Alcohol and Skeletal Muscle in Health and Disease

Association between caffeine intake and fat free mass index: a retrospective cohort study

BACKGROUND

Caffeine, identified as a central nervous system stimulant in foods, beverages (coffee, tea, chocolate), and medications, has been focused on its ergogenic properties, enhancing physical performance. The aim of this study was to investigate the association between the caffeine intake (from coffee) and fat-free mass index (FFMI).

MATERIALS AND METHODS

We carried out a cohort study that included 3,466 women and 3,145 men aged ≥20 years who were intaking caffeine. Caffeine intake from coffee were obtained from two 24-hour dietary recall interviews. The FFMI was calculated as FFM (kg) divided by height in m2. The caffeine intake was classified into quartiles and combined into 4 groups. Multiple linear regression model analysis and multiple logistic regression model analysis were used to assess associations between the caffeine and FFMI adjusted for potential confounders.

RESULTS

Among the 2,427 participants, males accounted for 52.4%, and females 47.6%. In multiple linear regression model, Model 1 (unadjusted Model (p = 0.041)) and Model 2 (adjusted for age, race, and BMI (p = 0.006)) in women showed a significant relationship between caffeine intake and FFMI. In multivariable models, caffeine intake and FFMI were significantly different (p < 0.05). In sex subgroups, among females, each quartile of caffeine intake was positively correlated with FFMI levels in the average FFMI group in Model 3 (p < 0.001). In age subgroups, each quartile of caffeine intake was positively correlated with FFMI levels in the average FFMI group in Model 3 for individuals aged 20-40 (p = 0.039) and those aged above 40 (p = 0.016). In drinking status subgroups, if they drunk alcohol, each quartile was positively correlated with FFMI levels in the average FFMI group in Model 3 (p < 0.001).

CONCLUSION

Caffeine intake was mainly positively associated with FFMI, especially in women with above levels of FFMI. Longitudinal studies and randomized controlled trials are needed to establish causality and provide evidence-based recommendations regarding caffeine intake to optimize muscle health.

Integrated Multiomics Analyses of the Molecular Landscape of Sarcopenia in Alcohol-Related Liver Disease

BACKGROUND

Skeletal muscle is a major target for ethanol-induced perturbations, leading to sarcopenia in alcohol-related liver disease (ALD). The complex interactions and pathways involved in adaptive and maladaptive responses to ethanol in skeletal muscle are not well understood. Unlike hypothesis-driven experiments, an integrated multiomics-experimental validation approach provides a comprehensive view of these interactions.

METHODS

We performed multiomics analyses with experimental validation to identify novel regulatory mechanisms of sarcopenia in ALD. Studies were done in a comprehensive array of models including ethanol-treated (ET) murine and human-induced pluripotent stem cell-derived myotubes (hiPSCm), skeletal muscle from a mouse model of ALD (mALD) and human patients with alcohol-related cirrhosis and controls. We generated 13 untargeted datasets, including chromatin accessibility (assay for transposase accessible chromatin), RNA sequencing, proteomics, phosphoproteomics, acetylomics and metabolomics, and conducted integrated multiomics analyses using UpSet plots and feature extraction. Key findings were validated using immunoblots, redox measurements (NAD+/NADH ratio), imaging and senescence-associated molecular phenotype (SAMP) assays. Mechanistic studies included mitochondrial-targeted Lactobacillus brevis NADH oxidase (MitoLbNOX) to increase redox ratio and MitoTempo as a mitochondrial free radical scavenger.

RESULTS

Multiomics analyses revealed enrichment in mitochondrial oxidative function, protein synthesis and senescence pathways consistent with the known effects of hypoxia-inducible factor 1α (HIF1α) during normoxia. Across preclinical and clinical models, HIF1α targets (n = 32 genes) and signalling genes (n > 100 genes) (n = 3 ATACseq, n = 65 phosphoproteomics, n = 10 acetylomics, n = 6 C2C12 proteomics, n = 106 C2C12 RNAseq, n = 64 hiPSC RNAseq, n = 30 hiPSC proteomics, n = 3 mouse proteomics, n = 25 mouse RNAseq, n = 8 human RNAseq, n = 3 human proteomics) were increased. Stabilization of HIF1α (C2C12, 6hEtOH 0.24 ± 0.09; p = 0.043; mALD 0.32 ± 0.074; p = 0.005; data shown as mean difference ± standard error mean) was accompanied by enrichment in the early transient and late change clusters, -log(p-value) = 1.5-3.8, of the HIF1α signalling pathway. Redox ratio was reduced in ET myotubes (C2C12: 15512 ± 872.1, p < 0.001) and mALD muscle, with decreased expression of electron transport chain components (CI-V, p < 0.05) and Sirt3 (C2C12: 0.067 ± 0.023, p = 0.025; mALD: 0.41 ± 0.12, p = 0.013). Acetylation of mitochondrial proteins was increased in both models (C2C12: 107364 ± 4558, p = 0.03; mALD: 40036 ± 18 987, p = 0.049). Ethanol-induced SAMP was observed across models (P16: C2C12: 0.2845 ± 0.1145, p < 0.05; hiPSCm: 0.2591, p = 0.041). MitoLbNOX treatment reversed redox imbalance, HIF1α stabilization, global acetylation and myostatin expression (p < 0.05).

CONCLUSIONS

An integrated multiomics approach, combined with experimental validation, identifies HIF1α stabilization and accelerated post-mitotic senescence as novel mechanisms of sarcopenia in ALD. These findings show the complex molecular interactions leading to mitochondrial dysfunction and progressive sarcopenia in ALD.

Prognostic significance of skeletal muscle mass in patients with alcohol-related cirrhosis

AIM

This study aimed to assess the prognostic significance of hand grip strength (HGS) and skeletal muscle mass index (SMI) in patients with alcohol-related cirrhosis.

METHODS

535 patients with liver cirrhosis (LC) were assessed for HGS and computed tomography (CT)-based SMI. They were categorized into alcohol-related liver disease (ARLD; n = 226), metabolic dysfunction-associated steatohepatitis (MASH; n = 119), and virus-related cirrhosis (VC, n = 190) groups.

RESULTS

Overall prevalence of sarcopenia was 16.4%, 11.8%, and 27.4% in the ARLD, MASH, and VC groups, respectively. Three factors including low SMI, low albumin (Alb) levels, low sodium (Na) levels, and two factors including low HGS and low Alb levels, and three factors including the presence of ascites, low cholinesterase (Ch-E) levels, and low HGS were identified as prognostic factors for mortality in the ARLD, MASH and VC groups, respectively. In the ARLD group, overall survival (OS) was significantly lower in low SMI + low HGS and normal HGS + low SMI (pre-sarcopenia) than in normal SMI and HGS. OS was significantly lower in sarcopenia than in normal SMI + low HGS (dynapenia). In the MASH group, OS was significantly lower in sarcopenia and dynapenia than in normal SMI and HGS. In the VC group, OS was significantly lower in sarcopenia and dynapenia than in normal SMI and HGS; OS was significantly lower in sarcopenia than in pre-sarcopenia.

CONCLUSIONS

In the ARLD group, SMI could serve as a more powerful predictor of survival than HGS.

Impact of Alcohol Intake on Body Composition in Patients with Steatotic Liver Disease

Objectives: To examine the effect of alcohol intake on body composition in patients with steatotic liver disease (SLD). Methods: In men, group A (n = 819) was defined as non-drinkers, group B (n = 1147) as <30 g of ethanol equivalent per day, group C (n = 125) as between 30 and 60 g/day, and group D (n = 344) as >60 g/day. In women, group A (n = 749) was defined as non-drinkers, group B (n = 354) as <20 g/day, group C (n = 36) as between 20 and 50 g/day, and group D (n = 68) as >50 g/day. The fat-free (FF) index and fat (F) index were defined as FF mass and F mass divided by height squared (kg/m2). Results: The average FF index and F index in groups A, B, C, and D in men were 19.01, 19.29, 18.50, and 18.55 kg/m2 (overall p < 0.0001), and 6.28, 6.71, 5.66, and 6.03 kg/m2 (overall p < 0.0001). The average FF index and F index in groups A, B, C, and D in women were 16.03, 15.96, 15.62, and 15.07 kg/m2 (overall p < 0.0001), and 9.89, 9.02, 9.32, and 7.53 kg/m2 (overall p < 0.0001). Conclusions: Heavy drinking has a negative effect on skeletal muscle and fat, but complete abstinence from alcohol may not be necessary in SLD patients.

Impact of Alcohol Intake on Skeletal Muscle: A Large Cross-Sectional Analysis in Japanese Adults

AIMS

To clarify the impact of alcohol intake on skeletal muscle mass (SMM) using data from Japanese health checkup recipients (8405 males and 11,509 females). The fat-free (FF) index was regarded as the FF mass divided by height squared (kg/m2).

METHODS

The subjects were classified into four groups (type A (never drinker), B (chance or mild drinker), C (moderate drinker), and D (severe drinker)) according to the amount of alcohol consumed.

RESULTS

The average age in males and females was 52.2 and 50.1 years, respectively (p < 0.0001). The average FF index in males and females was 18.5 and 15.1 kg/m2, respectively (p < 0.0001). The proportion of subjects of type A, B, C, and D was 36.5%, 44.2%, 5.9%, and 13.4%, respectively, in males, and 59.8%, 31.3%, 3.7%, and 5.1%, respectively, in females (p < 0.0001). The average FF index in type A, B, C, and D males was 18.43, 18.62, 18.12, and 18.16 kg/m2, respectively (overall p < 0.0001). The average FF index in type A, B, C, and D females was 15.17, 15.14, 15.15, and 14.78 kg/m2, respectively (overall p < 0.0001).

CONCLUSIONS

Habitual heavy drinking has a negative effect on SMM. However, from the standpoint of maintaining SMM, it is not necessary to completely abstain from alcohol.

Alcohol in Daily Products: Health Risks, Cultural Considerations, and Economic Impacts

Ethanol, a bioactive compound prevalent in both social and industrial applications, is present in alcoholic beverages as well as a range of everyday products. In food, ethanol functions primarily as an additive or a by-product of fermentation, while in pharmaceuticals and cosmetics, it serves as a solvent or preservative. Despite its widespread use, three critical research gaps exist in current literature. First, existing research focuses predominantly on single-sector analyses, overlooking the cumulative effects of cross-sectoral ethanol exposure. Second, despite growing global market integration, there is limited understanding of how cultural and religious requirements influence ethanol-related regulations and product formulations. Third, current economic models fail to integrate both health impact costs and cultural compliance expenses, hindering effective policy development. The World Health Organization has determined that no amount of alcohol consumption can be considered entirely safe, as ethanol's health impacts include contributions to chronic diseases, neurotoxicity, and potential carcinogenic effects. These risks are compounded by the pervasive and often unrecognized presence of ethanol in various products, particularly affecting vulnerable populations. The economic burden associated with alcohol-related issues, including lost productivity and healthcare costs, highlights the necessity for robust public health strategies and stringent regulatory guidelines. This review investigates ethanol's role across multiple domains, emphasizing its presence in food, medicine, cosmetics, and industrial products, and evaluates its broader implications for public health, cultural practices, and economic impact. This review recommend implementing standardized labeling systems, establishing cultural-sensitive alternatives in product formulations, and developing harmonized international guidelines for ethanol use across industries.

Cannabis (THC) Aggravates the Deleterious Effects of Alcohol (EtOH) on Skeletal Muscles' Mitochondrial Respiration: Modulation by Age and Metabolic Phenotypes

The anti-inflammatory and analgesic properties of cannabis might be useful to treat muscle diseases, including those linked or not to alcohol. Nevertheless, delta 9 tetrahydrocannabinol (THC) and ethanol (EtOH), often used concomitantly, can have deleterious effects on cardiac mitochondria. We therefore determined whether EtOH, alone and associated with THC, impairs skeletal muscle mitochondrial respiration. Further, we investigated potential modulation by metabolic phenotype and age by analyzing predominantly glycolytic gastrocnemius and oxidative soleus muscles in young and middle-aged rats (12 and 49 weeks). Considering the gastrocnemius, EtOH impaired mitochondrial respiration in a similar manner in young- and middle-aged muscles (-34.97 ± 2.97% vs. -37.50 ± 6.03% at 2.1 × 10-5 M; p < 0.05). Interestingly, concomitant THC aggravated EtOH-related mitochondrial impairment in young gastrocnemius (-49.92 ± 1.69%, vs. -34.97 ± 2.97 p < 0.05). Concerning the soleus, EtOH alone mainly decreased young muscle mitochondrial respiration (-42.39 ± 2.42% vs. -17.09 ± 7.61% at 2.1 × 10-5 M, p < 0.001, at 12 and 49 weeks). The soleus was less impaired at 12 weeks by THC and EtOH association than the gastrocnemius (-49.92 ±1.69 vs. -27.22 ± 8.96% in gastrocnemius and soleus, respectively, p < 0.05). In conclusion, EtOH, alone and associated with THC, significantly impairs skeletal muscle mitochondrial respiration and THC aggravates EtOH-induced effects on young glycolytic muscle. Age and metabolic phenotypes modulate these deleterious effects, with the glycolytic muscles of young rats being more prone to impairments than oxidative muscles.

Alcohol Alters Skeletal Muscle Bioenergetic Function: A Scoping Review

Bioenergetic pathways uniquely support sarcomere function which, in turn, helps to maintain functional skeletal muscle (SKM) mass. Emerging evidence supports alcohol (EtOH)-induced bioenergetic impairments in SKM and muscle precursor cells. We performed a scoping review to synthesize existing evidence regarding the effects of EtOH on SKM bioenergetics. Eligible articles from six databases were identified, and titles, abstracts, and full texts for potentially relevant articles were screened against inclusion criteria. Through the search, we identified 555 unique articles, and 21 met inclusion criteria. Three studies investigated EtOH effects on the adenosine triphosphate (ATP)-phosphocreatine (PCr) system, twelve investigated EtOH effects on glycolytic metabolism, and seventeen investigated EtOH effects on mitochondrial metabolism. Despite increased ATP-PCr system reliance, EtOH led to an overall decrease in bioenergetic function through decreased expression and activity of glycolytic and mitochondrial pathway components. However, effects varied depending on the EtOH dose and duration, model system, and sample type. The results detail the EtOH-induced shifts in energy metabolism, which may adversely affect sarcomere function and contribute to myopathy. These findings should be used to develop targeted interventions that improve SKM bioenergetic function, and thus sarcomere function, in people with Alcohol Use Disorder (AUD). Key areas in need of further investigation are also identified.

Effects of common lifestyle factors on obstructive sleep apnea: precautions in daily life based on causal inferences

Background

This study aimed to evaluate the causal impact of common modifiable lifestyles on obstructive sleep apnea (OSA), which is beneficial for recommendations to prevent and manage OSA.

Method

Published genome-wide association study (GWAS) summary statistics were used to perform two-sample Mendelian randomization (MR). Variants associated with each exposure of smoking, drinking, and leisure sedentary behaviors at the genetic level were used as instrumental variables (IVs). Then, inverse-variance weighting (IVW) was considered the primary result for causality. Moreover, several complimented approaches were also included to verify the observed associations. MR-PRESSO and MR-Egger intercept were applied to test the horizontal pleiotropy. To assess heterogeneity, Cochran's Q test by IVW and MR-Egger were applied.

Results

Regular smoking history increased OSA risk in all applied approaches [OR (95% CI)IVW = 1.28 (1.12, 1.45), p = 1.853 × 10-4], while the causality of lifetime smoking index [OR (95% CI)IVW = 1.39 (1.00, 1.91), p = 0.048], alcohol intake frequency [outliers removed OR (95% CI)IVW = 1.26 (1.08, 1.45), p = 0.002], and coffee intake behavior [OR (95% CI)IVW = 1.66 (1.03, 2.68), p = 0.039] on OSA risk were not always consistent in other approaches. In addition, no robust causal associations were observed for the effect of sedentary leisure behaviors on OSA risk. In sensitivity analysis, we observed no sign of horizontal pleiotropy or heterogeneity.

Conclusion

Ever regularly smoking has a robust causal role in increasing OSA risk, which should be discouraged as precautions from developing OSA.