Association between endogenous plasma beta-hydroxy-beta-methylbutyrate levels and frailty in community-dwelling older people

International society of sports nutrition position stand: β-hydroxy-β-methylbutyrate (HMB)

Position Statement: The International Society of Sports Nutrition (ISSN) bases the following position stand on an analysis of the literature regarding the effects of β-Hydroxy-β-Methylbutyrate (HMB). The following 12 points have been approved by the Research Committee of the Society: 1. HMB is a metabolite of the amino acid leucine that is naturally produced in both humans and other animals. 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. 2. 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. 3. There are no negative effects of HMB-Ca and HMB-FA on glucose tolerance and insulin sensitivity in humans. There may be improvements in glucose metabolism in younger adults. 4. The primary mode of action of HMB appears to be through its dual mechanism to enhance muscle protein synthesis and suppress muscle protein breakdown. HMB's activation of mTORC1 is independent of the leucine-sensing pathway (Sestrin2-GATOR2 complex). 5. HMB may help reduce muscle damage and promote muscle recovery, which can promote muscle growth/repair. HMB may also have anti-inflammatory effects, which could contribute to reducing muscle damage and soreness. 6. HMB consumption in close proximity to an exercise bout may be beneficial to increase muscle protein synthesis and attenuate the inflammatory response. HMB can provide a beneficial physiological effect when consumed both acutely and chronically in humans. 7. Daily HMB supplementation (38 mg/kg body weight) in combination with exercise training may improve body composition through increasing lean mass and/or decreasing fat mass with benefits in participants across age, sex, and training status. The most pronounced of these improvements in body composition with HMB have been observed in studies with robust resistance training programs and dietary control. 8. HMB may improve strength and power in untrained individuals, but its performance benefits in trained athletes are mixed and increase with an increase in study duration (>6 weeks). HMB's beneficial effects on athletic performance are thought to be driven by improved recovery. 9. HMB supplementation appears to potentially have a positive impact on aerobic performance, especially in trained athletes. The mechanisms of the effects are unknown. 10. HMB supplementation may be important in a non-exercising sedentary and aging population to improve muscle strength, functionality, and muscle quality. The effects of HMB supplementation with exercise are varied, but the combination may have a beneficial effect on the treatment of age-associated sarcopenia under select conditions. 11. HMB may be effective in countering muscle disuse atrophy during periods of inactivity due to illness or injury. The modulation of mitochondrial dynamics and lipid metabolism by HMB may be a potential mechanism for preventing disuse atrophy and aiding rehabilitation beyond HMB's effects on rates of muscle protein synthesis and degradation. 12. The efficacy of HMB in combination with certain nutrients may be enhanced under select conditions.

Ergogenic Benefits of β-Hydroxy-β-Methyl Butyrate (HMB) Supplementation on Body Composition and Muscle Strength: An Umbrella Review of Meta-Analyses

BACKGROUND

β-Hydroxy-β-methyl butyrate (HMB) is a metabolite of the amino acid leucine, known for its ergogenic effects on body composition and strength. Despite these benefits, the magnitude of these effects remains unclear due to variability among studies. This umbrella review aims to synthesize meta-analyses investigating the effects of HMB on body composition and muscle strength in adults.

METHODS

A comprehensive literature search was conducted in Scopus, PubMed and Web of Science without date or language restrictions until August 2024. The study protocol was registered at Prospero (No. CRD42023402740). Included studies evaluated the effects of HMB supplementation on body mass, fat mass (FM), fat-free mass (FFM), muscle mass and performance outcomes. Effect sizes (ESs) and 95% confidence intervals (CIs) were calculated, and a random-effects model was used for meta-analysis. Standard methods assessed heterogeneity, sensitivity and publication bias. The methodological quality of included studies was assessed using the AMSTAR2 tool.

RESULTS

Eleven studies comprising 41 data sets were included, with participants aged 23-79 years. HMB supplementation significantly increased muscle mass (ES: 0.21; 95% CI: 0.06-0.35; p = 0.004), muscle strength index (ES: 0.27; 95% CI: 0.19-0.35; p < 0.001) and FFM (ES: 0.22; 95% CI: 0.11-0.34; p < 0.001). No significant changes were observed in FM (ES: 0.03; 95% CI: -0.04 to 0.35; p = 0.09) or body mass (ES: 0.09; 95% CI: -0.06 to 0.24; p = 0.22). The quality assessment revealed that five studies were of high quality, three were of low quality and three were of critically low quality.

CONCLUSIONS

HMB supplementation may benefit individuals experiencing muscular atrophy due to physiological conditions, particularly enhancing muscle mass and strength without significant changes in fat mass or body weight.

Relationship of endogenous plasma concentrations of β-hydroxy β-methyl butyrate (HMB) with frailty in community dwelling older adults with type-2 diabetes mellitus

BACKGROUND

Supplementation with β-hydroxy β-methyl butyrate (HMB) appears to be effective in preserving muscle in older adults. However, the association between endogenously produced HMB with frailty has not been studied in people with chronic disease.

OBJECTIVES

The purpose of this study is to explore whether an association exists between endogenous HMB levels and frailty status in older adults with type-2 diabetes mellitus (T2DM).

METHODS

Data were taken from the Toledo Study of Healthy Ageing, a community-dwelling aged (65 years+) cohort. Frailty was assessed at baseline and at 2.99 median years according to the Frailty Phenotype (FP) standardized to our population and the Frailty Trait Scale 12 (FTS12). The associations between HMB levels and frailty were assessed using three nested multivariate logistic regressions and segmented by sex. Glucose, HMB and glucose interaction, age and body composition were used as covariables.

RESULTS

255 participants (mean age 75.3 years, 52.94% men) were included. HMB levels showed an inverse cross-sectional association with frailty, which was modified when the interaction term HMB*glucose was included, remaining significant only for FTS12 [OR (95% CI): 0.436 (0.253, 0.751), p-value 0.003]. The association between HMB endogenous levels and FTS12 appears to be independent of sex, in which the association was maintained after adjusting for the covariates. However, there appears to be threshold points for glucose levels, above which the protective effect of HMB is lost: 145.4 mg/dl adjusted by gender for the whole sample and 149.6 mg/dl and 138.9 mg/dl for men and women, respectively. Endogenous HMB levels were not found to be associated with incident frailty.

CONCLUSIONS

Cross-sectional analysis revealed that endogenous HMB levels were inversely associated with frailty as assessed by the FTS12 in older people with T2DM. This association was found to be dependent on circulating fasted glucose levels.