Rationale for antioxidant supplementation in sarcopenia

Meat consumption and the risk of hip fracture in women and men: two prospective Swedish cohort studies

PURPOSE

To study the association between meat intake (predominantly red and processed meats) and the risk of hip fracture, as well as the association between meat intake and biomarkers of inflammation, oxidative stress, bone turnover, body composition, and bone mineral density (BMD).

METHODS

Data from the Swedish Mammography Cohort and the Cohort of Swedish men (n = 83,603, 54% men) with repeated investigations and their respective clinical sub-cohorts was utilised. Incident hip fractures were ascertained through individual linkage to registers. Associations were investigated using multivariable Cox and linear regression analyses.

RESULTS

During up to 23 years of follow-up (mean 18.2 years) and 1,538,627 person-years at risk, 7345 participants (2840 men) experienced a hip fracture. Each daily serving of meat intake conferred a hazard ratio (HR) of 1.03 (95% confidence interval [CI] 1.00; 1.06) for hip fracture. In quintile 5, compared to quintile 2, the HR was 1.11 (95% CI 1.01; 1.21) among all participants. In the sub-cohorts, meat intake was directly associated with circulating levels of interleukin-6, C-reactive protein, leptin, ferritin, parathyroid hormone, and calcium.

CONCLUSION

A modest linear association was found between a higher meat intake and the risk of hip fractures. Our results from the sub-cohorts further suggest that possible mechanisms linking meat intake and hip fracture risk may be related to the regulation of bone turnover, subclinical inflammation, and oxidative stress. Although estimates are modest, limiting red and processed meat intake in a healthy diet is advisable to prevent hip fractures.

Dietary fatty acids and incident hip fractures in cohorts of women and men. A relative validation and follow-up study

OBJECTIVES

Hip fractures are associated with a high burden of morbidity and mortality. Diet is essential for preventing fragility fractures, but the role of dietary fatty acids on the risk of hip fracture is uncertain. The aim was to investigate how intake of different dietary fatty acids relates to the risk of hip fracture. A relative validation of the long-term intake of dietary fatty acids estimated from food frequency questionnaires (FFQs) was also performed.

DESIGN, SETTINGS AND PARTICIPANTS

We used data collected in two population-based cohorts, the Swedish Mammography Cohort and the Cohort of Swedish men (n = 83,603, 54% men, aged 45-82 years). Data from the repeated investigations in the cohorts and cross-sectional data from their clinical sub-cohorts were used.

MEASUREMENTS

Diet data was collected in FFQs. Incident hip fractures were gathered by individual linkage to national registers. We performed Cox regression analysis to investigate associations between dietary fatty acids and hip fracture. Follow-up time was between January 1st, 1998 and December 31st, 2020. The validation was performed using correlation analyses, comparing fatty acids measured in adipose tissue with estimated fatty acid intakes from FFQs.

RESULTS

During up to 23 years of follow-up (mean 18 years) and 1,538,627 person-years at risk, 7345 participants (2840 men) experienced a hip fracture. A low linoleic acid (LA) and high intakes of long-chain n-3 fatty acids were associated with higher hip fracture risk in a non-linear way. In quartile 4 compared to quartile 1 of LA, the multivariable-adjusted hazard ratio of hip fracture was 0.89 (95% Confidence Interval: 0.81, 0.97). The study confirmed the validity of FFQs to capture the intake of the specific dietary long-chain n-3 fatty acids. The estimated intake of LA, α-linolenic acid, and myristic acid were also adequately captured by the FFQs. Validity was confirmed in both women and men.

CONCLUSION

A low to moderate intake of linoleic acid and a higher intake of long-chain n-3 fatty acids were associated with a higher risk of hip fractures. The results indicate that attention should be paid to dietary fatty acid composition for the optimal prevention of fragility fractures.

Association of Dietary Vegetable and Fruit Consumption with Sarcopenia: A Systematic Review and Meta-Analysis

Previous studies have shown contradictory results regarding the association between vegetable and fruit consumption and the risk of sarcopenia. We aimed to evaluate this association using a meta-analysis, following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. We searched PubMed, EMBASE, and the Cochrane Library through July 2023 using related keywords. Pooled odds ratios (ORs) with 95% confidence intervals (CIs) were calculated based on the random-effects model. We included 14 observational studies with 11 cross-sectional and three cohort studies involving 6436 sarcopenias among 33,801 participants. Vegetable and fruit consumption were significantly associated with reduced sarcopenia risk (OR, 0.61; 95% CI, 0.48 to 0.79; I2 = 59.8%). The association was significant in cross-sectional studies (OR, 0.64; 95% CI, 0.49 to 0.84; I2 = 56.3%; n = 11) but not in cohort studies (OR, 0.50; 95% CI, 0.22 to 1.11; I2 = 76.4%; n = 3). Moreover, the association was significant in age ≥60 (OR, 0.64; 95% CI, 0.49 to 0.83; I2 = 58.0%; n = 10). This meta-analysis suggests that eating vegetables and fruit reduces sarcopenia risk. However, as cohort studies provide a higher level of evidence than case-control studies, further prospective cohort studies should be conducted.

Cornflower Extract and Its Active Components Alleviate Dexamethasone-Induced Muscle Wasting by Targeting Cannabinoid Receptors and Modulating Gut Microbiota

Sarcopenia, a decline in muscle mass and strength, can be triggered by aging or medications like glucocorticoids. This study investigated cornflower (Centaurea cyanus) water extract (CC) as a potential protective agent against DEX-induced muscle wasting in vitro and in vivo. CC and its isolated compounds mitigated oxidative stress, promoted myofiber growth, and boosted ATP production in C2C12 myotubes. Mechanistically, CC reduced protein degradation markers, increased mitochondrial content, and activated protein synthesis signaling. Docking analysis suggested cannabinoid receptors (CB) 1 and 2 as potential targets of CC compounds. Specifically, graveobioside A from CC inhibited CB1 and upregulated CB2, subsequently stimulating protein synthesis and suppressing degradation. In vivo, CC treatment attenuated DEX-induced muscle wasting, as evidenced by enhanced grip strength, exercise performance, and modulation of muscle gene expression related to differentiation, protein turnover, and exercise performance. Moreover, CC enriched gut microbial diversity, and the abundance of Clostridium sensu stricto 1 positively correlated with muscle mass. These findings suggest a multifaceted mode of action for CC: (1) direct modulation of the muscle cannabinoid receptor system favoring anabolic processes and (2) indirect modulation of muscle health through the gut microbiome. Overall, CC presents a promising therapeutic strategy for preventing and treating muscle atrophy.

Does Dietary Intake Differ in Kidney Failure Patients With Sarcopenia and Frailty Treated by Hemodialysis

Background: Inadequate nutrition is common for both sarcopenia and frailty. We investigated whether hemodialysis patients with sarcopenia and frailty have reduced dietary intakes. Methods: Dietary intake, and physical activity were analyzed, along with body composition and relevant clinical data. Results: We studied 51 hemodialysis patients; 52.9% male, age 60 ± 15 years; 33.3% sarcopenic, and 72.5% frail. Dietary protein and calories were similar for sarcopenic and non-sarcopenic patients 0.68 (0.38-3.5) vs. 0.68 (0.18-2.9) g protein/kg/day and 19.2 (8.2-77.5) vs. 15.2 (6.2-38.5) kcal/kg/day. More sarcopenic patients had low physical activity (88.2% vs. 58.8%, X2 4.6, p = .03). Frail and non-frail patients had similar intakes 0.67 (0.28-3.5) versus 0.83 (0.18-1.6) g protein/kg/day and 15.5 (8.1-77.5) vs. 18.8 (6.2-45.4) kcal/kg/day. Sarcopenia was associated with age [Odds ratio (OR) 1.09, 95% confidence interval (CI) [1.02, 1.18], p = .017], body mass index [OR 0.84, 95% CI [0.71, 0.99], p = .042] and lack of exercise [OR 7.62, 95% CI [1.16, 50.29], p = .035]. Frailty was associated with female gender [OR 17.79, 95% CI [2.09, 151.59], p = .008], age [OR 1.13, 95% CI [1.04, 1.22], p = .006], and dialysis vintage [OR 1.55, 95% CI [1.06, 2.26], p = .024]. Conclusion: Hemodialysis patients with sarcopenia and frailty did not have lower dietary protein and calorie intake. Frailty was associated with age and sarcopenia with a sedentary lifestyle.

Implementation and Core Components of a Multimodal Program including Exercise and Nutrition in Prevention and Treatment of Frailty in Community-Dwelling Older Adults: A Narrative Review

Increasing disability-free life expectancy is a crucial issue to optimize active ageing and to reduce the burden of evitable medical costs. One of the main challenges is to develop pragmatic and personalized prevention strategies in order to prevent frailty, counteract adverse outcomes such as falls and mobility disability, and to improve quality of life. Strong evidence reports the effectiveness of exercise interventions to improve various physical parameters and muscle function that are cornerstones of frailty. Other findings also suggest that the interactions between nutrition and physical exercise with or without health behavior promotion prevent the development of frailty. Multimodal programs, including structured exercise, adequate dietary intervention and health behavior promotion, appear increasingly consensual. However, in order for implementation in real-life settings, some pitfalls need to be addressed. In this perspective, structuring and tailoring feasible, acceptable and sustainable interventions to optimize exercise training responses are essential conditions to warrant short, medium and long-term individual benefits. The different components of exercise programs appear to be fairly consensual and effective. However, specific composition of the programs proposed (frequency, intensity, type, time, volume and progressiveness) have to be tailored to individual characteristics and objectives in order to improve exercise responses. The intervention approaches, behavioral strategies and indications for these programs also need to be refined and framed. The main objective of this work is to guide the actions of healthcare professionals and enable them to widely and effectively implement multimodal programs including exercise, nutrition and behavioral strategies in real-life settings.

Review article: Putting some muscle into sarcopenia-the pathogenesis, assessment and clinical impact of muscle loss in patients with inflammatory bowel disease

BACKGROUND

Sarcopenia, a loss of skeletal muscle mass or function, affects up to 50% of patients with inflammatory bowel disease (IBD) and is associated with poor clinical outcomes including increased hospitalizations, need for surgery and post-operative complications. Despite the high prevalence and clinical significance of sarcopenia in patients with IBD, few patients undergo routine muscle evaluation.

AIM

The goal of this study was to review the mechanisms of sarcopenia in patients with IBD and understand novel modalities to assess and treat impaired muscle mass or function.

METHODS

Pubmed and Cochrane databases were searched including articles published up to February 2023 utilizing the following keywords: "inflammatory bowel disease", "IBD", "Crohn's disease", "ulcerative colitis", "sarcopenia", "myosteatosis", "muscle health", and "frailty".

RESULTS

The pathogenesis of sarcopenia in IBD is not well defined, however, there is evidence supporting the role of malabsorption, reduced protein intake, chronic inflammation, dysbiosis, decreased physical activity, medication effects and hormone signaling from visceral adiposity. Traditional sarcopenia assessment techniques include direct measurements on cross sectional imaging. However, given the time, cost and radiation exposure associated with cross sectional imaging, new bedside tools are now available to estimate muscle mass, including assessment of grip strength, mid upper arm circumference and body composition utilizing bioelectrical impedance analysis. In addition, novel biomarkers for assessing muscle mass and techniques utilizing point of care ultrasound have been proposed to make sarcopenia evaluation more streamlined in the IBD clinic.

CONCLUSION

Sarcopenia is associated with poor clinical outcomes independent of IBD activity and therefore muscle health should be assessed in all IBD patients at routine intervals. Future studies to better our understanding of the pathophysiology as well as most effective management of sarcopenia in IBD will help guide clinical care and reduce disease related complications.

Association between dietary intake of α-tocopherol and cadmium related osteoporosis in population ≥ 50 years

INTRODUCTION

To analyze the association between α-tocopherol intake and cadmium (Cd) exposure and osteoporosis in population ≥ 50 years.

MATERIALS AND METHODS

Sociodemographic data, physical examination, and laboratory indicators including serum Cd level and dietary α-tocopherol intake of 8459 participants were extracted from the National Health and Nutrition Examination Survey (NHANES) database in this cross-sectional study. The associations between α-tocopherol intake, serum Cd levels and osteoporosis were evaluated using univariate and multivariate logistic regression analyses, with the estimated value (β), odds ratios (ORs) and 95% confidence intervals (CIs). We further explored the impact of α-tocopherol intake on Cd exposure and the bone mineral density (BMD) in total femur and femur neck.

RESULTS

A total of 543 old adults suffered from osteoporosis. The serum Cd level (0.52 μg/L vs. 0.37 μg/L) and α-tocopherol intake (5.28 mg vs. 6.50 mg) were statistical different in osteoporosis group and non-osteoporosis group, respectively. High level of Cd exposure was related to the increased risk of osteoporosis [OR = 1.60, 95% CI (1.15-2.21)]. In the total femur, α-tocopherol intake may improve the loss of BMD that associated with Cd exposure [β = - 0.047, P = 0.037]. Moreover, high α-tocopherol intake combined with low Cd exposure [OR = 0.54, 95% CI (0.36-0.81)] was linked to the decreased risk of osteoporosis comparing with low α-tocopherol intake combined with high Cd exposure.

CONCLUSION

High α-tocopherol intake may improve the Cd-related osteoporosis and loss of BMD that could provide some dietary reference for prevention of osteoporosis in population ≥ 50 years old.

BMP-7 Attenuates Sarcopenia and Adverse Muscle Remodeling in Diabetic Mice via Alleviation of Lipids, Inflammation, HMGB1, and Pyroptosis

Diabetic myopathy involves hyperglycemia, oxidative stress, and inflammation. However, the role of hypercholesterolemia-induced inflammation-mediated pathological mechanisms leading to fibrosis, sarcopenia, deterioration of muscle, and muscle dysfunction in diabetes is not well understood. In this study, we investigated the novel role of bone morphogenetic protein-7 (BMP-7) in ameliorating metabolic alterations, inflammation, pyroptosis, TGF-β/SMAD cell signaling mechanisms, and progression of diabetic myopathy. C57BL/6J mice were treated with saline, streptozotocin (STZ), or STZ+BMP-7. Diabetes was confirmed by increased fasting glucose levels and a glucose tolerance test. Gastrocnemius muscle and blood samples were collected for lipid and tissue analysis using various methods. A significant increase in hyperglycemia resulted in an increase in lipid accumulation, monocyte infiltration, and inflammation, as well as an increase in pyroptotic markers and signaling markers in diabetic muscle myocytes. A structural analysis showed significant muscle loss, and increased muscle deterioration and fibrosis leading to muscle dysfunction. BMP-7 attenuated pathological processes that resulted in significantly improved muscle function. We report, for the first time, that increased hyperlipidemia aggravates inflammation-induced pyroptosis, resulting in significant muscle loss, sarcopenia, and adverse skeletal muscle remodeling in diabetic muscle myopathy. Interventional treatment with BMP-7 attenuates hypercholesterolemia-induced inflammation-mediated sarcopenia and adverse muscle remodeling, suggesting BMP-7 could be a potential treatment option for diabetic muscle myopathy.

Metabolomic profiles to explore biomarkers of severe sarcopenia in older men: A pilot study

BACKGROUND

The pathophysiology of sarcopenia is complex and multifactorial; however, it has not yet been fully elucidated. Identifying metabolomic profiles may help clarify the mechanisms underlying sarcopenia.

OBJECTIVE

This pilot study explored potential noninvasive biomarkers of severe sarcopenia through metabolomic analysis in community-dwelling older men.

METHODS

Twenty older men (mean age: 81.9 ± 2.8 years) were selected from the Korean Frailty and Aging Cohort Study. Participants with severe sarcopenia (n = 10) were compared with non-sarcopenic, age- and body mass index-matched controls (n = 10). Severe sarcopenia was defined as low muscle mass, low muscle strength, and low physical performance using the Asian Working Group for Sarcopenia 2019 criteria. Non-targeted metabolomic profiling of plasma metabolites was performed using capillary electrophoresis time-of-flight mass spectrometry and absolute quantification was performed in target metabolites.

RESULTS

Among 191 plasma metabolic peaks, the concentrations of 10 metabolites significantly differed between severe sarcopenia group and non-sarcopenic controls. The plasma concentrations of L-alanine, homocitrulline, N-acetylserine, gluconic acid, N-acetylalanine, proline, and sulfotyrosine were higher, while those of 4-methyl-2-oxovaleric acid, 3-methyl-2-oxovaleric acid, and tryptophan were lower in participants with severe sarcopenia than in non-sarcopenic controls (all, p < 0.05). Among the 53 metabolites quantified as target metabolites, L-alanine (area under the receiver operating characteristic curve [AUC] = 0.760; p = 0.049), gluconic acid (AUC = 0.800; p = 0.023), proline (AUC = 0.785; p = 0.031), and tryptophan (AUC = 0.800; p = 0.023) determined the presence of severe sarcopenia.

CONCLUSIONS

Plasma metabolomic analysis demonstrated that L-alanine, gluconic acid, proline, and tryptophan may be potential biomarkers of severe sarcopenia. The identified metabolites can provide new insights into the underlying pathophysiology of severe sarcopenia and serve as the basis for preventive interventions.

An Overview of Physical Exercise and Antioxidant Supplementation Influences on Skeletal Muscle Oxidative Stress

One of the essential injuries caused by moderate to high-intensity and short-duration physical activities is the overproduction of reactive oxygen species (ROS), damaging various body tissues such as skeletal muscle (SM). However, ROS is easily controlled by antioxidant defense systems during low to moderate intensity and long-term exercises. In stressful situations, antioxidant supplements are recommended to prevent ROS damage. We examined the response of SM to ROS generation during exercise using an antioxidant supplement treatment strategy in this study. The findings of this review research are paradoxical due to variances in antioxidant supplements dose and duration, intensity, length, frequency, types of exercise activities, and, in general, the lack of a regular exercise and nutrition strategy. As such, further research in this area is still being felt.

Association Between Vitamin E and Handgrip Strength in the Korean General Population in KNHANES VII (2018)

Objective

To investigate the association between vitamin E and handgrip strength (HGS) with multiple factors.

Methods

A total of 1,814 participants were included (822 men and 981 women) from the Korean subjects of the 7th Korea National Health and Nutrition Examination Survey in 2018. Data were analyzed using multiple logistic regression to determine the correlation between vitamin E and HGS with potential confounding factors.

Results

In the multiple logistic regression model, only the young age group (19–40 years) of men showed a positive relationship between vitamin E and HGS. However, in older age groups (41–80 years) of men and all age groups of women, there was no statistically significant result. After adjusting for confounding factors, young men showed higher vitamin E levels and higher HGS. Conversely, women and older age groups did not show significant results after adjusting for confounding factors.

Conclusion

In this study, the serum vitamin E level had a positive effect on HGS in young men (<40 years). Further research is needed on this topic regarding vitamin E intake and other objective measures.

Circulating Alpha-Tocopherol Levels, Bone Mineral Density, and Fracture: Mendelian Randomization Study

Recent cohort studies indicate a potential role of the antioxidant α-tocopherol in reducing bone loss and risk of fractures, especially hip fractures. We performed a Mendelian randomization investigation of the associations of circulating α-tocopherol with estimated bone mineral density (eBMD) using heel ultrasound and fractures, identified from hospital records or by self-reports and excluding minor fractures. Circulating α-tocopherol was instrumented by three genetic variants associated with α-tocopherol levels at p < 5 × 10^-8 in a genome-wide association meta-analysis of 7781 participants of European ancestry. Summary-level data for the genetic associations with eBMD in 426,824 individuals and with fracture (53,184 cases and 373,611 non-cases) were acquired from the UK Biobank. Two of the three genetic variants were strongly associated with eBMD. In inverse-variance weighted analysis, a genetically predicted one-standard-deviation increase of circulating α-tocopherol was associated with 0.07 (95% confidence interval, 0.05 to 0.09) g/cm² increase in BMD, which corresponds to a >10% higher BMD. Genetically predicted circulating α-tocopherol was not associated with odds of any fracture (odds ratio 0.97, 95% confidence interval, 0.91 to 1.05). In conclusion, our results strongly strengthen a causal link between increased circulating α-tocopherol and greater BMD. Both an intervention study in those with a low dietary intake of α-tocopherol is warranted and a Mendelian randomization study with fragility fractures as an outcome.

Micronutrients and sarcopenia: current perspectives

Sarcopenia, a skeletal muscle disorder that is characterised by loss of muscle strength and mass, is common in older populations and associated with poorer health outcomes. Although the individual and economic costs of sarcopenia are widely recognised, current understanding of its pathophysiology is incomplete, limiting efforts to translate research evidence into effective preventive and treatment strategies. While nutrition is a key field of sarcopenia research, the role of differences in habitual diets, and the effectiveness of dietary change as a prevention or treatment strategy, is uncertain. There is a growing evidence base that links low micronutrient intakes to sarcopenia risk and/or its components (low muscle strength and mass, impaired physical performance), although there remain many gaps in understanding. There is some consistency in findings across studies highlighting potential roles for antioxidant nutrients, B vitamins and magnesium; however, the evidence is largely observational and from cross-sectional studies, often describing associations with different muscle outcomes. As low intakes of some micronutrients are common in older populations, there is a need for new research, particularly from well-characterised prospective cohorts, to improve the understanding of their role and importance in the aetiology of sarcopenia and to generate the evidence needed to inform dietary guidelines to promote muscle health.

Lower Dietary and Circulating Vitamin C in Middle- and Older-Aged Men and Women Are Associated with Lower Estimated Skeletal Muscle Mass

BACKGROUND

Age-related loss of skeletal muscle mass contributes to poor outcomes including sarcopenia, physical disability, frailty, type 2 diabetes, and mortality. Vitamin C has physiological relevance to skeletal muscle and may protect it during aging, but few studies have investigated its importance in older populations.

OBJECTIVES

We aimed to investigate cross-sectional associations of dietary and plasma vitamin C with proxy measures of skeletal muscle mass in a large cohort of middle- and older-aged individuals.

METHODS

We analyzed data from >13,000 men and women in the European Prospective Investigation into Cancer and Nutrition-Norfolk cohort, aged 42-82 y. Fat-free mass (FFM), as a proxy for skeletal muscle mass, was estimated using bioelectrical impedance analysis and expressed as a percentage of total mass (FFM%) or standardized by BMI (FFMBMI). Dietary vitamin C intakes were calculated from 7-d food diary data, and plasma vitamin C was measured in peripheral blood. Multivariable regression models, including relevant lifestyle, dietary, and biological covariates, were used to determine associations between FFM measures and quintiles of dietary vitamin C or insufficient compared with sufficient plasma vitamin C (<50 μmol/L and ≥50 μmol/L).

RESULTS

Positive trends were found across quintiles of dietary vitamin C and FFM measures for both sexes, with interquintile differences in FFM% and FFMBMI of 1.0% and 2.3% for men and 1.9% and 2.9% for women, respectively (all P < 0.001). Similarly, FFM% and FFMBMI measures were higher in participants with sufficient than with insufficient plasma vitamin C: by 1.6% and 2.0% in men, and 3.4% and 3.9% in women, respectively (all P < 0.001). Associations were also evident in analyses stratified into <65-y and ≥65-y age groups.

CONCLUSIONS

Our findings of positive associations, of both dietary and circulating vitamin C with measures of skeletal muscle mass in middle- and older-aged men and women, suggest that dietary vitamin C intake may be useful for reducing age-related muscle loss.

Nutrition and microRNAs: Novel Insights to Fight Sarcopenia

Sarcopenia is a progressive age-related loss of skeletal muscle mass and strength, which may result in increased physical frailty and a higher risk of adverse events. Low-grade systemic inflammation, loss of muscle protein homeostasis, mitochondrial dysfunction, and reduced number and function of satellite cells seem to be the key points for the induction of muscle wasting, contributing to the pathophysiological mechanisms of sarcopenia. While a range of genetic, hormonal, and environmental factors has been reported to contribute to the onset of sarcopenia, dietary interventions targeting protein or antioxidant intake may have a positive effect in increasing muscle mass and strength, regulating protein homeostasis, oxidative reaction, and cell autophagy, thus providing a cellular lifespan extension. MicroRNAs (miRNAs) are endogenous small non-coding RNAs, which control gene expression in different tissues. In skeletal muscle, a range of miRNAs, named myomiRNAs, are involved in many physiological processes, such as growth, development, and maintenance of muscle mass and function. This review aims to present and to discuss some of the most relevant molecular mechanisms related to the pathophysiological effect of sarcopenia. Besides, we explored the role of nutrition as a possible way to counteract the loss of muscle mass and function associated with ageing, with special attention paid to nutrient-dependent miRNAs regulation. This review will provide important information to better understand sarcopenia and, thus, to facilitate research and therapeutic strategies to counteract the pathophysiological effect of ageing.

Is a Healthy Diet Also Suitable for the Prevention of Fragility Fractures?

Osteoporosis and sarcopenia contribute to the risk of fracture in the population. These conditions share common features, and it is known that a healthy diet may have beneficial effects on both, theoretically resulting in fewer fractures. The present narrative review gives an overview of recent epidemiological research related to the association between healthy diets/dietary patterns, bone health and fragility fractures. The review also gives a brief overview on general dietary recommendations and advice as the cornerstone of public health nutrition. Although muscle health and sarcopenia contribute to the risk of fractures, these endpoints were not the focus of this review. Healthy diets are nutrient dense and contain bioactive components that are needed for the constant remodeling of the skeleton and to slow the rate of bone loss and muscle wasting, thus contributing to the prevention of fragility fractures. Compliance with healthy dietary patterns were predominantly found to be inversely associated with bone outcomes, although this was not entirely consistent across all studies. Different a priori diet scores, such as the Mediterranean diet score and the Dietary Inflammatory Index, as well as a posteriori data driven dietary patterns, such as the prudent or healthy dietary pattern, were inversely associated with fragility fractures in different populations. In conclusion, different healthy dietary patterns may contribute to bone health and less fractures. Following current dietary guidelines is thus advisable for the prevention of fragility fractures.

Structural and Functional Changes in the Coupling of Fascial Tissue, Skeletal Muscle, and Nerves During Aging

Aging is a one-way process associated with profound structural and functional changes in the organism. Indeed, the neuromuscular system undergoes a wide remodeling, which involves muscles, fascia, and the central and peripheral nervous systems. As a result, intrinsic features of tissues, as well as their functional and structural coupling, are affected and a decline in overall physical performance occurs. Evidence from the scientific literature demonstrates that senescence is associated with increased stiffness and reduced elasticity of fascia, as well as loss of skeletal muscle mass, strength, and regenerative potential. The interaction between muscular and fascial structures is also weakened. As for the nervous system, aging leads to motor cortex atrophy, reduced motor cortical excitability, and plasticity, thus leading to accumulation of denervated muscle fibers. As a result, the magnitude of force generated by the neuromuscular apparatus, its transmission along the myofascial chain, joint mobility, and movement coordination are impaired. In this review, we summarize the evidence about the deleterious effect of aging on skeletal muscle, fascial tissue, and the nervous system. In particular, we address the structural and functional changes occurring within and between these tissues and discuss the effect of inflammation in aging. From the clinical perspective, this article outlines promising approaches for analyzing the composition and the viscoelastic properties of skeletal muscle, such as ultrasonography and elastography, which could be applied for a better understanding of musculoskeletal modifications occurring with aging. Moreover, we describe the use of tissue manipulation techniques, such as massage, traction, mobilization as well as acupuncture, dry needling, and nerve block, to enhance fascial repair.

Lactobacillus paracasei PS23 decelerated age-related muscle loss by ensuring mitochondrial function in SAMP8 mice

Sarcopenia is a common impairment in the elderly population responsible for poor outcomes later in life; it can be caused by age-related alternations. Only a few strategies have been reported to reduce sarcopenia. Lactobacillus paracasei PS23 (LPPS23) has been reported to delay some age-related disorders. Therefore, here we investigated whether LPPS23 decelerates age-related muscle loss and its underlying mechanism. Female senescence-accelerated mouse prone-8 (SAMP8) mice were divided into three groups (n=6 each): non-aging (16-week-old), control (28-week-old), and PS23 (28-week-old) groups. The control and PS23 groups were given saline and LPPS23, respectively. We evaluated the effects of LPPS23 by analyzing body weight and composition, muscle strength, protein uptake, mitochondrial function, reactive oxygen species (ROS), antioxidant enzymes, and inflammation-related cytokines. LPPS23 significantly attenuated age-related decreases of muscle mass and strength. Compared to the control group, the non-aging and PS23 groups exhibited higher mitochondrial function, IL10, antioxidant enzymes, and protein uptake. Moreover, inflammatory cytokines and ROS were lower in the non-aging and PS23 groups than the control group. Taken together, LPPS23 extenuated sarcopenia progression during aging; this effect might have been enacted by preserving the mitochondrial function via reducing age-related inflammation and ROS and by retaining protein uptake in the SAMP8 mice.

Nutrition and Muscle Strength, As the Key Component of Sarcopenia: An Overview of Current Evidence

Much has been achieved by recent research to increase understanding of the links between nutrition and muscle health. Focusing on muscle strength as the key component of sarcopenia, the aim of this overview was to evaluate its links to nutrition, both to variation in habitual diets in older populations, as well as considering supplementation effects in trials. A main message from the reviewed studies is that while many provide suggestive evidence of benefits of higher nutrient intakes and diets of higher quality, findings are inconsistent, and data on muscle strength are often lacking. To assess the potential of optimising diets as a strategy to promote and maintain muscle strength, gaps in current evidence need to be addressed. These include the need for (i) better understanding of individual differences in responsiveness to dietary change, and the need for targeted nutritional support; (ii) clearer distinction between protective and therapeutic actions of diet; and (iii) definition of the role of dietary patterns and their influence on muscle strength, to allow effects of changes in food consumption to be evaluated—particularly when combined with physical activity. Development of this evidence is needed to enable translation into appropriate dietary recommendations for older populations.

Dual Role of Reactive Oxygen Species in Muscle Function: Can Antioxidant Dietary Supplements Counteract Age-Related Sarcopenia?

Sarcopenia is characterized by the progressive loss of skeletal muscle mass and strength. In older people, malnutrition and physical inactivity are often associated with sarcopenia, and, therefore, dietary interventions and exercise must be considered to prevent, delay, or treat it. Among the pathophysiological mechanisms leading to sarcopenia, a key role is played by an increase in reactive oxygen and nitrogen species (ROS/RNS) levels and a decrease in enzymatic antioxidant protection leading to oxidative stress. Many studies have evaluated, in addition to the effects of exercise, the effects of antioxidant dietary supplements in limiting age-related muscle mass and performance, but the data which have been reported are conflicting. In skeletal muscle, ROS/RNS have a dual function: at low levels they increase muscle force and adaptation to exercise, while at high levels they lead to a decline of muscle performance. Controversial results obtained with antioxidant supplementation in older persons could in part reflect the lack of univocal effects of ROS on muscle mass and function. The purpose of this review is to examine the molecular mechanisms underlying the dual effects of ROS in skeletal muscle function and the analysis of literature data on dietary antioxidant supplementation associated with exercise in normal and sarcopenic subjects.

Metabolic and Molecular Basis of Sarcopenia: Implications in the Management of Urothelial Carcinoma

Sarcopenia, which represents the degenerative and systemic loss of skeletal muscle mass, is a multifactorial syndrome caused by various clinical conditions. Sarcopenia reflects not only frailty and poor general health status, but also the possible presence of advanced or progressive cancer or cancer cachexia. Therefore, sarcopenia affects the management of cancer-bearing patients, including those with urothelial carcinoma. Recently, growing evidence has shown that sarcopenia is significantly associated with higher rates of treatment-related complications and worse prognosis in patients with urothelial carcinoma, including muscle-invasive bladder cancer, upper tract urothelial carcinoma, and advanced urothelial carcinoma. Moreover, several studies reported that a post-therapeutic increase in skeletal muscle mass predicts favorable prognosis in urothelial carcinoma patients. To further explore the role of sarcopenia in the management of urothelial carcinoma patients, comprehensive understanding of its pathophysiology is vital. In this article, we reviewed the metabolic and molecular basis of cancer cachexia and sarcopenia. From this viewpoint, we discussed the possible mechanism of changes in skeletal muscle mass during the course of treatment.

High Tomato and Tomato Product Consumption is Protective Against the Decline in Handgrip Strength Among Japanese Adults: The Oroshisho Study

Background

There is scarce epidemiological evidence regarding the relationships of the consumption of different types of vegetables or fruits with change in skeletal muscle strength. We prospectively examined the relationships among Japanese adults, using handgrip strength to assess skeletal muscle strength.

Methods

A 3-year study was carried out with 259 Japanese adults who were 22–68 years of age. The frequency of consumption of different types of vegetables or fruits were obtained using a validated self-administered dietary history questionnaire. Handgrip strength was measured with a handheld digital Smedley dynamometer.

Results

After adjustment for confounding factors, the mean change in handgrip strength in participants stratified according to the level of tomato and tomato product consumption at baseline were −3.2 (95% confidence interval [CI], −4.0 to −2.3) for <1 time/week, −2.7 (95% CI, −3.6 to −1.8) for 1 time/week, −1.6 (95% CI, −2.5 to −0.8) for 2–3 times/week, and −1.7 (95% CI, −2.8 to −0.7) for ≥4 times/week, (P for trend = 0.022). However, the significant relationships of consumption of other types of vegetables and different types of fruits with change in handgrip strength were not observed.

Conclusion

Higher consumption of tomato and tomato product at baseline was significantly associated with reduced decline in handgrip strength among Japanese adults over a 3-year follow-up period. This study suggests that consumption of tomato and tomato product could be protective against the decline in skeletal muscle strength associated with aging.

Redox Control of Skeletal Muscle Regeneration

Skeletal muscle shows high plasticity in response to external demand. Moreover, adult skeletal muscle is capable of complete regeneration after injury, due to the properties of muscle stem cells (MuSCs), the satellite cells, which follow a tightly regulated myogenic program to generate both new myofibers and new MuSCs for further needs. Although reactive oxygen species (ROS) and reactive nitrogen species (RNS) have long been associated with skeletal muscle physiology, their implication in the cell and molecular processes at work during muscle regeneration is more recent. This review focuses on redox regulation during skeletal muscle regeneration. An overview of the basics of ROS/RNS and antioxidant chemistry and biology occurring in skeletal muscle is first provided. Then, the comprehensive knowledge on redox regulation of MuSCs and their surrounding cell partners (macrophages, endothelial cells) during skeletal muscle regeneration is presented in normal muscle and in specific physiological (exercise-induced muscle damage, aging) and pathological (muscular dystrophies) contexts. Recent advances in the comprehension of these processes has led to the development of therapeutic assays using antioxidant supplementation, which result in inconsistent efficiency, underlying the need for new tools that are aimed at precisely deciphering and targeting ROS networks. This review should provide an overall insight of the redox regulation of skeletal muscle regeneration while highlighting the limits of the use of nonspecific antioxidants to improve muscle function. Antioxid. Redox Signal. 27, 276-310.

Mediterranean Diet and Hip Fracture in Swedish Men and Women

A Mediterranean diet, known to have beneficial effects on cardiovascular health, may also influence the risk of hip fracture although previous studies present discrepant results. We therefore aimed to determine whether the rate of hip fracture was associated with degree of adherence to a Mediterranean diet. We combined two Swedish cohort studies consisting of 37,903 men and 33,403 women (total n = 71,333, mean age 60 years) free of previous cardiovascular disease and cancer who answered a medical and a food-frequency questionnaire in 1997. A modified Mediterranean diet score (mMED; range, 0 to 8 points) was created based on high consumption of fruits and vegetables, legumes and nuts, whole grains, fermented dairy products, fish, and olive/rapeseed oil, moderate intake of alcohol, and low intake of red and processed meat. Incident hip fractures between January 1, 1998, and December 31, 2012, were retrieved from the National Patient Register. Hazard ratios (HRs) and 95% confidence intervals (CIs) adjusted for potential confounders were calculated using Cox proportional hazards regression. Differences in age at hip fracture were calculated using multivariable Laplace regression. During follow-up, 3175 hip fractures occurred at a median age of 73.3 years. One unit increase in the mMED was associated with 6% lower hip fracture rate (adjusted HR = 0.94; 95% CI, 0.92 to 0.96) and with a 3-month higher median age at hip fracture (50th percentile difference = 2.8 months; 95% CI, 1.4 to 4.2). Comparing the highest quintile of adherence to the mMED (6 to 8 points) with the lowest (0 to 2 points) conferred an adjusted HR of hip fracture of 0.78 (95% CI, 0.69 to 0.89) and a 12-month higher median age of hip fracture (50th percentile difference = 11.6 months; 95% CI, 4.2 to 19.0). Results were similar in men and women. We conclude that higher adherence to a Mediterranean-like diet is associated with lower risk of future hip fracture. © 2016 American Society for Bone and Mineral Research.

Melatonin as a Potential Agent in the Treatment of Sarcopenia

Considering the increased speed at which the world population is aging, sarcopenia could become an epidemic in this century. This condition currently has no means of prevention or treatment. Melatonin is a highly effective and ubiquitously acting antioxidant and free radical scavenger that is normally produced in all organisms. This molecule has been implicated in a huge number of biological processes, from anticonvulsant properties in children to protective effects on the lung in chronic obstructive pulmonary disease. In this review, we summarize the data which suggest that melatonin may be beneficial in attenuating, reducing or preventing each of the symptoms that characterize sarcopenia. The findings are not limited to sarcopenia, but also apply to osteoporosis-related sarcopenia and to age-related neuromuscular junction dysfunction. Since melatonin has a high safety profile and is drastically reduced in advanced age, its potential utility in the treatment of sarcopenic patients and related dysfunctions should be considered.

The effects of the Pilates method in the elderly: a systematic review

Several studies show the benefits of including muscle strength and aerobic physical activity in the routine of elderly people. Among the various possibilities of physical activity, the Pilates method has become a popular modality in recent years, through a system of exercises enabling to work the whole body and that corrects posture and realigns the muscles, developing the body stability needed for a healthier life. The aim of this study was to review the current evidence on the effects of the practice of the Pilates method in the elderly. A systematic literature review was conducted in the following electronic databases: Pubmed, Scielo, Lilacs/Bireme, Scopus, Pedro and Isi of Knowledge, from descriptors pilates, elderly, old adults, aging. In the selection of studies the following inclusion criteria were used: original articles in English, Portuguese and Spanish languages. All selection and evaluation processes of the articles were performed by peers and the quality was verified by the Downs and Black scale. Twenty-one studies were included. The year of publication ranged from 2003 to 2014 and the size of the sample varied from 8 to 311 elderly subjects, aged at least 60 years old. The intervention period was from 4 weeks to 12 months of Pilates exercise practice. It was concluded that despite the studies pointing to physical and motor benefits of the Pilates method in the elderly, we cannot state whether or not the method is effective, in view of the poor methodological quality of the studies included in this review.

The effects of the Pilates method in the elderly: a systematic review

Several studies show the benefits of including muscle strength and aerobic physical activity in the routine of elderly people. Among the various possibilities of physical activity, the Pilates method has become a popular modality in recent years, through a system of exercises enabling to work the whole body and that corrects posture and realigns the muscles, developing the body stability needed for a healthier life. The aim of this study was to review the current evidence on the effects of the practice of the Pilates method in the elderly. A systematic literature review was conducted in the following electronic databases: Pubmed, Scielo, Lilacs/Bireme, Scopus, Pedro and Isi of Knowledge, from descriptors pilates, elderly, old adults, aging. In the selection of studies the following inclusion criteria were used: original articles in English, Portuguese and Spanish languages. All selection and evaluation processes of the articles were performed by peers and the quality was verified by the Downs and Black scale. Twenty-one studies were included. The year of publication ranged from 2003 to 2014 and the size of the sample varied from 8 to 311 elderly subjects, aged at least 60 years old. The intervention period was from 4 weeks to 12 months of Pilates exercise practice. It was concluded that despite the studies pointing to physical and motor benefits of the Pilates method in the elderly, we cannot state whether or not the method is effective, in view of the poor methodological quality of the studies included in this review.

Focus on Pivotal Role of Dietary Intake (Diet and Supplement) and Blood Levels of Tocopherols and Tocotrienols in Obtaining Successful Aging

Numerous specific age-related morbidities have been correlated with low intake and serum levels of tocopherols and tocotrienols. We performed a review in order to evaluate the extant evidence regarding: (1) the association between intake and serum levels of tocopherols and tocotrienols and age-related pathologies (osteoporosis, sarcopenia and cognitive impairment); and (2) the optimum diet therapy or supplementation with tocopherols and tocotrienols for the treatment of these abnormalities. This review included 51 eligible studies. The recent literature underlines that, given the detrimental effect of low intake and serum levels of tocopherols and tocotrienols on bone, muscle mass, and cognitive function, a change in the lifestyle must be the cornerstone in the prevention of these specific age-related pathologies related to vitamin E-deficient status. The optimum diet therapy in the elderly for avoiding vitamin E deficiency and its negative correlates, such as high inflammation and oxidation, must aim at achieving specific nutritional goals. These goals must be reached through: accession of the elderly subjects to specific personalized dietary programs aimed at achieving and/or maintaining body weight (avoid malnutrition); increase their intake of food rich in vitamin E, such as derivatives of oily seeds (in particular wheat germ oil), olive oil, hazelnuts, walnuts, almonds, and cereals rich in vitamin E (such as specific rice cultivar rich in tocotrienols) or take vitamin E supplements. In this case, vitamin E can be correctly used in a personalized way either for the outcome from the pathology or to achieve healthy aging and longevity without any adverse effects.

Fruit and vegetable intake and risk of hip fracture: a cohort study of Swedish men and women

Dietary guidelines recommend a daily intake of 5 servings of fruits and vegetables. Whether such intakes are associated with a lower risk of hip fracture is at present unclear. The aim of the present study was to investigate the dose-response association between habitual fruit and vegetable intake and hip fracture in a cohort study based on 40,644 men from the Cohort of Swedish Men (COSM) and 34,947 women from the Swedish Mammography Cohort (SMC) (total n = 75,591), free from cardiovascular disease and cancer, who answered lifestyle questionnaires in 1997 (age 45 to 83 years). Intake of fruits and vegetables (servings/day) was assessed by food frequency questionnaire and incident hip fractures were retrieved from the Swedish Patient Register (1998 to 2010). The mean follow-up time was 14.2 years. One-third of the participants reported an intake of fruits and vegetables of >5 servings/day, one-third reported >3 to ≤5 servings/day, 28% reported >1 to ≤3 servings/day, and 6% reported ≤1 serving/day. During 1,037,645 person-years we observed 3644 hip fractures (2266 or 62% in women). The dose-response association was found to be strongly nonlinear (p < 0.001). Men and women with zero consumption had 88% higher rate of hip fracture compared with those consuming 5 servings/day; adjusted hazard ratio (HR) was 1.88 (95% CI, 1.53 to 2.32). The rate was gradually lower with higher intakes; adjusted HR for 1 versus 5 servings/day was 1.35 (95% CI, 1.21 to 1.58). However, more than 5 servings/day did not confer additionally lower HRs (adjusted HR for 8 versus 5 servings/day was 0.96; 95% CI, 0.90 to 1.03). Similar results were observed when men and women were analyzed separately. We conclude that there is a dose-response association between fruit and vegetable intake and hip fracture such that an intake below the recommended five servings/day confers higher rates of hip fracture. Intakes above this recommendation do not seem to further lower the risk.

Association of vegetables and fruits consumption with sarcopenia in older adults: the Fourth Korea National Health and Nutrition Examination Survey

BACKGROUND

several studies have found nutrients, including antioxidants, to be associated with sarcopenia. However, whether specific foods, such as vegetables and fruits, are associated with sarcopenia has not been studied.

OBJECTIVE

to examine the association of the frequency of vegetables and fruits consumption with sarcopenia in older people.

METHODS

this study used cross-sectional data from the Fourth Korea National Health and Nutrition Examination Survey in 2008-09. Subjects were community-dwelling 823 men and 1,089 women aged ≥65 years. Frequency of food group consumption was obtained by using the food frequency questionnaire. Body composition was measured with the dual-energy X-ray absorptiometry and sarcopenia was defined as appendicular lean mass adjusted for height and fat mass. Logistic regression was used to assess the association of the frequency of food group consumption with sarcopenia, controlling for sociodemographics and health-related variables.

RESULTS

dietary intake of vegetables, fruits and both vegetables and fruits was associated with a significantly reduced risk of sarcopenia after controlling for covariates in men (P = 0.026 for trend, P = 0.012 for trend, P = 0.003 for trend, respectively). Men in the highest quintile, compared with those in the lowest quintile, of vegetables [odds ratio (OR) = 0.48; 95% confidence interval (CI): 0.24-0.95], fruits (OR = 0.30; 95% CI: 0.13-0.70) and vegetables and fruits consumption (OR = 0.32; 95% CI: 0.16-0.67) demonstrated a lower risk of sarcopenia. In women, high consumption of fruits demonstrated a lower risk of sarcopenia (OR = 0.39; 95% CI: 0.18-0.83).

CONCLUSION

frequent vegetables and fruits consumption was inversely associated with sarcopenia in older adults.

High whey protein intake delayed the loss of lean body mass in healthy old rats, whereas protein type and polyphenol/antioxidant supplementation had no effects

Our aim was to compare and combine 3 nutritional strategies to slow down the age-related loss of muscle mass in healthy old rats: 1) increase protein intake, which is likely to stimulate muscle protein anabolism; 2) use leucine rich, rapidly digested whey proteins as protein source (whey proteins are recognized as the most effective proteins to stimulate muscle protein anabolism). 3) Supplement animals with a mixture of chamomile extract, vitamin E, vitamin D (reducing inflammation and oxidative stress is also effective to improve muscle anabolism). Such comparisons and combinations were never tested before. Nutritional groups were: casein 12% protein, whey 12% protein, whey 18% protein and each of these groups were supplemented or not with polyphenols/antioxidants. During 6 months, we followed changes of weight, food intake, inflammation (plasma fibrinogen and alpha-2-macroglobulin) and body composition (DXA). After 6 months, we measured muscle mass, in vivo and ex-vivo fed and post-absorptive muscle protein synthesis, ex-vivo muscle proteolysis, and oxidative stress parameters (liver and muscle glutathione, SOD and total antioxidant activities, muscle carbonyls and TBARS). We showed that although micronutrient supplementation reduced inflammation and oxidative stress, the only factor that significantly reduced the loss of lean body mass was the increase in whey protein intake, with no detectable effect on muscle protein synthesis, and a tendency to reduce muscle proteolysis. We conclude that in healthy rats, increasing protein intake is an effective way to delay sarcopenia.

Intake and serum concentrations of α-tocopherol in relation to fractures in elderly women and men: 2 cohort studies

BACKGROUND

A reduction in the formation of free radicals and oxidative stress might reduce the rate of bone loss and muscle wasting.

OBJECTIVE

The objective was to determine whether α-tocopherol intake or serum concentrations are associated with fracture risk in older women and men.

DESIGN

Two cohort studies, the Swedish Mammography Cohort (SMC; n = 61,433 women) and the Uppsala Longitudinal Study of Adult Men (ULSAM; n = 1138 men), were used.

RESULTS

During 19 y of follow-up, 14,738 women in the SMC experienced a first fracture at any site (3871 hip fractures). A higher hip fracture rate was observed with lower intakes of α-tocopherol. Compared with the highest quintile of intake, the lowest quintile had a multivariable-adjusted HR of 1.86 (95% CI: 1.67, 2.06). The HR of any fracture was 1.20 (95% CI: 1.14, 1.28). α-Tocopherol-containing supplement use was associated with a reduced rate of hip fracture (HR: 0.78; 95% CI: 0.65, 0.93) and any fracture (HR: 0.86; 95% CI: 0.78, 0.94). Compared with the highest quintile of α-tocopherol intake in ULSAM (follow-up: 12 y), lower intakes (quintiles 1-4) were associated with a higher rate of hip fracture (HR: 3.33; 95% CI: 1.43, 7.76) and any fracture (HR: 1.84; 95% CI: 1.18, 2.88). The HR for hip fracture in men for each 1-SD decrease in serum α-tocopherol was 1.58 (95% CI: 1.13, 2.22) and for any fracture was 1.23 (95% CI: 1.02, 1.48).

CONCLUSION

Low intakes and low serum concentrations of α-tocopherol are associated with an increased rate of fracture in elderly women and men.

Protein thiol oxidation does not change in skeletal muscles of aging female mice

Oxidative stress caused by reactive oxygen species is proposed to cause age related muscle wasting (sarcopenia). Reversible oxidation of protein thiols by reactive oxygen species can affect protein function, so we evaluated whether muscle wasting in normal aging was associated with a pervasive increase in reversible oxidation of protein thiols or with an increase in irreversible oxidative damage to macromolecules. In gastrocnemius muscles of C57BL/6J female mice aged 3, 15, 24, 27, and 29 months there was no age related increase in protein thiol oxidation. In contrast, there was a significant correlation (R (2) = 0.698) between increasing protein carbonylation, a measure of irreversible oxidative damage to proteins, and loss of mass of gastrocnemius muscles in aging female mice. In addition, there was an age-related increase in lipofuscin content, an aggregate of oxidised proteins and lipids, in quadriceps limb muscles in aging female mice. However, there was no evidence of an age-related increase in malondialdehyde or F2-isoprostanes levels, which are measures of oxidative damage to lipids, in gastrocnemius muscles. In summary, this study does not support the hypothesis that a pervasive increase in protein thiol oxidation is a contributing factor to sarcopenia. Instead, the data are consistent with an aging theory which proposes that molecular damage to macromolecules leads to the structural and functional disorders associated with aging.

Mitochondrial dysfunction and sarcopenia of aging: from signaling pathways to clinical trials

Sarcopenia, the age-related loss of muscle mass and function, imposes a dramatic burden on individuals and society. The development of preventive and therapeutic strategies against sarcopenia is therefore perceived as an urgent need by health professionals and has instigated intensive research on the pathophysiology of this syndrome. The pathogenesis of sarcopenia is multifaceted and encompasses lifestyle habits, systemic factors (e.g., chronic inflammation and hormonal alterations), local environment perturbations (e.g., vascular dysfunction), and intramuscular specific processes. In this scenario, derangements in skeletal myocyte mitochondrial function are recognized as major factors contributing to the age-dependent muscle degeneration. In this review, we summarize prominent findings and controversial issues on the contribution of specific mitochondrial processes - including oxidative stress, quality control mechanisms and apoptotic signaling - on the development of sarcopenia. Extramuscular alterations accompanying the aging process with a potential impact on myocyte mitochondrial function are also discussed. We conclude with presenting methodological and safety considerations for the design of clinical trials targeting mitochondrial dysfunction to treat sarcopenia. Special emphasis is placed on the importance of monitoring the effects of an intervention on muscle mitochondrial function and identifying the optimal target population for the trial. This article is part of a Directed Issue entitled: Molecular basis of muscle wasting.