Vitamin D and its role in skeletal muscle

An Overview of Sarcopenia: Focusing on Nutritional Treatment Approaches

Sarcopenia is a syndrome characterized by the progressive and generalized loss of skeletal muscle mass and strength. This condition is associated with physical disability, decreased quality of life, and increased mortality. Therefore, reducing the prevalence of sarcopenia could significantly lower healthcare costs. Sarcopenia can be classified into primary and secondary sarcopenia. The former is related to aging and begins after the fourth decade of life; after that, there is a muscle loss of around 8% per decade until age 70 years, which subsequently increases to 15% per decade. On the other hand, secondary sarcopenia can affect all individuals and may result from various factors including physical inactivity, malnutrition, endocrine disorders, neurodegenerative diseases, inflammation, and cachexia. Understanding the multiple mechanisms involved in the onset and progression of sarcopenia allows for us to develop strategies that can prevent, treat, or at least mitigate muscle loss caused by increased protein breakdown. One potential treatment of sarcopenia is based on nutritional interventions, including adequate caloric and protein intake and specific nutrients that support muscle health. Such nutrients include natural food rich in whey protein and omega-3 fatty acids as well as nutritional supplements like branched-chain amino acids, β-hydroxy-β-methylbutyrate, and vitamin D along with food for special medical purposes. It is important to emphasize that physical exercises, especially resistance training, not only promote muscle protein synthesis on their own but also work synergistically with nutritional strategies to enhance their effectiveness.

Mesenchymal stem cell-specific Sirt1 overexpression prevents sarcopenia induced by 1,25-dihydroxyvitamin D deficiency

Sarcopenia, characterized by an age-related decline in skeletal muscle mass and function, is closely linked to vitamin D deficiency. This study examines the role of Sirtuin 1 (Sirt1) and its regulation by vitamin D in preventing sarcopenia. Utilizing wild-type, 1α-hydroxylase knockout (1α(OH)ase-/-), and Sirt1 transgenic (Sirt1Tg) 1α(OH)ase-/- mice, we investigated muscle Sirt1 levels, muscle mass, fiber type, and senescence markers. Our results demonstrated that 1,25-Dihydroxyvitamin D (1,25(OH)2D3) upregulated Sirt1 and myogenic factor MyoD1 expression in C2C12 myoblasts via VDR-mediated transcription. Sirt1 overexpression in mesenchymal stem cells (MSCs) significantly mitigated muscle mass reduction, improved fiber cross-sectional area, and increased type II fiber numbers in 1α(OH)ase-/- mice. Mechanistically, 1,25(OH)2D3 promoted muscle cell health by enhancing Sirt1 expression, which in turn reduced muscle cell senescence and the senescence-associated secretory phenotype (SASP) through decreased levels of acetylated nuclear p53 and p65, maintaining their cytoplasmic localization. Additionally, Sirt1 overexpression accelerated muscle regeneration post-injury by increasing embryonic myosin heavy chain expression and cell proliferation. These findings underscore the therapeutic potential of targeting vitamin D and Sirt1 pathways to prevent sarcopenia, suggesting that supplementation with active vitamin D and consequent Sirt1 activation could be effective strategies for managing age-related muscle wasting.

Effects of High-Dose Vitamin D3 Supplementation on Pig Performance, Vitamin D Content in Meat, and Muscle Transcriptome in Pigs

Vitamin D is known for its role in calcium homeostasis, bone health, and immune function. Recent research has explored its effects on muscle functionality and meat quality in pigs. This study examined high-dose vitamin D3 supplementation in pigs, focusing on growth, blood and tissue vitamin D3 levels, and muscle transcriptome changes. Thirty pigs were divided into three groups, given different amounts of oral supplementation: control, 5000 IU/kg and 10,000 IU/kg vitamin D3. Biochemical and haematological blood parameters, vitamin D content in blood and muscle, and kidney calcium content were evaluated. RNA-seq and qPCR analysed muscle transcriptome changes, while gene set enrichment analysis (GSEA) identified gene expression enrichments. Results showed that 5000 IU/kg vitamin D3 supplementation altered blood parameters like platelet anisocytosis and glucose levels but did not affect body weight, weight gain, or feed intake. Kidney calcium content increased with supplementation. The muscle (longissimus dorsi) vitamin D content increased, suggesting the potential for biofortified pork, although still not optimal as a dietary vitamin D source. Transcriptome analysis revealed minimal gene expression changes, with only the interferon-gamma receptor 2 (IFNGR2) gene differentially expressed at the highest dose. GSEA indicated enrichment in ATP metabolic processes and electron transport chain genes in the 5000 IU/kg group, and immune system, cholesterol, steroid, and fatty acid metabolism genes in the 10,000 IU/kg group. Despite literature suggesting a role for vitamin D in muscle gene expression and growth improvement, this study found its effects limited.

Efficacy of different nutrition interventions on sarcopenia in patients with cirrhosis: a systematic review and network meta-analysis

BACKGROUND & AIMS

Sarcopenia, characterized by the loss of muscle mass and strength, is a significant concern in cirrhotic patients. Nutritional interventions have been explored for its management, but the comparative efficacy of these interventions remains unclear. This study synthesizes current evidence to evaluate the effectiveness of nutritional interventions for sarcopenia in cirrhosis.

METHODS

Data sources included Scopus, PubMed, Web of Science Core Collection, and Cochrane Library up to Dec 2024. Eligible trials compared different nutritional interventions against control diets, placebos, or each other. A Bayesian network meta-analysis was performed to combine direct and indirect evidence. Effect sizes were calculated as mean differences (MD) with 95% confidence intervals (CIs). Intervention rankings were assessed using P-score, and evidence quality was evaluated using the Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) approach.

RESULTS

A total of 14 randomized controlled trials (RCTs) involving 1,437 patients met the inclusion criteria. For improving muscle mass (MAMC), post-paracentesis intravenous nutritional support combined with an oral nutritional protocol (Treat A) showed the greatest effect compared to high-calorie, high-protein diets (HCHP) (MD: 2.78 cm, 95% CI: 1.15 to 4.40, low certainty), and oral nutritional protocol (Treat B) (MD of 3.41 cm, 95% CI: 2.12, 4.69). For muscle strength, the HINT diet (MD: 8.01 kg, 95% CI: 7.64 to 8.37, low certainty) and the HCHP (MD: 5 kg, 95% CI: 3.90 to 6.10, low certainty) were more effective than control diets. HCHP also demonstrated greater handgrip improvement than the HINT diet (MD: 3.00 kg, 95% CI: 1.84, 4.16; low certainty evidence). BCAA combined with vitamin D (2000 IU once a day) significantly improved skeletal muscle index (SMI) compared to both BCAA (MD: 0.72 kg/m2, 95% CI: 0.11 to 1.34; low certainty evidence) and placebo (MD: 0.25 kg/m2, 95% CI: -0.05 to 0.05; very low certainty evidence). BCAA supplementation effectively improved handgrip strength compared to placebo (MD: 2.36 kg, 95% CI: 1.85, 2.88; low certainty evidence).

CONCLUSIONS

Post-paracentesis intravenous nutritional support combined with an oral nutritional protocol effectively improves muscle mass, while high-calorie, high-protein diets enhance handgrip strength. BCAA supplementation alone or with vitamin D has been shown to effectively enhance muscle strength and muscle mass. However, these findings should be interpreted cautiously due to low evidence certainty.

The Improvement of Physical Function and Caregiver Burden by a Multimodal Intervention: A Case Study of Combined Exercise Therapy, Nutritional Guidance, and Hydrogen Gas Inhalation Therapy

The objective of this exploratory case study was to examine the impact of a multifaceted intervention, which incorporated exercise therapy, nutritional guidance, and hydrogen gas inhalation, on the physical function and caregiver burden of an older female patient suspected of having sarcopenia. The methods employed included a three-month program of group exercise and individualized exercise sessions, three times per week, in addition to nutritional guidance and hydrogen gas inhalation therapy. The primary outcome measures included grip strength, walking speed, inflammatory/oxidative stress markers (c-reactive protein (CRP), interleukin-6 (IL-6), 8-hydroxy-2' -deoxyguanosine (8-OHdG)), and caregiver burden, which was assessed by the Family Caregiver Burden Scale (FCS). The results demonstrated that after a period of three months, there was an improvement in grip strength and walking speed. Concurrently, there was a decrease in CRP, IL-6, and 8-OHdG levels. The FCS score demonstrated a shift from the "severe" range to the "normal" range, suggesting a reduction in caregiver burden. The findings of this case study suggest that a multidisciplinary, multifaceted intervention combining exercise therapy, nutritional support, and hydrogen gas inhalation may be effective in enhancing physical function and reducing caregiver burden in older adults with suspected sarcopenia. However, further research is necessary to clarify the independent effects of hydrogen gas inhalation.

Vitamin D status and its determinants in German elite athletes

PURPOSE

This study investigated elite German athletes to (1) assess their serum 25(OH)D levels and the prevalence of insufficiency, (2) identify key factors influencing serum 25(OH)D levels, and (3) analyze the association between serum 25(OH)D levels and handgrip strength.

METHODS

In this cross-sectional study, a total of 474 athletes (231 female), aged 13-39 years (mean 19.3 years), from ten Olympic disciplines were included. Serum 25(OH)D levels were analyzed via liquid chromatography-mass spectrometry, and 17 single nucleotide polymorphisms (SNPs) related to vitamin D metabolism were determined using leukocyte DNA. Grip strength was measured unimanually using a hand-held dynamometer. Multiple linear regressions were used to analyze the influence of SNPs, age, sex, season (summer vs. winter), and discipline (indoor vs. outdoor) on 25(OH)D status. Linear regression analyzed the relationship between handgrip strength and serum 25(OH)D levels.

RESULTS

In total, 55.5% (n = 263) of athletes demonstrated insufficient serum 25(OH)D levels (< 30 ng/mL, < 75 nmol/L), with 16% (n = 76) showing levels below 20 ng/mL (50 nmol/L). After correction for multiple testing, significant influences on 25(OH)D levels were observed for the C allele of VDBP rs7041 (AC Genotype: β ^  = 7.46, p < .001; CC Genotype: β ^  = 6.23, p = .001). Age (all p < .01) and discipline (indoor vs. outdoor; all p < .05) also influenced serum 25(OH)D levels. Furthermore, serum 25(OH)D was positively associated with handgrip strength ( β ^ = 0.01, p < .001).

CONCLUSION

A high prevalence of insufficient 25(OH)D levels (< 30 ng/mL, < 75 nmol/L) was observed. We identified certain genetic variants as well as age and discipline as predictors of serum 25(OH)D levels. This knowledge may guide individualized diagnostic, nutritional, and supplementation strategies.

Diet and exercise in frailty and sarcopenia. Molecular aspects

Function declines throughout life although phenotypical manifestations in terms of frailty or disability are only seen in the later periods of our life. The causes underlying lifelong function decline are the aging process "per se", chronic diseases, and lifestyle factors. These three etiological causes result in the deterioration of several organs and systems which act synergistically to finally produce frailty and disability. Regardless of the causes, the skeletal muscle is the main organ affected by developing sarcopenia. In the first section of the manuscript, as an introduction, we review the quantitative and qualitative age-associated skeletal muscle changes leading to frailty and sarcopenia and their impact in the quality of life and independence in the elderly. The reversibility of frailty and sarcopenia are discussed in the second and third sections of the manuscript. The most effective intervention to delay and even reverse frailty is exercise training. We review the role of different training programs (resistance exercise, cardiorespiratory exercise, multicomponent exercise, and real-life interventions) not only as a preventive but also as a therapeutical strategy to promote healthy aging. We also devote a section in the text to the sexual dimorphic effects of exercise training interventions in aging. How to optimize the skeletal muscle anabolic response to exercise training with nutrition is also discussed in our manuscript. The concept of anabolic resistance and the evidence of the role of high-quality protein, essential amino acids, creatine, vitamin D, β-hydroxy-β-methylbutyrate, and Omega-3 fatty acids, is reviewed. In the last section of the manuscript, the main genetic interventions to promote robustness in preclinical models are discussed. We aim to highlight the molecular pathways that are involved in frailty and sarcopenia. The possibility to effectively target these signaling pathways in clinical practice to delay muscle aging is also discussed.

25-Hydroxyvitamin D Levels and Vitamin D3 Supplementation During Postacute Spinal Cord Injury Rehabilitation

Background

Insufficient 25-hydroxyvitamin D [25(OH)D] levels are associated with falls, fractures, and worse overall health outcomes. We evaluated 25(OH)D levels in individuals with spinal cord injury or disorder (SCI/D) during postacute rehabilitation who received vitamin D3 supplementation according to routine clinical practice. Associations with clinical outcomes were also assessed.

Methods

This prospective observational cohort study included individuals aged 18 to 85 years with newly acquired SCI/D admitted for inpatient rehabilitation to a specialized center. The following parameters were collected monthly from admission to discharge as part of the clinical routine: serum 25(OH)D, vitamin D3 supplementation, pressure injuries, bed rest, and falls. 25(OH)D levels were categorized as insufficient (≤75 nmol/L) or sufficient (>75 nmol/L). Descriptive statistics and group comparisons were performed.

Results

Eighty-seven patients (25 [29%] females, median age 53 [IQR 39-67] years) were included and followed for 186 (163-205) days. The proportion of patients with a sufficient 25(OH)D level increased from 8% (95% CI, 3-16) to 61% (95% CI, 50-71) (p < .001). Ninety-two percent of patients received vitamin D3 (1100 [1000-2000] IU/day). No differences in 25(OH)D levels or supplementation doses were found for the occurrence of pressure injuries, bed rest, or falls.

Conclusion

This is the first study to examine 25(OH)D levels and vitamin D3 supplementation during postacute SCI/D rehabilitation. Insufficient 25(OH)D levels were prevalent throughout rehabilitation. For some patients, the doses of vitamin D3 used in current clinical practice may be too low to achieve sufficient 25(OH)D levels. Regular monitoring of 25(OH)D levels and individualized supplementation strategies are warranted.

Effect of serum 25-hydroxyvitamin D level on quadriceps strength: a systematic review and meta-analysis

BACKGROUND

Vitamin D deficiency has been linked to poor muscle function, cartilage degeneration, and the development of knee osteoarthritis. However, the impact of serum 25-hydroxyvitamin D [25(OH)D] level on quadriceps muscle strength remains inconclusive, largely due to variations in study designs, differences in study populations, and the influence of confounding factors such as co-supplementation with other vitamins. The existing literature presents mixed findings, highlighting the need for a comprehensive evaluation of the available evidence.

PURPOSE

This systematic review and meta-analysis aim to summarise.

STUDY DESIGN

Systematic review; Level of evidence, 4.

METHODS

Searches were conducted using Medline (Ovid), Embase (Ovid), CINAHL (EBSCOhost), and SPORTDiscus (EBSCOhost), which aimed to summarise recent (published after 2000 and before March 1st, 2024) studies reporting the effects of serum 25(OH)D levels on quadriceps strength. Appraisal tool for Cross-Sectional Studies (AXIS) for cross-sectional studies and Quality in Prognosis Studies (QUIPS) for longitudinal studies. Results from the AXIS and QUIPS tools were used for GRADE quality assessment. The review was carried out using PRIMSA guidelines and registered in PROSPERO (ID: CRD42022313240).

RESULTS

Four hundred studies were screened and 28 studies with 5752 participants were included. 28 published studies (24 cross-sectional and 4 longitudinal) were identified. Key results supported the significant positive correlation between serum 25(OH)D levels and isokinetic quadriceps strength at 180°/s in elderly and athletic populations with a correlation coefficient of 0.245 (95%CI: 0.078-0.398, p = 0.004). However, no significant correlation was found with isometric quadriceps strength or isokinetic strength at 60°/s (r = 0.190, p = 0.085). There was only a weak negative correlation with MVC.

CONCLUSION

This review found a statistically significant positive correlation between serum 25(OH)D levels and isokinetic quadriceps strength. This has important clinical implications, especially in the elderly cohort, with higher 25(OH)D levels being associated with a reduced incidence of falls and fragility fractures.

A comparative study of hormonal contraceptive use and vitamin D levels at Gondar Town 2023

Vitamin D deficiency is an emerging public health problem globally, with devastating health consequences. Some studies suggest that exogenous sex hormones, found in hormonal contraceptives, may enhance vitamin D levels. However, the reasons for this association are not fully understood, as women using hormonal contraception may have different lifestyle habits affecting their vitamin D status. Therefore, this study seeks to explore the relationship between hormonal contraceptive use and vitamin D levels. A Facility based comparative cross-sectional study was conducted in Gondar town from February to April 2023, involving a total of 162 women using three types of hormonal contraceptives (Norplant, DMPA, and COC) and 162 age and BMI-matched non-users as controls in a 1:1 ratio. Participants were selected using systematic random sampling. A semi-structured questionnaire was used to collected data regarding the socio-demographic, economic, obstetric, lifestyle, and clinical information. 5 milliliters of blood samples were collected from each participant for Laboratory analysis of serum vitamin D, calcium, and alkaline phosphates using a Beckman Coulter chemistry analyzer. Independent t-tests, ANOVA with post hoc Bonferroni test was used to compare statistics between the two groups, and logistic regression models to identify factors associated with Vitamin D deficiency. The mean serum Vitamin D levels of Norplant, DMPA, and COC users were 24.08 (± 5.17), 24.83 (± 5.52), and 31.90 (± 6.94) respectively; whereas control group has mean Vitamin D level of 22.00 (± 7.97). On the current study the prevalence of Vitamin D deficiency (< 20 ng/ml) among hormonal contraceptive users was found to be 21.6% (35/162), whereas 48.14% (78/162) of non-user controls had vitamin D deficiency. The odds of having Vitamin D deficiency was higher among participants who attained higher education, who never eat fish and have never been used vitamin D Supplements. However, the use of combined oral contraceptives (COC) shown to reduce the odd of having vitamin D deficiency by 90%. Similarly, individuals with normal and hypercalcemia state shown to have lower odd of having Vitamin D deficiency. Users of combined oral contraceptives (COC) had significantly higher mean serum Vitamin D levels compared to users of Norplant and DMPA, as well as non-users. The prevalence of Vitamin D deficiency was lower among COC users compared to non-users, highlighting a potential protective effect of COC use against Vitamin D deficiency.

Update in exploring the connection and clinical implications between vitamin D and knee osteoarthritis

Knee osteoarthritis is a prevalent joint disorder characterized by cartilage degeneration, pain, and impaired physical function. Vitamin D might be implicated in the management of knee osteoarthritis through its effects on bone health, cartilage preservation, inflammation modulation, and muscle function. This literature review aims to synthesize the current state of literature to provide information about the correlation between vitamin D and knee osteoarthritis. Methods: We conducted a comprehensive literature search in databases such as PubMed, Web of Science, Scopus, and Google Scholar to identify studies published in the last ten years investigating the association between vitamin D and knee osteoarthritis. Vitamin D deficiency has been linked to cartilage degeneration and more severe symptomatology of knee osteoarthritis. The evidence supports an association between vitamin D levels and knee osteoarthritis, but with some studies showing mixed results, there is a need for further research.

Vitamin D and Sarcopenia in the Senior People: A Review of Mechanisms and Comprehensive Prevention and Treatment Strategies

This article reviews the mechanisms and prevention strategies associated with vitamin D and sarcopenia in older adults. As a geriatric syndrome, sarcopenia is defined by a notable decline in skeletal muscle mass and strength, which increases the risk of adverse health outcomes such as falls and fractures. Vitamin D, an essential fat-soluble vitamin, is pivotal in skeletal muscle health. It affects muscle function through various mechanisms, including regulating calcium and phosphorus metabolism, promoting muscle protein synthesis, and modulation of muscle cell proliferation and differentiation. A deficiency in vitamin D has been identified as a significant risk factor for the development of sarcopenia in older adults. Many studies have demonstrated that low serum vitamin D levels are significantly associated with an increased risk of sarcopenia. While there is inconsistency in the findings, most studies support the importance of vitamin D in maintaining skeletal muscle health. Vitamin D influences the onset and progression of sarcopenia through various pathways, including the promotion of muscle protein synthesis, the regulation of mitochondrial function, and the modulation of immune and inflammatory responses. Regarding the prevention and treatment of sarcopenia, a combination of nutritional, exercise, and pharmacological interventions is recommended. Further research should be conducted to elucidate the molecular mechanism of vitamin D in sarcopenia, to study genes related to sarcopenia, to perform large-scale clinical trials, to investigate special populations, and to examine the combined application of vitamin D with other nutrients or drugs. A comprehensive investigation of the interconnection between vitamin D and sarcopenia will furnish a novel scientific foundation and productive strategies for preventing and treating sarcopenia. This, in turn, will enhance the senior people's quality of life and health.

Dose optimization of pancreatic enzyme replacement therapy is essential to mitigate muscle loss in patients with advanced pancreatic cancer and exocrine pancreatic insufficiency

BACKGROUND & AIMS

Exocrine pancreatic insufficiency (EPI) contributes to malnutrition, marked by muscle loss during chemotherapy for advanced pancreatic cancer (aPC). Pancreatic enzyme replacement therapy (PERT) is recommended for patients with EPI; however, it's efficacy for attenuating muscle loss has not been demonstrated. We aimed to delineate the impact of PERT dose on muscle loss using a 7-year population-based cohort with aPC who were provided PERT at the discretion of their oncologist or dietitian according to clinical indications of EPI.

METHODS

All patients treated with chemotherapy for aPC from 2013 to 2019 in Alberta, Canada (population ∼4.3 million) were included if they had computed tomography (CT) scans both prior to and 12 ± 4 weeks after chemotherapy initiation. Change in muscle area (cm2) was measured at 3rd lumbar level on repeated CT scans. Muscle loss was defined by measurement error (loss >2.3 cm2). Clinical and pharmaceutical data were retrieved from provincial registries. For patients who were dispensed PERT -8 to +6 weeks from chemo start (PERT users), estimated dose consumed per day was calculated as: (total dose dispensed) / (days, first to last dispensation). PERT users were categorized as high dose or low dose users according to the median estimated dose consumed. Non-users were classified as No PERT. Association between PERT use and muscle loss was analyzed with multivariable logistic regression.

RESULTS

Among 210 patients, 81 (39%) were PERT users. Median estimated dose consumed per day of 75 000 USP lipase units defined the cutoff between low dose and high dose uses. There were no significant differences in baseline characteristics between high dose and low dose groups. Muscle loss was more prevalent among low dose compared to both high dose and No PERT groups (88% vs. 58% and 67%, p < 0.05). In the multivariable model predicting muscle loss, low dose PERT was independently associated with greater odds of muscle loss (OR 5.4, p = 0.004) vs. high dose, independent of tumour response, disease stage, and chemotherapy regimen.

CONCLUSION

In patients with clinical indications of EPI during chemotherapy for aPC, low doses of PERT were insufficient to prevent muscle loss. Patients with EPI consuming higher doses of PERT had similar odds of muscle maintenance to patients without clinical indications of EPI. Provider education for optimal PERT dosing in patients with EPI should be prioritized, and resources must be allocated to support dose titration.

Association of chronic liver disease with bone diseases and muscle weakness

The liver is a vital organ involved in nutrient metabolism, hormone regulation, immunity, cytokine production, and gut homeostasis. Impairment in liver function can result in malnutrition, chronic inflammation, decreased anabolic hormone levels, and dysbiosis. These conditions eventually cause an imbalance in osteoblast and osteoclast activities, resulting in bone loss. Osteoporosis is a frequent complication of chronic liver disease (CLD) that adversely affects quality of life and increases early mortality. Sarcopenia is another common complication of CLD characterized by progressive loss of skeletal muscle mass and function. Assessment criteria for sarcopenia specific to liver disease have been established, and sarcopenia has been reported to be associated with an increase in the risk of liver disease-related events and mortality in patients with CLD. Owing to their similar risk factors and underlying pathophysiological mechanisms, osteoporosis and sarcopenia often coexist (termed osteosarcopenia), progress in parallel, and further exacerbate the conditions mentioned above. Therefore, comprehensive management of these musculoskeletal disorders is imperative. This review summarizes the clinical implications and characteristics of osteoporosis, extending to sarcopenia and osteosarcopenia, in patients with CLD caused by different etiologies.

Emerging drugs for the treatment of sarcopenia in cirrhosis of the liver

INTRODUCTION

Malnutrition and sarcopenia are common and impact the prognosis in patients with liver cirrhosis. The etiology is multifactorial and includes periods of reduced caloric intake, increased catabolism and direct molecular mechanisms that inhibit muscle synthesis. Although these conditions are widely acknowledged, and there is a growing interest in their diagnosis, robust evidence regarding the treatment and reversibility of these conditions is still lacking.

AREAS COVERED

We have explored the current evidence on the pharmacological treatment of sarcopenia in patients with cirrhosis. Additionally, we have searched for drugs already in use and ongoing trials for other chronic diseases.

EXPERT OPINION

The current guidelines recommend the use of a protein-adequate diet and moderate physical activity for treating sarcopenia in patients with cirrhosis. Currently, robust evidence is derived only from the supplementation of Branched-Chain Amino Acids, capable of increasing muscle mass and function. There are many drugs targeting various pathways that contribute to sarcopenia. However, evidence is sporadic and insufficient to suggest their use in clinical practice.Novel drugs specifically designed to enhance muscle mass and function should be developed. Finally, gender significantly influences the type of muscle alteration and therapeutic mechanisms; therefore, future studies should be designed taking gender differences into consideration.

Navigating the Intersection: Sarcopenia and Sarcopenic Obesity in Inflammatory Bowel Disease

Inflammatory bowel diseases (IBDs) are intricate systemic conditions that can extend beyond the gastrointestinal tract through both direct and indirect mechanisms. Sarcopenia, characterized by a reduction in muscle mass and strength, often emerges as a consequence of the clinical course of IBDs. Indeed, sarcopenia exhibits a high prevalence in Crohn's disease (52%) and ulcerative colitis (37%). While computed tomography and magnetic resonance imaging remain gold-standard methods for assessing muscle mass, ultrasound is gaining traction as a reliable, cost-effective, and widely available diagnostic method. Muscle strength serves as a key indicator of muscle function, with grip strength test emerging nowadays as the most reliable assessment method. In IBDs, sarcopenia may arise from factors such as inflammation, malnutrition, and gut dysbiosis, leading to the formulation of the 'gut-muscle axis' hypothesis. This condition determines an increased need for surgery with poorer post-surgical outcomes and a reduced response to biological treatments. Sarcopenia and its consequences lead to reduced quality of life (QoL), in addition to the already impaired QoL. Of emerging concern is sarcopenic obesity in IBDs, a challenging condition whose pathogenesis and management are still poorly understood. Resistance exercise and nutritional interventions, particularly those aimed at augmenting protein intake, have demonstrated efficacy in addressing sarcopenia in IBDs. Furthermore, anti-TNF biological therapies showed interesting outcomes in managing this condition. This review seeks to furnish a comprehensive overview of sarcopenia in IBDs, elucidating diagnostic methodologies, pathophysiological mechanisms, and clinical implications and management. Attention will also be paid to sarcopenic obesity, exploring the pathophysiology and possible treatment modalities of this condition.

Physiology of Vitamin D-Focusing on Disease Prevention

Vitamin D is a crucial micronutrient, critical to human health, and influences many physiological processes. Oral and skin-derived vitamin D is hydroxylated to form calcifediol (25(OH)D) in the liver, then to 1,25(OH)2D (calcitriol) in the kidney. Alongside the parathyroid hormone, calcitriol regulates neuro-musculoskeletal activities by tightly controlling blood-ionized calcium concentrations through intestinal calcium absorption, renal tubular reabsorption, and skeletal mineralization. Beyond its classical roles, evidence underscores the impact of vitamin D on the prevention and reduction of the severity of diverse conditions such as cardiovascular and metabolic diseases, autoimmune disorders, infection, and cancer. Peripheral target cells, like immune cells, obtain vitamin D and 25(OH)D through concentration-dependent diffusion from the circulation. Calcitriol is synthesized intracellularly in these cells from these precursors, which is crucial for their protective physiological actions. Its deficiency exacerbates inflammation, oxidative stress, and increased susceptibility to metabolic disorders and infections; deficiency also causes premature deaths. Thus, maintaining optimal serum levels above 40 ng/mL is vital for health and disease prevention. However, achieving it requires several times more than the government's recommended vitamin D doses. Despite extensive published research, recommended daily intake and therapeutic serum 25(OH)D concentrations have lagged and are outdated, preventing people from benefiting. Evidence suggests that maintaining the 25(OH)D concentrations above 40 ng/mL with a range of 40-80 ng/mL in the population is optimal for disease prevention and reducing morbidities and mortality without adverse effects. The recommendation for individuals is to maintain serum 25(OH)D concentrations above 50 ng/mL (125 nmol/L) for optimal clinical outcomes. Insights from metabolomics, transcriptomics, and epigenetics offer promise for better clinical outcomes from vitamin D sufficiency. Given its broader positive impact on human health with minimal cost and little adverse effects, proactively integrating vitamin D assessment and supplementation into clinical practice promises significant benefits, including reduced healthcare costs. This review synthesized recent novel findings related to the physiology of vitamin D that have significant implications for disease prevention.

Adding Branched-Chain Amino Acids and Vitamin D to Whey Protein Is More Effective than Protein Alone in Preserving Fat Free Mass and Muscle Strength in the First Month after Sleeve Gastrectomy

OBJECTIVES

Sleeve gastrectomy (SG) is one of the most commonly performed weight loss (WL) bariatric procedures. The main goal of WL is reducing total body weight (TBW) and fat mass (FM). However, TBW loss is systematically accompanied by a decline in fat-free mass (FFM), predominantly in the first post-surgical month, despite protein supplementation. Branched-chain amino acids (BCAAs) and vitamin D seem to attenuate loss of FFM and, thus, reduce the decline in muscle strength (MS). However, data on the role of an integrated supplementation with whey protein plus BCAAs plus vitamin D (P+BCAAs+Vit.D) vs. protein alone on total weight loss (TWL), fat mass (FM), fat-free mass (FFM), and (MS) in the first month after SG are lacking. Therefore, the present study aims to evaluate the impact of P+BCAAs+Vit.D vs. protein alone supplementation on TWL, FM, FFM, and MS in the first month after SG.

MATERIALS AND METHODS

Before SG and at 1 month afterward, we prospectively measured and compared TBW, FM, FFM, and MS in 57 patients who received either a supplementation with P+BCAAs+Vit.D (n = 31) or protein alone (n = 26). The impact of P+BCAAs+Vit.D and protein alone supplementation on clinical status was also evaluated.

RESULTS

Despite non-significant variation in TBW, FM decreased more significantly (18.5% vs. 13.2%, p = 0.023) with the P+BCAA+Vit.D supplementation compared to protein alone. Furthermore, the P+BCAA+Vit.D group showed a significantly lower decrease in FFM (4.1% vs. 11.4%, p < 0.001) and MS (3.8% vs. 18.5%, p < 0.001) compared to the protein alone group. No significant alterations in clinical status were seen in either group.

CONCLUSION

P+BCAA+Vit.D supplementation is more effective than protein alone in determining FM loss and is associated with a lower decrease in FFM and MS, without interfering with clinical status in patients 1 month after SG.

Low vitamin D levels accelerates muscle mass loss in patients with chronic liver disease

Sarcopenia frequently and progressively occurs in patients with chronic liver disease. This study aimed to clarify the relationship between vitamin D levels and muscle mass loss. A total of 166 patients with chronic liver disease were enrolled in this study. Skeletal muscle mass index (SMI) was measured by bioelectrical impedance analysis at baseline and after 1 year. The rate of change in SMI from baseline after 1 year was calculated: ΔSMI (%) = [(1-year SMI - baseline SMI) / baseline SMI] × 100. Muscle mass loss was defined as ΔSMI ≤ -2%. The median 25-hydroxyvitamin D was 15.2 (11.2-19.3) ng/mL. The median SMI were 6.8 (5.9-7.8) kg/m2 at baseline and 6.7 (5.9-7.6) kg/m2 after 1 year. The median ΔSMI was -1.23% (-2.21% to 1.61%). Multivariate analysis identified low 25-hydroxyvitamin D as an independent factor associated with muscle mass loss. The optimal cut-off value of 25-hydroxyvitamin D to predict muscle mass loss was 12.7 ng/mL. Muscle mass loss was found in 56.4% v.s. 18.0% of patients with 25-hydroxyvitamin D < 12.7 vs. ≥ 12.7 ng/mL, respectively (p = 9.01 × 10-7); with the highest incidence in patients with non-alcoholic fatty liver disease (NAFLD). Specifically, patients with NAFLD and 25-hydroxyvitamin D < 12.7 ng/mL had a significantly higher incidence of muscle mass loss than those with ≥ 12.7 ng/mL (p = 1.23 × 10-3). Low vitamin D levels are associated with muscle mass loss after 1 year in patients with chronic liver disease, especially NAFLD.

The effects of 12 weeks resistance training and vitamin D administration on neuromuscular joint, muscle strength and power in postmenopausal women

BACKGROUND

This study aimed to examine the effects of 12 weeks of resistance training (RT) and vitamin D (VitD) supplementation on muscle strength and C-terminal agrin fragment (CAF) and Neurotrophin-3 (NT-3) concentrations as potential biomarkers in postmenopausal women.

METHODS

This was a randomized double-blind placebo-controlled study. Forty-four healthy postmenopausal women (55.84 ± 4.70 years and 29.61 ± 4.26 kg/m2) were randomly assigned into four groups: (1) Resistance training + placebo (RT + PLA), (2) Vitamin D supplementation (VitD), (3) Resistance training + vitamin D (RT + VitD), and (4) Placebo (PLA). VitD was supplemented as an oral capsule containing 50000 IU of cholecalciferol every two weeks. RT involved leg press, chest press, leg extension, leg curl, and shoulder press exercises, performed with 3-4 sets at 70-85 % of 1RM, three times a week.

RESULTS

Circulating levels of CAF and NT-3 did not significantly change following the intervention period in the study groups (p > 0.05). There were significant increases in upper and lower body muscle strength and power for RT + VitD and RT + PLA ( < 0.05), but not for VitD or PLA (p > 0.05). The muscle function gains for RT + VitD and RT + PLA were higher than those for VitD and PLA but did not differ between them.

CONCLUSION

12-week of RT interventions resulted in significant increases in muscle strength and power in postmenopausal women. However, VitD supplementation did not result in any additional benefits. The positive changes in muscle function promoted by RT do not seem to be associated with changes in the neuromuscular joint via the CAF or NT-3 as potential biomarkers.

The prevalence and factors associated with sarcopenia in Thai older adults: A systematic review and meta-analysis

Objective

This systematic review and meta-analysis aimed to assess the prevalence and identify factors associated with sarcopenia in older Thais.

Methods

Research studies were searched in online databases, including PubMed, Embase, Scopus, and Thai-Journal Citation Index. The articles included in this review were limited to being published between January 1, 2013 and January 31, 2023 and observational study designs. The research quality was evaluated using the Joanna Briggs Institute (JBI) critical appraisal tool for prevalence studies. A meta-analysis was performed using the JBI SUMARI software. The review protocol has been registered on PROSPERO with the assigned ID CRD42023420514.

Results

A total of 265 research articles were initially identified, out of which 17 articles were included in this study, including a total of 4,668 participants aged 60 years and over, consisting of 1,380 (29.6%) men and 3,288 (70.4%) women. The overall prevalence of sarcopenia in Thai older adults was 20.7% (95% CI 14.4%-27.8%). Subgroup analysis of the sarcopenia prevalence based on the study areas revealed that the prevalence was 33.4% (95% CI 28.7%-38.3%) in hospitalized individuals, 23.2% (95% CI 12.5%-35.9%) in outpatient clinic settings, and 17.3% (95% CI 9.4%-26.8%) in community-living older adults. Advanced age (OR = 4.60, 95% CI 3.07-6.91), being male (OR = 2.30, 95% CI 1.37-3.85), low body mass index (BMI) (OR = 8.95, 95% CI 6.05-13.25), and malnutrition (OR = 2.78, 95% CI 2.09-3.70) are strong predictors of sarcopenia in older adults in Thailand.

Conclusions

This systematic review represents the first assessment of the overall prevalence and factors associated with sarcopenia in Thai older adults, indicating its significant concern within this population. These findings are of importance for public health management aimed at preventing and managing sarcopenia in the country.

Nutritional strategies to optimise musculoskeletal health for fall and fracture prevention: Looking beyond calcium, vitamin D and protein

Falls and osteoporotic fractures are a major public health problem, particularly among older adults. A third of individuals aged 65 years and over fall at least once each year, with up to 20 % of these resulting in serious injury, including fracture. In conjunction with regular exercise, the importance of diet for musculoskeletal health has largely focused upon calcium, vitamin D, and protein, particularly in the context of preventing falls and fractures. Whilst there is evidence for the benefits of these nutrients for musculoskeletal health, other aspects of the diet remain largely underexplored. For example, vegetables are rich sources of macro- and micronutrients that are essential for muscle function and bone health, which are key factors in the prevention of falls and fractures. Recent work has highlighted the importance of nutrients such as vegetable-derived nitrate and vitamin K1 in optimising muscle strength, physical function, and bone quality. In the context of dietary patterns, vegan/plant-based diets have recently gained popularity due to perceived health benefits, animal welfare, or to tackle climate change. The elimination and/or substitution of animal-based products for plant foods (without careful planning and/or expert dietary guidance) could, however, have long-term negative musculoskeletal consequences; a trend uncovered by recent evidence. Within the overarching theme of nutrition for fall and fracture prevention in older populations, the aim of this review is to (i) summarise the current evidence for calcium, vitamin D and protein; (ii) describe the importance of vegetables and selected nutrients, such as nitrate and vitamin K1, for muscle function and bone structural integrity; and (iii) highlight current evidence around different dietary patterns (e.g., plant-based, diet quality, data driven approaches) and their impact on musculoskeletal health.

TGF-β1 stimulation and VDR-dependent activation modulate calcitriol action on skeletal muscle fibroblasts and Smad signalling-associated fibrogenesis

Fibroblasts play a pivotal role in fibrogenesis after skeletal muscle injury. Excess fibrous formation can disrupt contractile functions and delay functional recovery. Although vitamin D receptor (VDR) is expressed explicitly in regenerating muscle compared with uninjured muscle, how calcitriol [1α,25(OH)2D3] directly regulates skeletal muscle primary fibroblast proliferation, the transition to myofibroblasts, and Smad signalling-associated fibrogenesis is currently unknown. Herein, the effects of calcitriol on cultured skeletal muscle primary fibroblasts of male C57BL/6 mice (aged 1 month old) were investigated. The percentage of BrdU+ nuclei in primary fibroblasts was significantly decreased after calcitriol treatment; however, the antiproliferative effect of calcitriol was diminished after TGF-β1 stimulation to induce fibroblast to myofibroblast transition. This suppressive effect was associated with significantly decreased VDR expression in TGF-β1-treated cells. In addition, Vdr siRNA transfection abolished the effects of calcitriol on the suppression of α-SMA expression and Smad2/3 signalling in myofibroblasts, supporting that its antifibrogenic effect requires VDR activation. Compared with calcitriol, the antifibrotic agent suramin could inhibit fibroblast/myofibroblast proliferation and suppress the expression of TCF-4, which regulates fibrogenic determination. Collectively, these findings suggest that profibrotic stimulation and VDR-dependent activation could modulate the effects of calcitriol on skeletal muscle fibroblast proliferation and fibrogenesis processes. Therefore, TGF-β1 and VDR expression levels are crucial determinants for the antifibrogenic effect of calcitriol on skeletal muscle after injury.

Vitamin D Supplementation Influences Ultramarathon-Induced Changes in Serum Amino Acid Levels, Tryptophan/Branched-Chain Amino Acid Ratio, and Arginine/Asymmetric Dimethylarginine Ratio

Exercise affects serum levels of amino acids and their metabolites, with important metabolic consequences. Since vitamin D impacts skeletal muscle protein degradation, we hypothesised that it would also impact exercise-induced changes in serum amino acid levels and the serum levels of arginine metabolites, influencing the body's ability to synthesise NO. Accordingly, we analysed the effect of a single high-dose vitamin D supplementation on the serum levels of various amino acids in ultramarathon runners. Thirty-five male amateur runners were assigned to the supplemented group, administered 150,000 IU vitamin D in vegetable oil 24 h before the run (n = 16), or the control (placebo) group (n = 19). Blood was sampled 24 h before, immediately after, and 24 h after the run. Changes in the serum levels of some amino acids were distinct in the two groups. The asymmetric dimethyl arginine levels were significantly decreased immediately after the run and increased 24 h later and were not affected by the supplementation. The symmetric dimethyl arginine levels were increased after the run in both groups but were lower in the supplemented group than in the placebo group 24 h after the run. The dimethylamine levels increased significantly in the supplemented group as compared to the placebo group. In conclusion, vitamin D impacts exercise-induced changes in serum amino acids and methylated arginine metabolites.

Association of Serum Vitamin D Level with Temporomandibular Disorder Incidence: A Retrospective, Multi-Center Cohort Study Using Six Hospital Databases

The relationship between serum vitamin D levels and temporomandibular disorders (TMDs) remains unclear. Therefore, this study aimed to investigate the association between serum 25-hydroxyvitamin D (25[OH]D) levels and TMD incidence using large-scale health data. Clinical data from the electronic health records of six secondary or tertiary hospitals in Korea were used to evaluate the relationship between serum 25(OH)D levels and TMD incidence. The data were converted to the Observational Medical Outcomes Partnership Common Data Model. A cohort study was designed using the Cox proportional hazards model to examine the hazard ratio (HR) of TMD development after propensity score matching (PSM). An aggregate meta-analysis of the HR was subsequently performed. After 1:4 PSM, a target group with deficient 25(OH)D levels (<20 ng/mL) (N = 34,560) and comparator group with non-deficient 25(OH)D levels (≥20 ng/mL) (N = 47,359) were pooled from six hospital databases. HR meta-analysis demonstrated a significant association between deficient 25(OH)D levels and TMD incidence (pooled HR: 1.50; 95% confidence interval: 1.07-2.12). In conclusion, deficient 25(OH)D levels were found to be associated with an increased TMD risk. Therefore, vitamin D deficiency is a potential risk factor for TMD development.

Prevalence and risk factors of osteosarcopenia: a systematic review and meta-analysis

BACKGROUND

Osteosarcopenia is a syndrome with a concomitant presence of both sarcopenia and osteopenia/osteoporosis. It increases the risk of frailty, falls, fractures, hospitalization, and death. Not only does it burden the lives of older adults, but it also increases the economic burden on health systems around the world. This study aimed to review the prevalence and risk factors of osteosarcopenia to generate important references for clinical work in this area.

METHODS

Pubmed, Embase, Cochrane Library, Web of Science, CNKI, Wanfang, CBM, and VIP databases were searched from inception until April 24th, 2022. The quality of studies included in the review was evaluated using the NOS and AHRQ Scale. Pooled effects of the prevalence and associated factors were calculated using random or fixed effects models. Egger's test, Begg's test, and funnel plots were used to test the publication bias. Sensitivity analysis and subgroup analysis were conducted to identify the sources of heterogeneity. Statistical analysis was performed using Stata 14.0 and Review Manager 5.4.

RESULTS

A total of 31 studies involving 15,062 patients were included in this meta-analysis. The prevalence of osteosarcopenia ranged from 1.5 to 65.7%, with an overall prevalence of 21% (95% CI: 0.16-0.26). The risk factors for osteosarcopenia were female (OR 5.10, 95% CI: 2.37-10.98), older age (OR 1.12, 95% CI: 1.03-1.21), and fracture (OR 2.92, 95% CI: 1.62-5.25).

CONCLUSION

The prevalence of osteosarcopenia was high. Females, advanced age, and history of fracture were independently associated with osteosarcopenia. It is necessary to adopt integrated multidisciplinary management.

Vitamin D Supplementation and Muscle Power, Strength and Physical Performance in Older Adults: A Randomized Controlled Trial

BACKGROUND

Low 25-hydroxyvitamin D (25[OH]D) concentrations (<30 ng/mL [<50 nmol/L]) have been associated with muscle weakness and impaired physical performance in observational studies. However, the effect of vitamin D supplementation on changes in muscle strength and physical performance in randomized controlled trials has been mixed.

OBJECTIVES

To determine the effect of daily vitamin D supplementation on leg power, strength, and physical performance in low-functioning older adults with 25(OH)D concentrations of 18 to <30 ng/mL.

METHODS

In this double-blind, randomized controlled trial, 136 low-functioning [Short Physical Performance Battery (SPPB) scores ≤10] adults aged 65-89 y with 25(OH)D concentrations of 18 to <30 ng/mL were randomly assigned to 2000 IU/d vitamin D3 or placebo for 12 mo. Lower-extremity leg power (primary outcome), leg and grip strength, SPPB, timed up and go (TUG), postural sway, and gait velocity and spatiotemporal parameters (secondary outcomes) were assessed at baseline, 4 and 12 mo. A subset (n = 37) also underwent a muscle biopsy at baseline and 4 mo and muscle fiber composition and contractile properties were assessed.

RESULTS

Participants' mean ± SD age and SPPB scores at baseline were 73.4 ± 6.3 y and 7.8 ± 1.8, respectively. Mean ± SD 25(OH)D concentrations at baseline and 12 mo were 19.4 ± 4.2 ng/mL and 28.6 ± 6.7 ng/mL in the vitamin D group and 19.9 ± 4.9 ng/mL and 20.2 ± 5.0 ng/mL in the placebo group for a mean ± SE difference of 9.1 ± 1.1 ng/mL (P < 0.0001). However, there were no differences in change in leg power, leg or grip strength, SPPB score, TUG, postural sway, or gait velocity and spatiotemporal parameters by intervention group over 12 mo or muscle fiber composition and contractile properties over 4 mo.

CONCLUSIONS

In low-functioning older adults with 25(OH)D concentrations of 18 to <30 ng/mL, randomization to 2000 IU/d vitamin D3 did not result in improvements in leg power, strength, or physical performance or muscle fiber composition and contractile properties. This trial was registered at clinicaltrials.gov as NCT02015611.

25-hydroxyvitamin D level is associated with greater grip strength across adult life span: a population-based cohort study

OBJECTIVE

Maintaining muscle function throughout life is critical for healthy ageing. Although in vitro studies consistently indicate beneficial effects of 25-hydroxyvitamin D (25-OHD) on muscle function, findings from population-based studies remain inconclusive. We therefore aimed to examine the association between 25-OHD concentration and handgrip strength across a wide age range and assess potential modifying effects of age, sex and season.

METHODS

We analysed cross-sectional baseline data of 2576 eligible participants out of the first 3000 participants (recruited from March 2016 to March 2019) of the Rhineland Study, a community-based cohort study in Bonn, Germany. Multivariate linear regression models were used to assess the relation between 25-OHD levels and grip strength while adjusting for age, sex, education, smoking, season, body mass index, physical activity levels, osteoporosis and vitamin D supplementation.

RESULTS

Compared to participants with deficient 25-OHD levels (<30 nmol/L), grip strength was higher in those with inadequate (30 to <50 nmol/L) and adequate (≥50 to ≤125 nmol/L) levels (ßinadequate = 1.222, 95% CI: 0.377; 2.067, P = 0.005; ßadequate = 1.228, 95% CI: 0.437; 2.019, P = 0.002). Modelling on a continuous scale revealed grip strength to increase with higher 25-OHD levels up to ~100 nmol/L, after which the direction reversed (ßlinear = 0.505, 95% CI: 0.179; 0.830, P = 0.002; ßquadratic = -0.153, 95% CI: -0.269; -0.038, P = 0.009). Older adults showed weaker effects of 25-OHD levels on grip strength than younger adults (ß25OHDxAge = -0.309, 95% CI: -0.594; -0.024, P = 0.033).

CONCLUSIONS

Our findings highlight the importance of sufficient 25-OHD levels for optimal muscle function across the adult life span. However, vitamin D supplementation should be closely monitored to avoid detrimental effects.

Effect of Vitamin D analog supplementation on levator ani strength and plasma Vitamin D receptor expression in uterine prolapse patients

Uterine prolapse is a pathological condition that can negatively impact women's quality of life. It is caused by weakening of the pelvic floor muscles. Function of levator ani muscle and other striated muscles is thought to be influenced by Vitamin D levels. Vitamin D exerts its biological effects by adhering to Vitamin D receptors (VDRs) present in striated muscles. We aim to analyze the effect of Vitamin D analog supplementation on levator ani muscle strength in uterine prolapse patients. This was a quasi-experimental study with a pre-post design on 24 postmenopausal women diagnosed with grade III and IV uterine prolapse. Vitamin D levels, VDR, levator ani muscle, and hand grip muscle strength were measured before and after three months of Vitamin D analog supplementation. We found that Vitamin D level, VDR serum level, levator ani muscle strength, and hand grip muscle strength all significantly increase (p < 0.001) following Vitamin D analog supplementation. The correlation coefficient between levator ani muscle and handgrip muscle strength was 0.616 and with p value of 0.001. To conclude, Vitamin D analog supplementation can significantly increase levator ani muscle strength in uterine prolapse patients. We propose that determining Vitamin D level in postmenopausal women and replenishing its deficiency with Vitamin D analog supplementation might aid in preventing POP progression.

Vitamin D as a Shield against Aging

Aging can be seen as a physiological progression of biomolecular damage and the accumulation of defective cellular components, which trigger and amplify the process, toward whole-body function weakening. Senescence initiates at the cellular level and consists in an inability to maintain homeostasis, characterized by the overexpression/aberrant expression of inflammatory/immune/stress responses. Aging is associated with significant modifications in immune system cells, toward a decline in immunosurveillance, which, in turn, leads to chronic elevation of inflammation/oxidative stress, increasing the risk of (co)morbidities. Albeit aging is a natural and unavoidable process, it can be regulated by some factors, like lifestyle and diet. Nutrition, indeed, tackles the mechanisms underlying molecular/cellular aging. Many micronutrients, i.e., vitamins and elements, can impact cell function. This review focuses on the role exerted by vitamin D in geroprotection, based on its ability to shape cellular/intracellular processes and drive the immune response toward immune protection against infections and age-related diseases. To this aim, the main biomolecular paths underlying immunosenescence and inflammaging are identified as biotargets of vitamin D. Topics such as heart and skeletal muscle cell function/dysfunction, depending on vitamin D status, are addressed, with comments on hypovitaminosis D correction by food and supplementation. Albeit research has progressed, still limitations exist in translating knowledge into clinical practice, making it necessary to focus attention on the role of vitamin D in aging, especially considering the growing number of older individuals.

Effects of maternal and offspring treatment with two dietary sources of vitamin D on the mineral homeostasis, bone metabolism and locomotion of offspring fed protein- and phosphorus-reduced diets

The present study aims to compare the effects of maternal and offspring treatment with 25-hydroxycholecalciferol (25-OHD₃) and vitamin D₃ on vitamin D status, mineral homoeostasis, bone metabolism and locomotion in the offspring. Either vitamin D₃ (50 μg/kg diet) or 25-OHD₃ (50 μg/kg diet) was supplemented to the gestation and lactation diets of 49 multiparous sows and/or to the diets of their growing offspring. Treatment of the sows did not affect plasma concentrations of 25-OHD₃ of the offspring. Pigs fed 25-OHD₃ had higher plasma concentrations of 25-OHD₃ than pigs that received vitamin D₃ during rearing and fattening. However, neither plasma concentrations of calcium, phosphate and bone markers during the observation period nor bone ash and bone mineral density at slaughter were clearly affected by the treatment. Maternal and offspring treatment with 25-OHD₃ instead of vitamin D₃ resulted in a slight reduction in the prevalence of leg swelling. In addition, more pigs walked with even steps and normal stride length. Further studies are needed to test whether the slight effects observed in the present experiment are reproducible and of relevance for animal health and welfare. In that case, the underlying mechanisms should be revealed in order to take advantage of potentially beneficial influences especially under certain feeding regimes.

Advances in the molecular pathogenesis and cell therapy of stress urinary incontinence

Stress urinary incontinence (SUI) is very common in women. It affects patients' mental and physical health, and imposed huge socioeconomic pressure. The therapeutic effect of conservative treatment is limited, and depends heavily on patient persistence and compliance. Surgical treatment often brings procedure-related adverse complications and higher costs for patients. Therefore, it is necessary to better understand the potential molecular mechanisms underlying stress urinary incontinence and develop new treatment methods. Although some progress has been made in the basic research in recent years, the specific molecular pathogenic mechanisms of SUI are still unclear. Here, we reviewed the published studies on the molecular mechanisms associated with nerves, urethral muscles, periurethral connective tissue and hormones in the pathogenesis of SUI. In addition, we provide an update on the recent progresses in research on the use of cell therapy for treating SUI, including research on stem cells therapy, exosome differentiation and gene regulation.

Is vitamin D replacement effective in the treatment of postpartum urinary incontinence?

INTRODUCTION AND HYPOTHESIS

The main objective of this study was to compare the effectiveness of pelvic floor muscle training, and vitamin D replacement in the treatment of urinary incontinence in the postpartum period of pregnant women with vitamin D deficiency.

METHODS

The study was planned as an ancillary study of a study on the determination of the relationship between vitamin D deficiency and urinary incontinence in third-trimester pregnant women. Total 61 women who defined urinary incontinence at postpartum 8th week were included in the study. The participants were divided into two groups: the vitamin D replacement group and the pelvic floor muscle training (PFMT) group. Participants in both groups received appropriate treatment for 12 weeks. İnitial evaluations of which Pelvic Organ Prolapse-Quantification stage, International Consultation on Incontinence Modular Questionnaire on Female Lower Urinary Tract Symptoms (ICIQ-FLUTS) query, and pelvic floor muscle strength were repeated after 12 weeks of treatment for each patient.

RESULTS

In the vitamin D replacement group, there was a significant increase in Oxford scores measured after treatment compared with pre-treatment and a significant decrease in ICIQ-FLUTS scores. In the comparison of the groups, it was determined that the changes in the Oxford and ICIQ-FLUTS scores of the vitamin D group after treatment were significantly higher than those of the PFMT group. In this pilot study, it was determined that the effectiveness of vitamin D replacement in the treatment of pelvic floor dysfunction in pregnant women with hypovitaminosis D was significantly higher than PFMT.

CONCLUSION

Vitamin D replacement may be useful in the treatment of urinary incontinence in pregnant women with hypovitaminosis D.

Vitamin D: sources, physiological role, biokinetics, deficiency, therapeutic use, toxicity, and overview of analytical methods for detection of vitamin D and its metabolites

Vitamin D has a well-known role in the calcium homeostasis associated with the maintenance of healthy bones. It increases the efficiency of the intestinal absorption of dietary calcium, reduces calcium losses in urine, and mobilizes calcium stored in the skeleton. However, vitamin D receptors are present ubiquitously in the human body and indeed, vitamin D has a plethora of non-calcemic functions. In contrast to most vitamins, sufficient vitamin D can be synthesized in human skin. However, its production can be markedly decreased due to factors such as clothing, sunscreens, intentional avoidance of the direct sunlight, or the high latitude of the residence. Indeed, more than one billion people worldwide are vitamin D deficient, and the deficiency is frequently undiagnosed. The chronic deficiency is not only associated with rickets/osteomalacia/osteoporosis but it is also linked to a higher risk of hypertension, type 1 diabetes, multiple sclerosis, or cancer. Supplementation of vitamin D may be hence beneficial, but the intake of vitamin D should be under the supervision of health professionals because overdosing leads to intoxication with severe health consequences. For monitoring vitamin D, several analytical methods are employed, and their advantages and disadvantages are discussed in detail in this review.

Association of serum 25-hydroxy vitamin D with gait speed and handgrip strength in patients on hemodialysis

BACKGROUND

Muscle dysfunction is prevalent in dialysis patients. Gait speed and handgrip strength are simple and reliable methods of assessing muscle function. Numerous observational studies have linked 25-hydroxy vitamin D[25(OH)D] status with gait speed and handgrip strength in populations without kidney diseases. This study aimed to evaluate the potential associations of 25(OH)D status with gait speed and handgrip strength in patients on hemodialysis.

METHODS

In this observational cross-sectional study, demographic data, biological data, and dialysis parameters were collected. Gait speed and handgrip strength were measured. Multiple linear regression and logistic regression analysis were used to investigate the relationship of 25(OH)D status with gait speed and handgrip strength after adjusting for potential confounders.

RESULTS

Overall, a total of 118 participants undergoing hemodialysis were included. Seventy-one (60.2%) participants were male. The median 25(OH)D status in participants was 11.58 (interquartile range: 8.51 to 15.41) ng/ml. When controlling for age, gender, dialysis vintage, and other confounders with a p-value < 0.15 in univariate analyses, 25(OH)D was significantly positively associated with gait speed (β = 0.16, 95% CI 0.05 to 0.28, p = 0.006) and handgrip strength (β = 3.83, 95% CI 1.09 to 6.56, p = 0.007).

CONCLUSION

Our study showed that 25(OH)D status seemed to be associated with gait speed and handgrip strength in patients on hemodialysis. However, these results were not robust. The relationships between 25(OH)D status and gait speed and handgrip should be further explored.

The Combined Relationship of Vitamin D and Weight-Bearing Sports Participation on Areal Bone Density and Geometry Among Adolescents: ABCD - Growth Study

Osteoporosis is a public health problem, which negatively impacts society and national health services worldwide. Altered mineralization of the skeleton can be caused by persistent vitamin D deficiency. However, the combined impact of both on bone health is still under investigation. In fact, although there is compelling evidence in the literature about the positive effect of weight-bearing sports participation on bone mineral density, its impact on bone geometry gains more attention in pediatric population. The sports modalities that we evaluated were artistic gymnastics and track and field. Nonsports group was composed of 43 adolescents. Bone density was assessed using dual-energy X-ray absorptiometry. Vitamin D concentration was assessed by blood analysis. In the crude comparison of bone outcomes, the sport group presented higher aBMD only in the trochanter (p-value = 0.040). Considering the combination of the engagement in sports and vitamin D, adolescents in the sports group presented significantly higher values of aBMD in lower limbs, whole body, trochanter, shaft, and femur whole body (p-value = 0.024, 0.035, 0.001, 0.019 and 0.003 respectly). In contrast, only the sport group with high vitamin D presented a higher CSA (p-value = 0.015) and femur neck aBMD compared to the non-sport/low vitamin D group. Only adolescents with a combination of sports participation and higher serum concentrations of vitamin D presented better bone geometry, denoting the relevance of the combination of both factors to bone health.

Vitamin D, exercise, and immune health in athletes: A narrative review

Vitamin D exerts important extra-skeletal effects, exhibiting an exquisite immune regulatory ability, affecting both innate and adaptive immune responses through the modulation of immunocyte function and signaling. Remarkably, the immune function of working skeletal muscle, which is fully recognized to behave as a secretory organ with immune capacity, is under the tight control of vitamin D as well. Vitamin D status, meaning hormone sufficiency or insufficiency, can push toward strengthening/stabilization or decline of immune surveillance, with important consequences for health. This aspect is particularly relevant when considering the athletic population: while exercising is, nowadays, the recommended approach to maintain health and counteract inflammatory processes, “too much” exercise, often experienced by athletes, can increase inflammation, decrease immune surveillance, and expose them to a higher risk of diseases. When overexercise intersects with hypovitaminosis D, the overall effects on the immune system might converge into immune depression and higher vulnerability to diseases. This paper aims to provide an overview of how vitamin D shapes human immune responses, acting on the immune system and skeletal muscle cells; some aspects of exercise-related immune modifications are addressed, focusing on athletes. The crossroad where vitamin D and exercise meet can profile whole-body immune response and health.

The Use of Dietary Supplements and Amino Acid Restriction Interventions to Reduce Frailty in Pre-Clinical Models

Frailty is a state of accelerated aging that increases susceptibility to adverse health outcomes. Due to its high societal and personal costs, there is growing interest in discovering beneficial interventions to attenuate frailty. Many of these interventions involve the use of lifestyle modifications such as dietary supplements. Testing these interventions in pre-clinical models can facilitate our understanding of their impact on underlying mechanisms of frailty. We conducted a narrative review of studies that investigated the impact of dietary modifications on measures of frailty or overall health in rodent models. These interventions include vitamin supplements, dietary supplements, or amino acid restriction diets. We found that vitamins, amino acid restriction diets, and dietary supplements can have beneficial effects on frailty and other measures of overall health in rodent models. Mechanistic studies show that these effects are mediated by modifying one or more mechanisms underlying frailty, in particular effects on chronic inflammation. However, many interventions do not measure frailty directly and most do not investigate effects in both sexes, which limits their applicability. Examining dietary interventions in animal models allows for detailed investigation of underlying mechanisms involved in their beneficial effects. This may lead to more successful, translatable interventions to attenuate frailty.

The Role of Lifestyle Intervention, in Addition to Drugs, for Diabetic Kidney Disease with Sarcopenic Obesity

Diabetic kidney disease is the leading cause of end-stage renal disease in developing and developed countries. The growing prevalence and clinical challenges of sarcopenic obesity have been associated with the frailty and disability of diabetic kidney disease. It has been reported that insulin resistance, chronic inflammation, enhanced oxidative stress and lipotoxicity contribute to the pathophysiology of muscle loss and visceral fat accumulation. Sarcopenic obesity, which is diagnosed with dual-energy X-ray absorptiometry, is associated with worse outcomes in kidney disease. Growing evidence indicates that adherence to healthy lifestyles, including low protein diet, proper carbohydrate control, vitamin D supplement, and regular physical training, has been shown to improve clinical prognosis. Based on the higher risk of sarcopenic-obesity-related renal function decline, it has led to the exploration and investigation of the pathophysiology, clinical aspects, and novel approach of these controversial issues in daily practice.

A relationship among the blood serum levels of interleukin-6, albumin, and 25-hydroxyvitamin D and frailty in elderly patients with chronic coronary syndrome

Background

With the aggravation of the aging of the world population, frailty has become one of the common complications in elderly people. Its diagnosis is not objective, the pathogenesis is not clear, and interventions are not sound, thus intensifying the problem. Furthermore, frailty is closely associated with the occurrence and poor prognosis of coronary atherosclerotic heart disease. Moreover, few studies report on the prevalence of frailty in elderly patients with the chronic coronary syndrome (CCS).

Objective

We aimed to investigate the prevalence of frailty in elderly patients with CCS. We analyzed the correlation between the blood serum levels of interleukin-6 (IL-6), albumin (Alb), and 25-hydroxyvitamin D (25(OH)D) with frailty in elderly patients with CCS. We have also provided recommendations for helping the objective diagnosis as well as proposed new intervention methods in the future.

Methods

Two hundred eight-eight inpatients (≥60 years) with the chronic coronary syndrome were recruited at the Department of Geriatrics, the First People's Hospital of Yunnan Province, China. General information and laboratory examination data were collected. The comprehensive geriatric assessment was conducted via an internet-based platform of the Comprehensive Geriatric Assessment (inpatient version) developed by us, among which frailty was assessed by the Chinese version of Fried Frailty Phenotype, a component of the assessment scale.

Results

Among the total number of old patients with CCS, 87 (30.2%) had no frailty, 93 (32.3%) had early frailty, and 108 (37.5%) had frailty. According to the multivariate logistic regression analysis, after adjusting for confounding factors, IL-6 (OR = 1.066, 95% CI 1.012-1.127), Alb (OR = 0.740, 95% CI 0.560-0.978), and 25(OH)D (OR = 0.798, 95% CI 0.670-0.949) were independently associated with frailty in the three groups of models.

Conclusion

IL-6 proved to be a risk factor for frailty in elderly patients with CCS, while Alb and 25(OH)D were protective factors, which make the potential targets for predicting and intervening frailty in elderly patients with CCS.

Effects of vitamin D supplementation and aerobic exercises on balance and physical performance in children with Down syndrome

Background/Aims

Children with Down syndrome are prone to vitamin D deficiency. Vitamin D supplements are commonly used to treat and prevent vitamin D deficiencies. There is growing evidence that support the role of vitamin D improving muscles and central nervous system function. The aim of this study was to investigate the interaction effects of vitamin D supplementation combined with aerobic exercises and conventional physical therapy on balance and physical performance in children with Down syndrome.

Methods

A randomised controlled trial was conducted for 38 children with Down syndrome, with ages ranging from 8 to 12 years. They were divided randomly into two groups. The control group (n=19) received conventional physical therapy and aerobic exercises, while the study group (n=19) received conventional physical therapy, aerobic exercises and vitamin D in the form of an oral daily dose of vitamin D3 400 IU (cholecalciferol). The children in both groups participated in the same physical therapy for 45 minutes, 3 days a week for 12 weeks, and undertook 15 minutes of aerobic exercise after the physical therapy sessions. Balance was evaluated by using the Biodex Stability System and physical performance was evaluated by using the 6-Minute Walk Test.

Results

All groups showed a significant improvement in the medial-lateral stability index, the anterior-posterior stability index, the overall stability index and the 6-Minute Walk Test after treatment (P<0.05). The study group showed a significant improvement in the measured variables compared with that of the control group (P<0.05).

Conclusions

Vitamin D supplements, combined with aerobic exercises and conventional physical therapy, could improve balance and physical performance in children with Down syndrome. Therefore, vitamin D and aerobic exercises should be considered as an adjunctive to physical therapy.

Associations of Serum Vitamin D Level with Sarcopenia, Non-Alcoholic Fatty Liver Disease (NAFLD), and Sarcopenia in NAFLD Among People Aged 50 Years and Older: The Korea National Health and Nutrition Examination Survey IV-V

Background: The role of serum 25-hydroxyvitamin D [25(OH)D] levels in the development of sarcopenia in non-alcoholic fatty liver disease (NAFLD) remains controversial. We investigated the association between vitamin D levels, occurrence of sarcopenia, NAFLD, and sarcopenia in NAFLD in adults aged >50 years. Methods: This study used data pertaining to 5396 adults aged >50 years (1870 men and 3526 women) from the 2008-2011 Korea National Health and Nutrition Examination Survey. Appendicular skeletal muscle mass adjusted by weight (ASM/Wt) was used to diagnose sarcopenia, and NAFLD was diagnosed using the NAFLD fat score. Results: The lowest quintile of serum 25(OH)D level (4.85-15.26 ng/mL) was associated with an increased occurrence of sarcopenia [odds ratio (OR) 2.65; 95% confidence interval (CI) 1.64-4.27], NAFLD (OR 1.82; 95% CI 1.19-2.96), and sarcopenia in NAFLD (OR 2.25; 95% CI 1.26-4.03) in men. In women, sarcopenia (OR 1.80; 95% CI 1.29-2.51) was also significantly associated with serum vitamin D levels, whereas high levels of vitamin D were not significantly related to NAFLD. Conclusions: Serum vitamin D levels are associated with sarcopenia, NAFLD, and sarcopenia in NAFLD. Vitamin D level can be a useful marker of sarcopenia and NAFLD, especially in men.

Skeletal Muscle Metabolic Alternation Develops Sarcopenia

Sarcopenia is a new type of senile syndrome with progressive skeletal muscle mass loss with age, accompanied by decreased muscle strength and/or muscle function. Sarcopenia poses a serious threat to the health of the elderly and increases the burden of family and society. The underlying pathophysiological mechanisms of sarcopenia are still unclear. Recent studies have shown that changes of skeletal muscle metabolism are the risk factors for sarcopenia. Furthermore, the importance of the skeletal muscle metabolic microenvironment in regulating satellite cells (SCs) is gaining significant attention. Skeletal muscle metabolism has intrinsic relationship with the regulation of skeletal muscle mass and regeneration. This review is to discuss recent findings regarding skeletal muscle metabolic alternation and the development of sarcopenia, hoping to contribute better understanding and treatment of sarcopenia.

Vitamin D supplementation in chronic spinal cord injury (VitD-SCI): study protocol for a randomised controlled trial

INTRODUCTION

Vitamin D insufficiency, a vitamin D status or serum 25(OH)D concentration of ≤75 nmol/L, is highly prevalent in individuals with a spinal cord injury (SCI). Vitamin D is important for the functioning of the musculoskeletal, immune and respiratory systems, which are relevant determinants of secondary health conditions in SCI. An insufficiency should be treated with vitamin D supplementation. However, there is a lack of evidence regarding the optimal dosage and duration of vitamin D supplementation for individualised and long-term management of the vitamin D status in the context of SCI. This paper presents the protocol for the vitamin D supplementation in chronic spinal cord injury (VitD-SCI) trial that aims to investigate the effect of a 12-month intake of vitamin D supplementation on vitamin D status as well as on several secondary parameters among individuals with a chronic SCI.

METHODS AND ANALYSES

The VitD-SCI trial is a randomised, placebo-controlled, double-blinded, parallel-group, superiority trial, conducted at the Swiss Paraplegic Centre. A total of 45 participants living with an SCI for at least 3 years (chronic SCI) and a vitamin D insufficiency at the first study visit, will be randomly assigned to one of three intervention groups. Participants receive either a monthly dosage of 24 000 IU or 48 000 IU vitamin D or a placebo for 12 months. Measurements taking place every 3 months include the assessment of vitamin D status (primary outcome) as well as bone mineral density, handgrip strength, fatigue, mood, pain and pressure injuries (secondary outcomes). Safety and tolerance of vitamin D supplementation will also be evaluated.

ETHICS AND DISSEMINATION

The Swiss Ethics Committee for Northwest/Central Switzerland (EKNZ, 2020-01493) and the Swiss Agency for Therapeutic Products (Swissmedic, 2020DR3150) approved this study. Findings will be disseminated through peer-reviewed publications.

TRIAL REGISTRATION NUMBERS

NCT04652544 and SNCTP000004032.

Effects of daily 1,000-IU vitamin D-fortified milk intake on skeletal muscle mass, power, physical function and nutrition status in Japanese

An intervention study was conducted to investigate the effects of daily 1,000-IU vitamin D-fortified milk intake on skeletal muscle mass, power, physical function and nutrition status in 26 healthy people and 8 older adults living in a nursing home. The serum 25-hydroxyvitamin D [25(OH)D] level was 13.4 ± 0.8 ng / mL and it markedly increased to 29.6 ± 0.9 ng / mL after daily 1000-IU vitamin D-fortified milk intake for 6 months. Handgrip strength (kg) also significantly increased in the 21-50 years and total groups, and male subjects, and the timed up and go test significantly improved in the 21-50 years and total groups, and female subjects after 6-month vitamin D intake. However, there were no significant differences between baseline and post-treatment in the Barthel Index (BI), walking speed (m / sec) or skeletal muscle mass (kg, % of BW, kg / m2). Therefore, the present study suggested that vitamin D-fortified milk intake is effective at improving muscle strength and physical function in Japanese, although further studies are needed, particularly for older adults. J. Med. Invest. 68 : 249-255, August, 2021.

Effects of Vitamin D in Post-Exercise Muscle Recovery. A Systematic Review and Meta-Analysis

Vitamin D is a key micronutrient modulating function and health in skeletal muscle. Therefore, we sought to systematically review the role of vitamin D in muscle recovery. A search in different databases (PubMed/MEDLINE, WOS, Google Scholar, and Scopus) was carried out following PRISMA^® and PICOS. The search period was from inception to April 2020. Changes in post-exercise muscle damage were quantified comparing experimental group vs. placebo in each study by using number of participants, standardized mean difference (SMD), and standard error of the SMD. Hedges’s g was used to calculate the SMDs for each study group and biased by the inverse of variance that allows calculating an overall effect and the 95% confidence interval (CI). The net vitamin D supplementation effect was calculated by subtracting the placebo SMD from SMD of the experimental group. The DerSimonian and Laird method was used as a random effect model, taking into account that the effect of vitamin D on muscular damage may vary according to the dose administered and additional moderators. Six studies were selected. In conclusion, regarding circulating levels of muscle biomarkers and additional limitations of the studies, it cannot be concluded that vitamin D supplementation exerts an effect in post-exercise muscle recovery. Likely, the anti-inflammatory action of vitamin D is quicker than the recovery of tissue structure and function. This aspect is pending verification in future research.