutritional Supplement with β-hydroxy-β-methylbutyrate (HMB) Improves Nutrition, Physical Performance and Ameliorates Intramuscular Adiposity in Pre-Frail Older Adults: A Randomized Controlled Trial

Oral supplementation with HP-HMB improves muscle mass, strength, and physical performance in pre-frail older adults, while also reducing intramuscular adiposity.

Effects of beta-hydroxy-beta-methylbutyrate (HMB) on exercise performance and body composition across varying levels of age, sex, and training experience: A review

HMB may enhance exercise performance and muscle hypertrophy through various mechanisms, including inhibition of ubiquitin-proteasome protease and direct protein synthesis through an mTOR dependent mechanism.

β-hydroxy-β-methylbutyrate (HMB) attenuates muscle and body weight loss in experimental cancer cachexia.

HMB administration reduces body weight and muscle loss in experimental cancer cachexia, likely due to improved protein anabolism in muscle.

The leucine metabolite 3‐hydroxy‐3‐methylbutyrate (HMB) modifies protein turnover in muscles of laboratory rats and domestic chickens in vitro

HMB, a leucine metabolite, decreases muscle protein breakdown in vitro, supporting observations in humans.

Dietary HMB and β-alanine co-supplementation does not improve in situ muscle function in sedentary, aged male rats.

Dietary HMB and -alanine co-supplementation does not improve muscle function in sedentary, aged male rats, but may reduce muscle protein breakdown.

The Effect of β-Hydroxy-β-Methylbutyrate (HMB) on Sarcopenia and Functional Frailty in Older Persons: A Systematic Review

HMB supplementation improves lean muscle mass and preserves muscle strength and function in older people with sarcopenia or frailty.

Supplementing with beta-hydroxy-beta-methylbutyrate (HMB) to build and maintain muscle mass: a review.

HMB supplementation may help reduce protein degradation and increase muscle cell recovery, potentially improving strength and overcoming weakness.

β-Hydroxy-β-Methylbutyrate (HMB) Supplementation and the Promotion of Muscle Growth and Strength

HMB supplementation may promote muscle growth and strength in young, untrained individuals by acting as an anticatabolic agent, but more tightly controlled, longer duration studies are needed to confirm these claims across various groups.

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