Vitamin D receptor expression in human muscle tissue decreases with age

Pharmacological targeting of age-related changes in skeletal muscle tissue

Sarcopenia, the age-related loss of skeletal muscle mass and function, increases the risk of developing chronic diseases in older individuals and is a strong predictor of disability and death. Because of the ongoing demographic transition, age-related muscle weakness is responsible for an alarming and increasing contribution to health care costs in Western countries. Exercise-based interventions are most successful in preventing the decline in skeletal muscle mass and in preserving or ameliorating functional capacities with increasing age. However, other treatment options are still scarce. In this review, we explore currently applied nutritional and pharmacological approaches to mitigate age-related muscle wasting, and discuss potential future therapeutic avenues.

THE ASSOCIATION BETWEEN VITAMIN D LEVELS AND HANDGRIP STRENGTH IN ELDERLY MEN

CONTEXT

Vitamin D is a steroid hormone that acts by binding to the vitamin D receptor (VDR) found in many tissues. According to the long-term mechanism, vitamin D causes the proliferation and differentiation of muscle cells by gene transcription.

OBJECTIVE

We aimed to evaluate the relationship between muscle strength and serum vitamin D levels in elderly men.

DESIGN

Cross-sectional study.

SUBJECTS AND METHODS

Male patients over age 50 were included in the study. Study population was divided into 2 groups with handgrip strength according to body mass index, either as subjects with weak or with normal handgrip strength test (HGST). Vitamin D levels and other variables compared between weak and normal groups.

RESULTS

Vitamin D level of weak and normal groups were 7.5 (3-19.9) μg/L, and 11.6 (11.6-34.9) μg/L, which means significant reduced vitamin D levels in weakness group (p=0.01). Vitamin D levels were significantly correlated with HGST levels (r:0.362, p=0.001). Vitamin D levels were found to be an independent predictor of weakness according to HGST in logistic regression analysis (OR: 0.453, 95% Cl:0.138-0.769, p=0.05).

CONCLUSIONS

Low vitamin D level is an independent risk factor for muscle weakness in men aged more than 50 years. Therefore, vitamin D levels should be screened and early replacement should be initiated for the sake of improvement of muscle strength in elderly subjects that vulnerable for frailty.

Obesity and leptin influence vitamin D metabolism and action in human marrow stromal cells

Obesity is associated with low serum 25-hydroxyvitamin D [s25(OH)D], high serum leptin, and generally high bone mineral density (BMD). Human Marrow Stromal Cells (hMSCs) differentiate to osteoblasts and are both a target and source of vitamin D metabolites in bone marrow. There is no information about the influence of obesity on vitamin D metabolism and osteoblastogenesis in hMSCs and little about direct effects of leptin on hMSCs. In this study, we tested the hypotheses that 1) obesity has an influence on the ex vivo constitutive expression of vitamin D-hydroxylase genes in hMSCs, and 2) recombinant human (rh) Leptin regulates the D-hydroxylases and promotes osteoblastogenesis in hMSCs. In a cohort of female subjects undergoing joint replacement surgery, the effects of Body Mass Index (BMI) and Fat Mass Index (FMI) on BMD T-scores and s25(OH)D were evaluated. hMSCs were isolated from bone tissues discarded during surgery. The direct effects of rh-Leptin on osteoblast differentiation and D-related genes in hMSCs were examined in vitro. There were positive correlations for BMD T-score of femoral neck and spine with BMI and FMI. Serum 25(OH)D levels in obese subjects were 71% of that in non-obese counterparts (p = 0.001). hMSCs from obese women had higher constitutive expression of CYP27A1/25-hydroxylase and vitamin D receptor. Those findings raised the mechanistic question of how obesity could influence vitamin D metabolism and osteoblast differentiation in hMSCs. Treating hMSCs with rh-Leptin in vitro significantly stimulated osteoblastogenesis. In addition, leptin downregulated CYP24A1 and upregulated CYP27B1, CYP27A1 and VDR, which play vital roles in vitamin D metabolism. Furthermore, co-treatment with leptin and vitamin D₃ metabolites promoted ALP activity compared with either alone. This research demonstrates links between obesity, vitamin D metabolism, and osteoblastogenesis by which leptin's direct effects on D-metabolism and osteoblast differentiation in hMSCs may protect bone from low s25(OH)D in obese subjects.

Novel Insights on Intake of Fish and Prevention of Sarcopenia: All Reasons for an Adequate Consumption

Sarcopenia is defined as a syndrome characterized by progressive and generalized loss of skeletal muscle mass and strength and it is diagnosed by measurements of muscle mass, muscle strength, and physical performance. Sarcopenia affects quality of life and is associated with several adverse health effects. Muscle decline is aggravated by a sedentary lifestyle and can be prevented through proper nutrition, together with adequate physical activity. Fish contains biologically active compounds, such as omega-3 polyunsaturated fatty acids, proteins, vitamin D, magnesium, and carnitine, which are able to intervene positively on muscle metabolism. This narrative literature review was performed to evaluate evidence regarding the actual benefit of fish consumption in the prevention of sarcopenia and the positive action on the muscle mass of the biological compounds present in fish. The results demonstrated that fish consumption has a protective and anti-inflammatory function on skeletal muscle and that its biologically active compounds help to maintain good muscle performance, preventing sarcopenia. Considering the nutritional and health benefits, elderly with sarcopenia should consume at least three servings per week of fish in order to have a minimum intake of 4-4.59 g daily of omega 3, and reaching the 50% RDA in Vitamin E and D. High biological value of proteins in 150 g of fish and its high available magnesium (20% of RDA in 150 g of fish) are an added value that could suggest fish as a "functional food" in order to prevent and treat sarcopenia.

Supplemental vitamin D3 does not affect musculoskeletal or psychomotor performance in college aged males

The experiment examined the effects 4 weeks of vitamin D (Vit D) supplementation versus placebo on musculoskeletal and psychomotor performance. Thirty-two college age males (Age: 22 ± 4 y, Height: 177.7 ± 8.3 cm, Weight: 81.5 ± 14.6 kg, BF%: 19.6 ± 7.9, Vit D: 20.0 ± 7.2 ng/ml). Participants were assigned to group (Vit D vs placebo) and remained blind throughout the study. The treatments were 4000 IU of Vit D3 or placebo (dextrose) administered daily for 4 weeks. The participants underwent baseline testing for isometric strength, explosive ability and psychomotor performance, which was repeated at week 2 and week 4. Isometric tests consisted of an Isometric Mid Thigh Pull on a Force Plate (IMTP) and an upper body isometric test (UBIST) using a load cell. Peak force during a countermovement jump (CMJ) was also determined via force plate. A psychomotor vigilance test (PVT) was used to measure sustained reaction time. Analysis of the UBIST data did not reveal a significant group × time interaction (p = 0.14; Vit D pre: 553.7 ± 168.3 N, post: 585.5 ± 150.2 N; Placebo pre: 677.7 ± 182.3 N, post: 649.8 ± 236.9 N). For IMTP no significant group × time interaction (p = 0.83; Vit D pre: 2596.4 ± 342.3 N, post: 2606.9 ± 378.3 N; Placebo pre: 2684.0 ± 432.9 N, post: 2762.6 ± 440.4 N) was found. CMJ analysis did not reveal interaction effects for group × time (p = 0.21; Vit D pre: 4429.7 ± 1619.0 N, post: 4938.5 ± 2374.8 N; Placebo pre: 5537.3 ± 3027.0 N, post: 6266.9 ± 4577.3 N). For PVT (mean reaction time) there was no significant interaction effects for group × time (p = 0.35; Vit D pre: 0.304 ± 0.041 sec, post: 0.301 ± 0.053 sec; Placebo pre: 0.295 ± 0.044 sec, post: 0.284 ± 0.029 sec). In conclusion, four weeks of Vit D supplementation was not effective in increasing musculoskeletal or psychomotor performance.

Propionate promotes vitamin D receptor expression via yes-associated protein in rats with short bowel syndrome

Vitamin D deficiency and refractory osteoporosis are common complications in patients with short bowel syndrome (SBS). The symptom of bone loss is not effectively alleviated, even after the oral administration of vitamin D in SBS patients who had been weaned off parenteral nutrition. In this study, we aimed to investigate the effect of propionate on the expression of the vitamin D receptor (VDR) in the small intestine of rats with SBS. Firstly, IEC-6 (intestinal epithelioid cell line No. 6) cells were incubated in vitro with 1 mM sodium propionate for 24 h. This resulted in a significant increase in the expression of VDR and yes-associated protein (YAP) compared with that in the control group. Transfection of IEC-6 cells with YAP siRNA significantly down-regulated the expression of VDR. By contrast, after incubating IEC-6 cells with lysophosphatidic acid, an agonist of YAP, upregulation of VDR and YAP was observed. Next, we investigated whether this effect occurs in vivo. Five-week-old male Sprague-Dawley rats underwent 80% small bowel resection to establish an SBS model. Rats treated with 1% w/v sodium propionate had high levels of VDR and YAP expression in the intestine and intestinal adaptation was clearly observed compared to the control group. However, these effects were blocked by intraperitoneal injection of verteporfin. Thus, this study showed that propionate promoted VDR expression in the intestine via the activity of YAP, both in vitro and in vivo. Moreover, propionate was shown to play an active role in postoperative intestinal adaptation in SBS rats.

Vitamin D and Muscle Sarcopenia in Aging

Sarcopenia, the age-dependent decline of muscle mass and performance, is a common condition among elderly population and is related to numerous adverse health outcomes. Due to the effect of sarcopenia on quality of life, disability, and mortality, a greater awareness is important in order to correctly recognize the condition both in community and geriatric settings. Research on sarcopenia prevention and treatment is growing quickly, but many questions are still unanswered. The core of the sarcopenia state includes quantitative and qualitative declines of skeletal muscle. These two aspects should therefore be considered when designing and examining preventive and therapeutic interventions. The role of vitamin D in skeletal muscle metabolism has been highlighted in recent years. The interest arises from the important findings of studies indicating multiple impacts of vitamin D on this tissue, which can be divided into genomic (direct impacts) and non-genomic impacts (indirect impacts). Another important dimension to be considered in the study of vitamin D and muscle fiber metabolism is associated with different expressions of the vitamin D receptor, which differs in muscle tissue, depending on age, gender, and pathology. Vitamin D inadequacy or deficiency is related to muscle fiber atrophy, elevated risk of chronic musculoskeletal pain, sarcopenia, and falls. This review describes the effect of vitamin D in skeletal muscle tissue function and metabolism and includes discussion of possible mechanisms in skeletal muscle.

Older Age Is Associated with Decreased Levels of VDR, CYP27B1, and CYP24A1 and Increased Levels of PTH in Human Parathyroid Glands

Parathyroid glands contain the vitamin D receptor (VDR) and 25-hydroxyvitamin D-1α-hydroxylase (CYP27B1) and 24-hydroxylase (CYP24A1), which catalyze the production and degradation of 1,25-dihydroxyvitamin D [1,25(OH)₂D], respectively. Previous studies have shown that the serum level of intact parathyroid hormone (iPTH) increases with age. We hypothesized that the expression of CYP27B1 or VDR in parathyroid glands decreases with age, which might account for the increased serum levels of iPTH due to decreased suppression of parathyroid hormone (PTH) secretion by 1,25(OH)₂D in older people. To test this hypothesis, we examined relative expression levels of VDR, CYP27B1, CYP24A1, and PTH in specimens from parathyroid glands unintentionally removed during thyroidectomy for 70 patients varying in age from 10 to 70 years. The results showed that there was an inverse correlation between age and VDR, CYP27B1, and CYP24A1 expression (p < 0.05). A significant positive correlation between PTH expression levels and age was also observed (p < 0.05). These data indicate that older age is associated with decreased levels of VDR, CYP27B1, and CYP24A1 and increased levels of PTH in human parathyroid glands.

Four months vitamin D supplementation to vitamin D insufficient individuals does not improve muscular strength: A randomized controlled trial

Main objective

The inconsistent results on the effects of vitamin D on muscle strength reported by intervention trials may partly be explained by inclusion of vitamin D sufficient individuals. The main objective was to study whether vitamin D supplementation will improve muscle strength in men and women with low serum vitamin D status, as measured by 25-hydroxyvitamin D (25(OH)D) at baseline.

Methods

417 men and women aged 40–80 years were included and randomized to receive a loading dose of 100 000 IU (2500 ug) vitamin D₃ followed by 20 000 IU (500 ug)/week, or placebo. Muscle strength was tested by dynamometers at baseline and after four months.

Results

Serum 25(OH)D levels increased from 32.6±11.1 nmol/l to 88.8±19.4 nmol/l (p<0.01) in the vitamin D group, while remaining low in the placebo group (baseline and final levels at 35.1±13.6 nmol/l and 30.7 ±9.7 nmol/l respectively). Muscle strength (hip flexion, biceps flexion, pectorals and handgrip strength) did not change in any of the groups. The results were the same in analyses stratified on sex, 25(OH)D above/below 25 nmol/L (10 ng/ml); smoking status; and BMI above/below 27 kg/m².

Conclusion

These data does not support vitamin D supplementation for improving muscle strength.

The inter-relationship between marginal vitamin D deficiency and muscle

PURPOSE OF REVIEW

We review the recent literature on the interplay between mild vitamin D deficiency and skeletal muscle strength and performance.

RECENT FINDINGS

Preclinical studies indicate that vitamin D is important in muscle proliferation, differentiation and mitochondrial function, whereas some epidemiological studies demonstrate associations with muscle strength and low physical performance. Recent studies have implicated vitamin D deficiency in the development of frailty and sarcopenia in the older population. Some small studies have assessed its impact on muscle function in special circumstances such as elite sport and critical illness. Advances in liquid chromatography/mass spectrometry technologies have allowed the inter-relationships between the vitamin D metabolome and muscle phenotype to be characterized. There is evidence of distinct effects on human skeletal muscle gene expression between vitamin D metabolites.

SUMMARY

Large-scale clinical trials with well defined cohorts and outcomes are needed to provide clinically meaningful insights into this area. Care should be taken to stratify participants by vitamin D status at baseline and over follow-up in addition to observing a range of measures of muscle function.

Nutritional strategies for maintaining muscle mass and strength from middle age to later life: A narrative review

Progressive age-related reductions in muscle mass and strength (sarcopenia) can cause substantial morbidity. This narrative review summarizes evidence of nutritional interventions for maintaining muscle mass and strength from midlife through old age. PubMed and Cochrane databases were searched to identify studies of dietary intake and nutritional interventions for sustaining muscle mass and strength. The benefits of progressive resistance training with and without dietary interventions are well documented. Protein and amino acid (particularly leucine) intake should be considered, and supplementation may be warranted for those not meeting recommended intakes. Vitamin D receptors are expressed in muscle tissue; meta-analyses have shown that vitamin D benefits muscle strength. Data suggest that milk and other dairy products containing different bioactive compounds (i.e. protein, leucine) can enhance muscle protein synthesis, particularly when combined with resistance exercise. Omega-3 s can improve muscle mass and strength by mediating cell signaling and inflammation-related oxidative damage; no studies were specifically conducted in sarcopenia. Low-dose antioxidants (e.g. vitamins C and E) can protect muscle tissue from oxidative damage, but relevant studies are limited. Magnesium is involved with muscle contraction processes, and data have shown benefits to muscle strength. Acidogenic diets increase muscle protein breakdown, which is exacerbated by aging. Alkalizing compounds (e.g. bicarbonates) can promote muscle strength. Small studies of probiotics and plant extracts have generated interest, but few large studies have been conducted. Based on available data, dietary and supplemental interventions may add to the benefits of exercise on muscle mass and strength; effects independent of exercise have not been consistently shown.

Vitamin D Deficiency and Sarcopenia in Older Persons

Vitamin D deficiency is a common health problem worldwide, in particular among older people. Vitamin D regulates and modulates the physiology and function of multiple human systems, including the skeletal muscle. The effect of vitamin D on the muscle has been widely investigated, suggesting that this hormone can stimulate the proliferation and differentiation of skeletal muscle fibers, maintaining and improving muscle strength and physical performance. Older persons have a higher prevalence of low Vitamin D levels as a consequence of low dietary intake and reduced ultraviolet irradiation of the skin. Therefore, older people with vitamin D deficiency might be at risk of sarcopenia, a geriatric syndrome characterized by the progressive loss of skeletal muscle mass and strength often complicated by adverse events, such as falls, disability hospitalization and death. Several randomized clinical trials have been conducted to investigate the effect of oral vitamin D supplementation in older patients to prevent or treat sarcopenia, but results are still controversial. In this narrative review we summarize the biological, clinical and epidemiological evidence supporting the hypothesis of a causal association between Vitamin D deficiency and an increased risk of sarcopenia in older people.

[How does vitamin D influence body composition, sarcopenia and lifespan in older persons? A retrospective study of nine years]

Introduction

Background: hypovitaminosis D has a prevalence of 50,4% in older persons. This population has grown globally in an impressive way during the last 20 years. In addition, the deficiency of vitamin D (< 30 ng/ml) could raise the risk of mortality in this population. Objectives: to know whether vitamin D levels less than 30 ng/ml have an impact on mortality for overall causes, cardiovascular causes, cancer or injuries (falls) in a follow-up period of nine years in elderly subjects. Methods: a retrospective longitudinal study with nine years period of observation; 418 elderly subjects were followed, and they were recruited in 2004 to participate in a study about vitamin D supplementation and muscle strength. Results: vitamin D levels below 30 ng/dl increase by almost three times the probability of dying (OR = 2.77, IC = 1.81-3.85), while the same level of vitamin D is associated with a double risk of dying from cardiovascular causes (OR = 1.78, CI = 1.21-2.09) in the unadjusted model. For cancer mortality and falls, no significant results were obtained. Vitamin D would not act as a protective factor against mortality. Conclusions: vitamin D levels less than 30 ng/ml could be a risk factor for general mortality.

Altered gene and protein expressions of vitamin D receptor in skeletal muscle in sarcopenic patients who sustained distal radius fractures

Despite the presence of vitamin D receptor (VDR) in skeletal muscle cells, the relationship between VDR expressions and muscle mass or function has not been well studied. The purpose of this study was to compare VDR gene and protein expression in the forearm muscle between sarcopenic and non-sarcopenic individuals who have sustained distal radius fractures. Twenty samples of muscle tissue from sarcopenic patients (mean age 63.4 ± 8.1 years) and 20 age- and sex-matched control tissues (62.1 ± 7.9 years) were acquired from the edge of dissected pronator quadratus muscle during surgery for distal radius fractures. The mRNA expression levels of VDR as well as the myokines of interest that may be associated with muscle mass change (myogenin and myostatin) were analyzed with real-time quantitative reverse transcription polymerase chain reaction (qRT-PCR). In addition, Western blot assay and immunohistochemistry for VDR were performed. Sarcopenic patients showed a significantly lower level of gene expression for VDR and myogenin, but a greater level of gene expression for myostatin than the controls according to qRT-PCR analysis. The density of VDR protein expressions was 2.1 times greater, while that of myostatin was 2.6 times lower, in the control group than in the sarcopenic group according to Western blot analysis. On immunohistochemical analysis, the density of the cells expressing VDR was significantly decreased in the sarcopenic patients. Sarcopenic patients who sustained distal radius fractures presented lower vitamin D receptor gene and protein expression in skeletal muscles compared to non-sarcopenic individuals.

Efficacy of Nutritional Interventions as Stand-Alone or Synergistic Treatments with Exercise for the Management of Sarcopenia

Sarcopenia is an age-related and accelerated process characterized by a progressive loss of muscle mass and strength/function. It is a multifactorial process associated with several adverse outcomes including falls, frailty, functional decline, hospitalization, and mortality. Hence, sarcopenia represents a major public health problem and has become the focus of intense research. Unfortunately, no pharmacological treatments are yet available to prevent or treat this age-related condition. At present, the only strategies for the management of sarcopenia are mainly based on nutritional and physical exercise interventions. The purpose of this review is, thus, to provide an overview on the role of proteins and other key nutrients, alone or in combination with physical exercise, on muscle parameters.

The effects of vitamin D supplementation on muscle function among postmenopausal women: a systematic review and meta-analysis of randomized controlled trials

The loss of muscle mass and its strength is one of the most critical changes in aging which is associated with an increased risk of falls, osteoporotic fractures and mobility disability. Vitamin D, with its extra-skeletal benefits, might improve muscle function in elderly. The current systematic review and meta-analysis of randomized controlled trials (RCTs) was conducted to summarize available relevant data and determine the effect of vitamin D supplementation on muscle function among postmenopausal women. We reached databases including; Cochrane library, Embase, PubMed, and Web of Science database until the end of May 2018 to identify relevant published RCTs. Heterogeneity among included studies was assessed using Q-test and I2 statistics. Random-effect model was applied to pool data and weighted mean difference (WMD) was calculated representing summary effect size. Outcomes of interest included the effects of vitamin D supplementation on hand grip strength (HGS), back muscle strength (BMS), and Timed Up and Go (TUG). Twelve RCTs out of 1739 potential reports were included in our meta-analysis. The pooled findings showed that vitamin D supplementation had no significant effect on HGS (WMD -0.03 kilogram (Kg); 95 % CI, -0.26, 0.20; P=0.78), BMS (WMD 7.21 newton (N); 95 % CI, -5.98, 20.40; P=0.28), and TUG (WMD 0.01 second (S); 95 % CI, -0.17, 0.18; P=0.93) in postmenopausal women. Overall, the current meta-analysis showed that taking vitamin D supplementation by postmenopausal women did not affect markers of muscle function. Further studies are required to confirm the effect of vitamin D supplementation on markers of muscle function.

Vitamin D, Skeletal Muscle Function and Athletic Performance in Athletes-A Narrative Review

The active form of vitamin D (calcitriol) exerts its biological effects by binding to nuclear vitamin D receptors (VDRs), which are found in most human extraskeletal cells, including skeletal muscles. Vitamin D deficiency may cause deficits in strength, and lead to fatty degeneration of type II muscle fibers, which has been found to negatively correlate with physical performance. Vitamin D supplementation has been shown to improve vitamin D status and can positively affect skeletal muscles. The purpose of this study is to summarize the current evidence of the relationship between vitamin D, skeletal muscle function and physical performance in athletes. Additionally, we will discuss the effect of vitamin D supplementation on athletic performance in players. Further studies are necessary to fully characterize the underlying mechanisms of calcitriol action in the human skeletal muscle tissue, and to understand how these actions impact the athletic performance in athletes.

Mechanisms of vitamin D action in skeletal muscle

Vitamin D receptor expression and associated function have been reported in various muscle models, including C2C12, L6 cell lines and primary human skeletal muscle cells. It is believed that 1,25-hydroxyvitamin D3 (1,25(OH)2D3), the active form of vitamin D, has a direct regulatory role in skeletal muscle function, where it participates in myogenesis, cell proliferation, differentiation, regulation of protein synthesis and mitochondrial metabolism through activation of various cellular signalling cascades, including the mitogen-activated protein kinase pathway(s). It has also been suggested that 1,25(OH)2D3 and its associated receptor have genomic targets, resulting in regulation of gene expression, as well as non-genomic functions that can alter cellular behaviour through binding and modification of targets not directly associated with transcriptional regulation. The molecular mechanisms of vitamin D signalling, however, have not been fully clarified. Vitamin D inadequacy or deficiency is associated with muscle fibre atrophy, increased risk of chronic musculoskeletal pain, sarcopenia and associated falls, and may also decrease RMR. The main purpose of the present review is to describe the molecular role of vitamin D in skeletal muscle tissue function and metabolism, specifically in relation to proliferation, differentiation and protein synthesis processes. In addition, the present review also includes discussion of possible genomic and non-genomic pathways of vitamin D action.

The Effect of Yearly-Dose Vitamin D Supplementation on Muscle Function in Mice

Supplementation with vitamin D helps to alleviate weakness and fatigue seen with deficiency. However, large bolus doses appear to worsen the risk of falls. Whether this occurs as a direct result of muscle weakness is currently unknown. Thus, the aims of this study were to examine the muscle function following administration of high doses of vitamin D. Given the safety issues associated with bolus doses, experiments were conducted on C57BL6 mice. Mice at eight weeks of age with otherwise normal levels of vitamin D were supplemented for four weeks with a high dose (HIGH; n = 12) of vitamin D (20000 IU/kg food) designed to provide a year's worth of vitamin D. These mice were compared to another group who received that same yearly dose in a single bolus i.p. injection (YEAR; n = 12). Mice provided with standard mouse chow, which contained 1000 IU/kg food, and injected with the vitamin D vehicle were used as controls (CON; n = 16). Force and fatigue properties of hind limb fast- and slow-twitch muscles were measured. CON animals ingested vitamin D consistent with typical human supplementation. HIGH animals consumed significantly more food than the CON animals, such that they ingested more than a year's worth of vitamin D in four weeks. Despite this, there were few differences in the muscle function compared with CON. YEAR animals demonstrated lower absolute and relative forces in both muscles compared to the HIGH animals, as well as lower force during fatigue and early recovery. Large bolus doses of vitamin D appear to have detrimental effects on the skeletal muscle function, likely being a contributor to increased risk of falls observed with similar doses in humans. Mice ingesting the same amount over four weeks did not demonstrate the same deleterious effects, suggesting this may be a safe way to provide high vitamin D if required.

Vitamin D is related to handgrip strength in adult men aged 50 years and over: A population study from the TCLSIH cohort study

OBJECTIVE

Handgrip strength (HGS) begins an accelerating decline around 50 years. Many of the studies performed in old adults have demonstrated a significant relationship between vitamin D and HGS, but the studies performed in participants with a broad age range have yielded conflicting results. The purpose of the study was to investigate the relationship between vitamin D and HGS using age 50 as a specific cut-off.

DESIGN

Population-based, cross-sectional study.

PARTICIPANTS

Totally 5102 participants (2911 males, 2191 females) from the TCLSIH Cohort.

MEASUREMENTS

Serum concentration of 25-hydroxyvitamin D (25(OH)D) was measured using an enzyme immunoassay. We divided participants into quartiles according to 25(OH)D, and the ranges for increasing quartiles were as follows: (males [≥50 years]: 10.94-31.85, 31.88-43.01, 43.20-56.06, 56.20-143.0; males [<50 years]: 11.11-34.68, 34.71-46.91, 46.96-59.45, 59.50-143.7; females [≥50 years]: 7.21-30.01, 30.02-40.18, 40.21-52.44, 52.49-275.4; females [<50 years]: 5.29-28.91, 28.92-40.19, 40.20-51.90, 51.91-140.2). HGS was measured with a hydraulic hand-held dynamometer. Analysis of covariance was employed to explore the relationship.

RESULTS

Among males aged above 50 years, the means (95% confidence interval) for HGS per body weight across the categories of serum 25(OH)D concentration were 0.523 (0.430-0.638), 0.545 (0.447-0.664), 0.543 (0.446-0.661), 0.546 (0.449-0.664) (P_trend  < 0.01) after adjustment for potential confounding factors. However, no relationships were observed between serum 25(OH)D concentration and HGS in males aged below 50 years and females in the whole age range.

CONCLUSIONS

Serum 25(OH)D concentration was significantly related to HGS in males aged above 50 years, independent of confounding factors. Future studies are needed to clarify the age and sex relationship between serum 25(OH)D concentration and HGS.

Effect of vitamin D supplementation on upper and lower limb muscle strength and muscle power in athletes: A meta-analysis

BACKGROUND

Vitamin D may play a role in skeletal muscle because of the discovery of VDR in skeletal muscle. However, vitamin D deficiency is a global problem, including athletes. Studies examining the effect of vitamin D supplementation on muscle function in athletes have inconsistent results. Therefore, we aimed to quantitatively summarize the evidence for the effect of vitamin D supplementation on skeletal muscle strength and explosive power of athletes using a meta-analysis.

METHODS

PubMed, EMBASE, Cochrane Library, and Web of Science were searched for studies to identify randomized controlled trials or controlled trials meeting the inclusion criteria. By a meta-analysis, effect sizes (standardized mean differences, SMD) with 95% confidence intervals (CI) was calculated to compare reported outcomes across studies, I2 index was used to assessing heterogeneity, and heterogeneity factors were identified by regression analysis. The potential publication and sensitivity analyses were also assessed.

RESULTS

Eight RCTs involving 284 athletes were included. The protocols used to evaluate the muscle strength of athletes were inconsistent across the included studies, and muscle explosive power was assessed via vertical jump tests. The results indicated that vitamin D supplementation had no impact on overall muscle strength outcomes (SMD 0.05, 95% CI: -0.39 to 0.48, p = 0.84). In subgroup analysis, vitamin D supplementation had an effect on lower-limb muscle strength (SMD 0.55, 95% CI:0.12 to 0.98, p = 0.01) but not upper-limb muscle strength (SMD -0.19, 95% CI:-0.73 to 0.36, p = 0.50) or muscle explosive power (SMD 0.05, 95% CI:-0.24 to 0.34, p = 0.73). Vitamin D supplementation was more effective for athletes trained indoors (SMD 0.48, 95% CI:0.06 to 0.90, p = 0.02).

CONCLUSIONS

Vitamin D supplementation positively affected lower limb muscle strength in athletes, but not upper limb muscle strength or muscle power. Different muscle groups and functions may respond differently to vitamin D supplementation. Additional studies should focus on determining the appropriate vitamin D supplementation methods and optimal serum 25(OH)D levels for athletes.

REGISTRATION

The protocol for our study is registered in the international prospective register of systematic reviews (PROSPERO registration number CRD42016045872).

Current vitamin D status in European and Middle East countries and strategies to prevent vitamin D deficiency: a position statement of the European Calcified Tissue Society

Vitamin D deficiency (serum 25-hydroxyvitamin D (25(OH)D) <50 nmol/L or 20 ng/mL) is common in Europe and the Middle East. It occurs in <20% of the population in Northern Europe, in 30-60% in Western, Southern and Eastern Europe and up to 80% in Middle East countries. Severe deficiency (serum 25(OH)D <30 nmol/L or 12 ng/mL) is found in >10% of Europeans. The European Calcified Tissue Society (ECTS) advises that the measurement of serum 25(OH)D be standardized, for example, by the Vitamin D Standardization Program. Risk groups include young children, adolescents, pregnant women, older people (especially the institutionalized) and non-Western immigrants. Consequences of vitamin D deficiency include mineralization defects and lower bone mineral density causing fractures. Extra-skeletal consequences may be muscle weakness, falls and acute respiratory infection, and are the subject of large ongoing clinical trials. The ECTS advises to improve vitamin D status by food fortification and the use of vitamin D supplements in risk groups. Fortification of foods by adding vitamin D to dairy products, bread and cereals can improve the vitamin D status of the whole population, but quality assurance monitoring is needed to prevent intoxication. Specific risk groups such as infants and children up to 3 years, pregnant women, older persons and non-Western immigrants should routinely receive vitamin D supplements. Future research should include genetic studies to better define individual vulnerability for vitamin D deficiency, and Mendelian randomization studies to address the effect of vitamin D deficiency on long-term non-skeletal outcomes such as cancer.

Mechanisms of vitamin D on skeletal muscle function: oxidative stress, energy metabolism and anabolic state

PURPOSE

This review provides a current perspective on the mechanism of vitamin D on skeletal muscle function with the emphasis on oxidative stress, muscle anabolic state and muscle energy metabolism. It focuses on several aspects related to cellular and molecular physiology such as VDR as the trigger point of vitamin D action, oxidative stress as a consequence of vitamin D deficiency.

METHOD

The interaction between vitamin D deficiency and mitochondrial function as well as skeletal muscle atrophy signalling pathways have been studied and clarified in the last years. To the best of our knowledge, we summarize key knowledge and knowledge gaps regarding the mechanism(s) of action of vitamin D in skeletal muscle.

RESULT

Vitamin D deficiency is associated with oxidative stress in skeletal muscle that influences the mitochondrial function and affects the development of skeletal muscle atrophy. Namely, vitamin D deficiency decreases oxygen consumption rate and induces disruption of mitochondrial function. These deleterious consequences on muscle may be associated through the vitamin D receptor (VDR) action. Moreover, vitamin D deficiency may contribute to the development of muscle atrophy. The possible signalling pathway triggering the expression of Atrogin-1 involves Src-ERK1/2-Akt- FOXO causing protein degradation.

CONCLUSION

Based on the current knowledge we propose that vitamin D deficiency results from the loss of VDR function and it could be partly responsible for the development of neurodegenerative diseases in human beings.

Vitamin D Status in Women with Pelvic Floor Disorders: A Meta-Analysis of Observational Studies

The current evidence regarding the association between vitamin D status and pelvic floor disorder (PFD) are inconclusive. This meta-analysis was aimed to summarize existing data demonstrating the association between Vitamin D status and PFD using published observational studies. All national and international databases including Web of Science, PubMed, Google Scholar, and Scopus were searched up until January 30, 2018, and related published studies retrieved for meta-analysis. The effect sizes of Vitamin D status were presented as standardized mean difference (SMD) with 95% confidence interval (CI), using random-effect models and inverse variance method. The Cochran Q statistic and I 2 tests were used to evaluate the heterogeneity across included studies. Seven studies with 3219 women were included our meta-analysis. There was heterogeneity existing among included studies (I 2 = 96.4%, P < 0.001), so a random-effect model was used. The findings of this meta-analysis revealed that the mean serum Vitamin D levels in women with PFD were significantly lower than healthy women (SMD -0.60; 95% CI, -1.06, -0.13; P = 0.01). This meta-analysis demonstrates lower levels of serum Vitamin D in women with PFD rather than healthy women. Additional prospective studies regarding the association between Vitamin D status and PFD are required to confirm our findings.

The Relationship Between Serum 25-Hydroxyvitamin D Levels and Physical Performance in Community-Dwelling Older Adults

Background

Vitamin D deficiency is a risk factor for musculoskeletal health in older adults. While many studies have explored the relationship between vitamin D deficiency and fractures, few have examined the relationship between vitamin D and physical performance. We, therefore, sought to evaluate the relationship between serum 25-hydroxyvitamin D [25(OH)D] levels and physical performance in community-dwelling older adults.

Methods

A single-center, cross-sectional study was performed using data collected from 132 individuals aged 60 years or older who were living independently and who participated in the National Health Insurance Service health check-up between May and December 2016. Physical performance was assessed using a short physical performance battery (SPPB). Linear regression was used to examine the association between 25(OH)D levels and physical performance after adjustment for sociodemographic variables, behavioral characteristics, and body mass index.

Results

Approximately 36.5% of male and 50.7% of females had vitamin D levels indicative of deficiency (serum 25(OH)D <20.0 ng/mL). 25(OH)D levels were significantly associated with the chair stand SPPB scores in male and females but not with those of the walking and balance tests. After adjustment for potential confounders, there remained a linear association between 25(OH)D levels and the chair stand test for both sexes.

Conclusion

Lower serum 25(OH)D levels were associated with poor physical performance (chair stand score) among community-dwelling older adults in Korea. Further prospective studies are needed to verify these results.

Variations in the vitamin D receptor gene are not associated with measures of muscle strength, physical performance, or falls in elderly men. Data from MrOS Sweden

The vitamin D receptor (VDR) has been proposed as a candidate gene for several musculoskeletal phenotypes. However, previous results on the associations between genetic variants of the VDR with muscle strength and falls have been contradictory. The MrOS Sweden survey, a prospective population-based cohort study of 3014 elderly men (mean age 75 years, range 69-81) offered the opportunity to further investigate these associations. At baseline, data were collected on muscle strength and also the prevalence of falls during the previous 12 months. Genetic association analysis was performed for 7 Single Nucleotide Polymorphisms (SNPs), covering the genetic region surrounding the VDR gene in 2924 men with available samples of DNA. Genetic variations in the VDR were not associated with five different measurements of muscle strength or physical performance (hand grip strength right and left, 6 m walking test (easy and narrow) and timed-stands test). However, one of the 7 SNPs of the gene for the VDR receptor, rs7136534, was associated with prevalence of falls (33.6% of the AA, 14.6% of the AG and 16.5% of the GG allele). In conclusion, VDR genetic variants are not related to muscle strength or physical performance in elderly Swedish men. The role of the rs7136534 SNP for the occurrence of falls is not clear.

The effect of vitamin D supplementation on lower-extremity power and function in older adults: a randomized controlled trial

Background

The effect of vitamin D supplementation on muscle function in older adults has been tested in randomized trials with mixed results, which may be due to differences in the study participant characteristics, including baseline vitamin D status. The results of 2 meta-analyses of randomized trials suggested a beneficial effect of vitamin D supplementation on muscle function in older adults with low baseline serum 25-hydroxyvitamin D [25(OH)D].

Objectives

We aimed to test the effect of 12 mo of vitamin D supplementation on lower-extremity power and function in older community-dwelling adults screened for low serum 25(OH)D.

Methods

This was a single-center, double-blind, randomized, placebo-controlled trial that included 100 community-dwelling men and women ≥60 y old who had serum 25(OH)D ≤20 ng/mL at screening and a mean ± SD serum 25(OH)D of 20.2 ± 6.7 ng/mL at baseline. Participants were randomly assigned to 800 IU vitamin D3/d (intervention) or placebo. Those in the intervention group whose serum 25(OH)D was <28 ng/mL after 4 mo were given an additional 800 IU vitamin D3/d, whereas all other participants received placebo as an additional pill.

Results

After 12 mo, the mean ± SD serum 25(OH)D was 32.5 ± 5.1 ng/mL in the intervention group and 19.8 ± 7.3 ng/mL in the control group (treatment × time P < 0.001). The change in leg press power, function, and strength did not differ between the 2 groups over 12 mo (all treatment × time P ≥ 0.60), nor did the change in lean mass (treatment × time P ≥ 0.89).

Conclusion

Increasing serum 25(OH)D to >32 ng/mL (on average) over 12 mo did not affect lower-extremity power, strength, or lean mass in older community-dwelling adults. This trial was registered at clinicaltrials.gov as NCT02293187.

Potential Cellular and Biochemical Mechanisms of Exercise and Physical Activity on the Ageing Process

Exercise in young adults has been consistently shown to improve various aspects of physiological and psychological health but we are now realising the potential benefits of exercise with advancing age. Specifically, exercise improves cardiovascular, musculoskeletal, and metabolic health through reductions in oxidative stress, chronic low-grade inflammation and modulating cellular processes within a variety of tissues. In this this chapter we will discuss the effects of acute and chronic exercise on these processes and conditions in an ageing population, and how physical activity affects our vasculature, skeletal muscle function, our immune system, and cardiometabolic risk in older adults.

Vitamin D Receptor in Muscle Atrophy of Elderly Patients: A Key Element of Osteoporosis-Sarcopenia Connection

In this study, we investigated the relationship between sarcopenia (evaluated in term of fibers atrophy), vitamin d receptor protein expression and TaqI/Cdx2/FokI VDR genotypes in an Italian cohort of osteoporosis(n=44) and osteoarthritis (n=55) patients. Muscle biopsies were fixed and investigated by both immunohistochemistry (vitamin d receptor expression) and transmission electron microscopy (satellite stem cells niches). Vitamin d receptor polymorphisms were studied on DNA extracted from muscle paraffin sections. For the first time, we reported that aging differently affects the VDR activation in OA and OP patients. In particular, while in OP patients we observed a significant reduction of VDR positive myonuclei with age, no “age effect” was observed in OA patients. The frequent activation of VDR could explain the lower number of atrophic fiber that we observed in OA patients respect to OP. From genetic point of view, we showed a putative association among polymorphisms FokI and Cdx2 of VDR gene, vitamin d receptor activation and the occurrence of sarcopenia. Altogether these data open new prospective for the prevention and cure of age-related muscle disorders.

Association between 25-Hydroxyvitamin D Status and Components of Body Composition and Glucose Metabolism in Older Men and Women

Obesity and sarcopenia are major causes of morbidity and mortality among seniors. Vitamin D deficiency is very common especially among seniors and has been associated with both muscle health and obesity. This study investigated if 25-hydroxyvitamin D (25(OH)D) status is associated with body composition and insulin resistance using baseline data of a completed RCT among relatively healthy community-dwelling seniors (271 seniors age 60+ years undergoing elective surgery for unilateral total knee replacement due to osteoarthritis). Cross-sectional analysis compared appendicular lean mass index (ALMI: lean mass kg/height m²) and fat mass index (FMI: fat mass kg/height m²) assessed by DXA and insulin resistance between quartiles of serum 25(OH)D concentration using multivariable linear regression adjusted for age, sex, smoking status, physical activity, and body mass index (BMI). Participants in the lowest serum 25(OH)D quartile (4.7–17.5 ng/mL) had a higher fat mass (9.3 kg/m²) compared with participants in the third (8.40 kg/m²; Q3 = 26.1–34.8 ng/mL) and highest (8.37 kg/m²; Q4 = 34.9–62.5 ng/mL) quartile (p_overall = 0.03). Higher serum 25(OH)D quartile status was associated with higher insulin sensitivity (p_overall = 0.03) and better beta cell function (p = 0.004). Prevalence of insulin resistance tended to be higher in the second compared with the highest serum 25(OH)D quartile (14.6% vs. 4.8%, p = 0.06). Our findings suggest that lower serum 25(OH)D status may be associated with greater fat mass and impaired glucose metabolism, independent of BMI and other risk factors for diabetes.

Vitamin D status and its management for achieving optimal health benefits in the elderly

INTRODUCTION

Vitamin D deficiency is common, world-wide, but vitamin D repletion throughout life, and into older age, has accepted health benefits for bone. Many mechanisms through which vitamin D also benefits soft tissues are understood, and clinical evidence of such benefits is now accumulating, especially following re-analyses of trial data, which are revealing previously missed health benefits with correction of deficiency.

AREAS COVERED

The sources of vitamin D, its activation, mechanistic effects; problems of trials of supplementation for reducing health risks, the benefits shown for mortality, cardiovascular disease, infection and cancer; the global problem of vitamin D deficiency; age-related reductions in vitamin D efficacy, and currently recommended intakes.

EXPERT COMMENTARY

High prevalence of vitamin D deficiency and insufficiency worldwide have proven ill-effects on health. Governmental efforts to improve population repletion by recommending minimal daily intakes does benefit some but is not effective at the population-level. However, food fortification with vitamin D3, already implemented in some countries, can solve this highly avoidable problem cost-effectively and is probably the best way to abolish vitamin D inadequacy, allowing public health benefits to emerge over time, thereby allowing future research on vitamin D to be directed at emerging issues on vitamin D.

Calcitriol treatment in patients with low vitamin D levels

The aim of the the study is to compare the effects of cholecalciferol and calcitriol on bone mineral metabolism in women with vitamin D deficiency. Calcitriol was associated with a significant increase in bone mineral density at the lumbar spine in patients with low vitamin D levels.

PURPOSE/INTRODUCTION

Active vitamin D analogs may have larger impact in decreasing bone loss and fracture rate compared to cholecalciferol in osteoporosis. However, their effects in the treatment of vitamin D deficiency compared to cholecalciferol are not clear. The aim of the present study is to compare the effects of cholecalciferol and calcitriol on bone mineral metabolism and bone mineral density in pre- and postmenopausal women with vitamin D deficiency.

METHODS

This was a 6-month prospective, open-label, controlled clinical trial. Eligible 120 participants were pre- and postmenopausal women diagnosed with vitamin D deficiency. Forty-three subjects (group 1) received 1000 IU of cholecalciferol and 1 g of calcium daily. The other 77 subjects (group 2) received 0.5 μg calcitriol in addition to 400 IU of cholecalciferol and 1 g of calcium daily.

RESULTS

Oral vitamin D supplementation did not increase bone mineral density after 6 months of intervention in group 1. On the other hand, bone mineral density at the lumbar spine increased from 0.809 ± 0.172 to 0.848 ± 0.161 g/cm² in group 2 patients (p < 0.017 vs baseline).

CONCLUSIONS

Oral daily calcitriol was associated with a significant increase in bone mineral density at the lumbar spine in patients with low vitamin D, elevated PTH, and osteoporosis.

Can vitamin D deficiency influence muscle performance in postmenopausal women? A multicenter retrospective study

BACKGROUND

The presence of the vitamin D receptor (VDR) has been recently demonstrated in human muscle supporting the theory of a role of vitamin D in the proliferation and differentiation of muscle cells. So far only few studies investigated the association between vitamin D and muscle performance in postmenopausal women.

AIM

To define the functional impact of vitamin D deficiency.

DESIGN

Multicenter retrospective study.

SETTING

Five Italian outpatient services of Physical and Rehabilitation Medicine (PRM).

POPULATION

Postmenopausal women.

METHODS

We divided the population in two groups based on the threshold of 30 ng/mL as cut-off to define sufficient and insufficient serum levels of 25-hydroxyvitamin D3 [25(OH)D3]. Outcome measures were: appendicular lean mass (ALM); ALM-to-BMI ratio (ALMBMI); total fat mass (FM); visceral adipose tissue (VAT); Hand Grip Strength (HGS); Knee Isometric Extension Strength (KES); Short Physical Performance Battery (SPPB); 4-meter gait speed (4MGS).

RESULTS

We analyzed the data records of 401 postmenopausal women (mean age 66.93±8.47 years): 203 with hypovitaminosis D (mean age 66.81±8.11 years) and 198 with normal levels of 25(OH)D3 (mean age 67.04±8.84 years). The analysis showed a significant difference between the two groups in terms of: ALMBMI (0.002), FM (P<0.001), VAT mass (0.010), VAT volume (P=0.006), HGS (P<0.001), KES (P<0.001), SPPB score (P<0.001), percentage of people with a 4MGS≤0.8 m/s (P<0.001). Furthermore, there were significant correlations (P<0.001) between serum levels of 25(OH)D3 and HGS (r=0.323), KES (r=0.510), and SPPB sit to stand (r=-0.362) and walking sub-scores (r=-0.312).

CONCLUSIONS

This multicenter study demonstrated that postmenopausal women with vitamin D deficiency had a significant reduction of appendicular muscle strength and physical performance.

CLINICAL REHABILITATION IMPACT

This study reported the frequency of hypovitaminosis D in postmenopausal women and its influence on the reduction of muscle mass, strength, and physical performance in a typical population referring to the physiatrist for musculoskeletal disorders.

Vitamin D Status and Vitamin D Receptor Gene Polymorphisms Are Associated with Pelvic Floor Disorders in Women

Objectives

To investigate if vitamin D receptor (VDR) gene polymorphisms and circulating vitamin D levels are associated with pelvic floor disorders (PFDs).

Methods

In this case-control study, 25-hydroxy-vitamin D (25[OH]D) serum levels were analyzed in 47 females with PFDs and 87 healthy females (controls), respectively. The VDR gene polymorphisms were determined by using polymerase chain reaction and performing digestions with 4 restriction enzymes i.e., ApaI, TaqI, FokI, and BsmI. Vitamin D levels of patients were divided into <20 ng/mL, 20 to 30 ng/mL, and ≥30 ng/mL categories.

Results

Our correlative analysis of VDR polymorphisms as a function of the presence of PFD showed that ApaI and BsmI polymorphisms were significantly associated with PFD in vitamin-D-deficiency and insufficiency groups (P < 0.05). Mean vitamin D levels did not differ between the PFD case (13.01 ± 0.84 ng/mL) and control (15.11 ± 1.04 ng/mL) groups (P > 0.05). However, there was a significant difference in the distribution of vitamin D levels between study group and controls using Pearson's χ² test (<20 ng/mL, 20–30 ng/mL, and >30 ng/mL: 87.2%, 12.8%, and 0% in the study group and 75.9%, 16.1%, and 8.0% in controls, respectively, P < 0.05). Taken together, our observations suggest that vitamin D levels could be associated with PFDs and that 2 polymorphisms (i.e., ApaI and BsmI) in the VDR gene may contribute to an increased prevalence of PFDs in women with insufficient levels of vitamin D.

Conclusions

Examining vitamin D levels and performing a VDR genotype analysis may be helpful for assessing PFD risk.

The Effect of Nordic Walking Training Combined with Vitamin D Supplementation on Postural Control and Muscle Strength in Elderly People-A Randomized Controlled Trial

Nordic Walking (NW) and Vitamin D concentration (Vit D) alone have been shown to contribute to the health and performance of elderly people. However, the interaction between these two factors has yet to be explored. In this study 42 women over 60 years of age (69.02 ± 5.56 years) were recruited and divided in two NW groups: a high-intensity interval training group (HI-NW) and a moderate-intensity continuous training group (MI-NW). Individuals from each group completed a 12-week NW training program (3 times a week/2 hours) combined with randomized Vitamin D supplementation (HD = high dose: 4000 IU/day or LD = low dose: 800 IU/day). Body composition, postural control, muscle strength and Vitamin D serum concentration were measured twice; before and after the intervention. To investigate the interaction between supplementation and training a mixed-design analysis of variance (ANOVA) was performed. The HI-NW group, regardless of supplementation dose, increased their Vit D and elbow torque performance. On the other hand, in the MI-NW group the same Vit D outcome was seen only with HD supplementation and was also associated with increased leg muscle mass. In conclusion, beneficial effects of both HI-NW and MI-NW training regimes were seen. The impact of the dose supplementation on Vit D and body composition was related to the type of NW training.

Recovery after unilateral knee replacement due to severe osteoarthritis and progression in the contralateral knee: a randomised clinical trial comparing daily 2000 IU versus 800 IU vitamin D

Objective

To test whether daily high-dose vitamin D improves recovery after unilateral total knee replacement.

Methods

Data come from a 24-month randomised, double-blind clinical trial. Adults aged 60 and older undergoing unilateral joint replacement due to severe knee osteoarthritis were 6-8 weeks after surgery randomly assigned to receive daily high-dose (2000 IU) or standard-dose (800 IU) vitamin D₃. The primary endpoints were symptoms (Western Ontario and McMaster Universities Arthritis Index pain and function scores) assessed at baseline, 6, 12, 18 and 24 months in both knees, and the rate of falls over 24 months. The secondary outcomes were sit-to-stand performance, gait speed, physical activity and radiographic progression in the contralateral knee.

Results

We recruited 273 participants, 137 were randomised to receive 2000 IU and 136 were randomised to receive 800 IU vitamin D per day. 2000 IU vitamin D increased 25-hydroxyvitamin D levels to 45.6 ng/mL and 800 IU vitamin D to 37.1 ng/mL at month 24 (p<0.0001). While symptoms improved significantly in the operated knee and remained stable in the contralateral knee over time, none of the primary or secondary endpoints differed by treatment group over time. The rate of falls over 24 months was 1.05 with 2000 IU and 1.07 with 800 IU (p=0.84). 30.5% of participants in the 2000 IU and 31.3% of participants in the 800 IU group had radiographic progression in the contralateral knee over 24 months (p=0.88).

Conclusions

Our findings suggest that a 24-month treatment with daily 2000 IU vitamin D did not show greater benefits or harm than a daily standard dose of 800 IU among older adults undergoing unilateral total knee replacement.

The combination of vitamin D deficiency and overweight affects muscle mass and function in older post-menopausal women

BACKGROUND

It has been suggested that overweight and obese individuals have an increased risk to develop vitamin D deficiency, commonly associated with poor muscle performance. The relationship among fat mass, vitamin D status, and skeletal muscle is still debated.

AIMS

To evaluate the effects of the combination of hypovitaminosis D and overweight on muscle mass and strength, and physical performance in post-menopausal women.

METHODS

In this cross-sectional study, we recruited post-menopausal women referring to a physiatric outpatient service for the management of osteoporosis over a 36-month period. We compared four groups: (1) normal weight with hypovitaminosis D; (2) overweight with normal serum 25(OH)D3; (3) overweight with hypovitaminosis D; and (4) normal weight with normal serum 25(OH)D3 (control group). Outcome measures were: appendicular lean mass-to-BMI ratio; hand grip strength; and short physical performance battery.

RESULTS

We analysed 368 women (mean aged 67.2 ± 7.8 years): 95 normal weight with hypovitaminosis D, 90 overweight with normal levels of 25(OH)D3, 96 overweight with hypovitaminosis D, and 87 normal weight with normal levels of 25(OH)D3. Overweight women with hypovitaminosis D had a significant risk of reduced muscle mass (OR 5.70; p < 0.001), strength (OR 12.05; p < 0.001), and performance (OR 5.84; p < 0.001) compared to controls. Normal weight women with hypovitaminosis D had only a greater risk of an impairment of muscle strength (OR 7.30; p < 0.001) and performance (OR 3.16; p < 0.001).

DISCUSSION

According to our findings, both hypovitaminosis D and overweight should be investigated in post-menopausal women because of their negative effects on skeletal muscle mass and function.

CONCLUSIONS

This study demonstrated that hypovitaminosis D is associated to impaired muscle function and its combination with overweight might lead also to muscle wasting in a cohort of post-menopausal women.

Vitamin D and muscle

Vitamin D is increasingly recognised to play an important role in normal muscle function. Low vitamin D status is associated with an increased risk of falls and proximal weakness. Since vitamin D deficiency is very common, and the signs are non-specific, it is important to maintain a high index of suspicion of vitamin D deficiency in patients with muscle pain and weakness, and it is simple to measure serum 25(OH) vitamin D. Therapy is cheap, safe and effective, but sometimes a larger dose may be needed, and, as shown in our case report, willingness of people to pay for an over the counter medication can be an issue. Following a striking case report that demonstrates muscle defects in severe vitamin D deficiency, we discuss clinical studies examining specific effects of vitamin D on physical performance, muscle strength and falls. Finally, we present an overview of molecular mechanisms that explain vitamin D's biological effects on muscle.

•

Low vitamin D is associated with an increased risk of falls and proximal weakness.

•

Therapy is cheap, safe and effective, but larger doses may be needed and willingness to pay for over the counter medications can be an issue.

•

We present an overview of molecular mechanisms that explain vitamin D’s biological effects on muscle.

Prevalence of vitamin D insufficiency and evidence for disease prevention in the older population

The prevalence of vitamin D insufficiency, usually assessed by the analysis of circulating 25-hydroxyvitamin D (25[OH])D), is very high in the aging German population. An important factor that reduces endogenous vitamin D synthesis in older persons is physical inactivity or care-dependency that limits the time spent outside. Additionally, it has been suggested that the age-dependent decline in the glomerular filtration rate is associated with a reduced production of bioactive calcitriol. As this phenomenon is not detectable by the assessment of 25(OH)D, it is necessary to analyze the level of parathyroid hormone as a marker of calcitriol function. Because 25(OH)D levels are highly correlated with an active and healthy life style, data from epidemiological studies are not necessarily suitable to elucidate the role of vitamin D in disease prevention. Recently published meta-analyses of randomized controlled trials (RCTs) showed moderate effects of vitamin D supplementation on fracture risk and found that vitamin D was more effective when administered in combination with calcium. The role of vitamin D in the prevention of falls and frailty remains unclear. Much evidence has demonstrated the beneficial effects of vitamin D on respiratory tract infections and asthma, which are very relevant health issues in the older population. To conclude, vitamin D, particularly combined with calcium, has moderately beneficial effects on the skeletal system and is useful for the prevention of respiratory tract infections.

Evaluating Vitamin D Status in Pre- and Postmenopausal Type 2 Diabetics and Its Association with Glucose Homeostasis

Background

Type 2 Diabetes Mellitus (T2DM) and menopause are associated with vitamin D status. Oestrogen decline during menopausal stages promotes hypovitaminosis D. However, the interplay between vitamin D, menopause, lifestyle, and T2DM cannot be overlooked. This study assessed vitamin D status among pre- and postmenopausal T2DM women and determined its association with glycemic control and influence of lifestyle habits on hypovitaminosis D.

Methods

This cross-sectional study was conducted at the Komfo Anokye Teaching Hospital, Kumasi, Ghana. Structured questionnaires were administered to 192 T2DM women; blood samples were collected for estimation of 25(OH) D and insulin using ELISA. Fasting blood glucose (FBG), lipid profile, glycated haemoglobin (HbA1c), and calcium were measured. Statistical analyses were performed using Graphpad Prism 6.

Results

The prevalence of vitamin D inadequacy was 92.2%. Hypovitaminosis D was more prevalent among the postmenopausal T2DM women (63.8% versus 58.2%). Hypovitaminosis D significantly associated with insulin [R² = 0.01760, p = 0.0008], HbA1c [R² = 0.3709, p = <0.0001], and FBG [R² = 0.3465, p = 0.0001] in only the postmenopausal women.

Conclusion

Vitamin D deficiency is prevalent in pre- and postmenopausal T2DM but higher among postmenopausal women. Adequate vitamin D levels in both groups were associated with improved glucose control while hypovitaminosis D in the postmenopausal women was related to poorer glucose control. Vitamin D screening should be incorporated into management plan for T2DM to serve as an early tool for prevention of vitamin D deficiency.

Effects of Nordic Walking on Oxidant and Antioxidant Status: Levels of Calcidiol and Proinflammatory Cytokines in Middle-Aged Women

Objectives

Nordic walking (NW) is relatively new and popular type of physical exercise with less studied effects than other sports activities. The aim of the study was to analyze possible changes in somatic indices, oxidant and antioxidant status, interleukins, and calcidiol levels in middle-aged women after a 12-week NW training program.

Study Design

In this study, we examined the effects of NW training on selected measures and changes in body weight, fat mass, and calcidiol levels.

Methods

The study group consisted of 13 women (46 ± 4.2 years), who took part in trainings. Before and after the training program, some anthropometric indices were determined and selected biochemical parameters were measured in blood.

Results

NW training led to a significant decrease of the total body mass and fat mass and to an increase in lean body mass (p < 0.05). It also contributed to a significant increase in total antioxidative status (TAS) and calcidiol levels (p < 0.05). Before training, a reverse correlation between IL-6 and total oxidative capacity (TOC) levels (p < 0.05) was found, while after training between IL-6 and calcidiol levels (p ≤ 0.001).

Conclusions

12-week NW training undertaken by premenopausal women not only has a positive effect on body composition but also on the plasma antioxidative capacity.

Weather conditions and their effect on seasonality of incident osteoporotic hip fracture

Our aim was to analyze the seasonality and the effect of weather conditions on the incidence of osteoporotic hip fracture in a Southern European region.

INTRODUCTION

The objective of this work is to evaluate seasonality and the effect of weather conditions on the incidence of osteoporotic hip fracture in a Southern European region.

METHODS

This retrospective cohort study included all patients admitted to Alcorcón Foundation University Hospital with a diagnosis of osteoporotic hip fracture between the years 1999 and 2015. In a time series analysis, we examined the association between hip fracture incidence and different weather conditions and seasonality using general additive models (with Poisson distribution). The incidence rate ratio (IRR) crude and adjusted by season was estimated for all parameters. Hip incidence was further analyzed by sex and age (below or over 75) subgroups.

RESULTS

Four thousand two hundred seventy-one patients with an osteoporotic hip fracture were included (79% females, mean age 83.8). Season fracture rate was significantly higher in fall and winter (67.06 and 64.41 fractures/season) compared to summer and spring (59.71 and 60.06; p < 0,001). Hip fracture incidence was 15% greater in autumn and winter than in spring and summer. Fog [IRR 1.15 (95% CI: 1.003-1.33)], atmospheric pressure (per 100 mb) [IRR 1.05 (95% CI: 1.004-1.114)], and frost [IRR 1.15 (95% CI: 1.03-1.30)] were significantly associated with increased hip fracture. Haze [IRR 1.10 (95% CI: 0.99-1.23)] showed a trend without statistical significance. Daily average temperature (per 5 °C) [IRR 0.98 (95% CI: 0.957-0.996)], rain (per 10 ml) [IRR 0.99 (95% CI: 0.981-1.0)], wind speed [IRR = 0.952, (95% CI: 0.907-0.998)], and daily ultraviolet radiation (per 100 joules) [IRR 0.998 (95% CI: 0.996-1.0)] were negatively associated with fracture. After adjusting by season and trend, all these associations disappear.

CONCLUSIONS

In this Southern region, hip fracture incidence exhibits a seasonal pattern different from those communicated in Northern regions. There is short-term association with different weather conditions that partly explain this seasonal pattern.

The vitamin D receptor expression in skeletal muscle of women with distal radius fracture

We evaluated the vitamin D receptor (VDR) expression in the forearm flexor muscle of women with distal radius fracture. High VDR expression was associated with low appendicular lean mass index.

INTRODUCTION

We aimed to evaluate the relationship between the VDR expression in the muscle cell and the muscle mass in women with a distal radius fracture (DRF).

METHODS

We prospectively recruited 45 women over 50 years of age (mean age, 66 years) with DRF and acquired biopsy of the forearm flexor muscle. The muscle cross-sectional area (CSA) and VDR expression were measured using immunohistochemistry staining. The clinical parameters including grip strength, gait speed, body mass index (BMI), bone mineral density (BMD), and serum vitamin D levels were compared between patients grouped by appendicular lean mass index and were correlated with the VDR expression.

RESULTS

Twelve patients (27%) showed a decreased appendicular lean mass index, less than the cut-off value of 5.4 kg/m2 which was suggested by the Asian Working Group for Sarcopenia. Patients with a low appendicular lean mass index had significantly lower muscle CSA (p = 0.037), but a higher VDR expression (p = 0.045) than those with higher indices. VDR expression was negatively correlated with BMI (r = - 0.417, p = 0.004) and appendicular lean mass index (r = - 0.316, p = 0.044).

CONCLUSIONS

DRF patients with low appendicular lean mass index presented high VDR expression and low CSA in forearm muscle cells. This suggests that the VDR expression might be upregulated in the attempt to compensate for the decreasing muscle mass. Further studies are necessary to explore the role of VDR in the progression of sarcopenia.

Expression of vitamin D receptor in the subsynovial connective tissue in women with carpal tunnel syndrome

Studies suggest that low vitamin D levels are associated with carpal tunnel syndrome. We aimed to evaluate whether level of vitamin D receptor expression in the endothelial cells of the subsynovial connective tissue is associated with clinical features of carpal tunnel syndrome. We obtained the subsynovial connective tissue from 52 women with carpal tunnel syndrome during surgery and performed immunohistochemical analysis of vitamin D receptors in the endothelial cells of the subsynovial connective tissue. We explored correlation of vitamin D receptor expression with clinical features of carpal tunnel syndrome, such as age, symptom duration, symptom severity and electrophysiological severity. Diverse range of vitamin D receptor expression was observed. Vitamin D receptor expression was independently associated with distal motor latency. This suggests that vitamin D receptor expression may be associated with disease progression, as prolonged distal motor latency reflects severity of the disease. Further studies are necessary to explore the role of vitamin D and vitamin D receptors in patients with carpal tunnel syndrome.

LEVEL OF EVIDENCE

IV.

A role for nutritional intervention in addressing the aging neuromuscular junction

The purpose of this review is to discuss the structural and physiological changes that underlie age-related neuromuscular dysfunction and to summarize current evidence on the potential role of nutritional interventions on neuromuscular dysfunction-associated pathways. Age-related neuromuscular deficits are known to coincide with distinct changes in the central and peripheral nervous system, in the neuromuscular system, and systemically. Although many features contribute to the age-related decline in neuromuscular function, a comprehensive understanding of their integration and temporal relationship is needed. Nonetheless, many nutrients and ingredients show promise in modulating neuromuscular output by counteracting the age-related changes that coincide with neuromuscular dysfunction. In particular, dietary supplements, such as vitamin D, omega-3 fatty acids, β-hydroxy-β-methylbutyrate, creatine, and dietary phospholipids, demonstrate potential in ameliorating age-related neuromuscular dysfunction. However, current evidence seldom directly assesses neuromuscular outcomes and is not always in the context of aging. Additional clinical research studies are needed to confirm the benefits of dietary supplements on neuromuscular function, as well as to define the appropriate population, dosage, and duration for intervention.

Vitamin D and rheumatoid arthritis: an ongoing mystery

PURPOSE OF REVIEW

In recent years, there has been a growing interest in the value of vitamin D and its effects on autoimmunity. The aim of this review is to summarize the current knowledge on the association between vitamin D and rheumatoid arthritis (RA) in terms of prevalence, disease activity, clinical expression, serology and gene polymorphisms of vitamin D receptors.

RECENT FINDINGS

Studies have shown contrasting findings concerning the association between vitamin D levels and RA. Vitamin D seems to have immunomodulatory properties. Therefore, low vitamin D levels could contribute to increased immune activation. However, the potential role of vitamin D supplementation in preventing RA manifestation and its beneficial role as a component of RA treatment remain controversial. The relationship between RA susceptibility and vitamin D polymorphisms is also unclear.

SUMMARY

Despite advancements synthesized by some recent meta-analyses, the relationship between vitamin D and RA requires further evaluation. Further research is needed to confirm the relationship between RA susceptibility and vitamin D polymorphisms and to determine whether vitamin D plays a role in preventing the manifestation of RA. Finally, additional studies are required to determine the impact and optimal amount of vitamin D supplementation in the treatment of RA patients.

Skeletal muscle performance and ageing

The world population is ageing rapidly. As society ages, the incidence of physical limitations is dramatically increasing, which reduces the quality of life and increases healthcare expenditures. In western society, ~30% of the population over 55 years is confronted with moderate or severe physical limitations. These physical limitations increase the risk of falls, institutionalization, co-morbidity, and premature death. An important cause of physical limitations is the age-related loss of skeletal muscle mass, also referred to as sarcopenia. Emerging evidence, however, clearly shows that the decline in skeletal muscle mass is not the sole contributor to the decline in physical performance. For instance, the loss of muscle strength is also a strong contributor to reduced physical performance in the elderly. In addition, there is ample data to suggest that motor coordination, excitation-contraction coupling, skeletal integrity, and other factors related to the nervous, muscular, and skeletal systems are critically important for physical performance in the elderly. To better understand the loss of skeletal muscle performance with ageing, we aim to provide a broad overview on the underlying mechanisms associated with elderly skeletal muscle performance. We start with a system level discussion and continue with a discussion on the influence of lifestyle, biological, and psychosocial factors on elderly skeletal muscle performance. Developing a broad understanding of the many factors affecting elderly skeletal muscle performance has major implications for scientists, clinicians, and health professionals who are developing therapeutic interventions aiming to enhance muscle function and/or prevent mobility and physical limitations and, as such, support healthy ageing.

Vitamin D and Ageing

One hundred years has passed since the discovery of vitamin D as the active component of cod-liver oil which cured the bone disease rickets. Since then our knowledge of vitamin D has expanded tremendously and has included recognition of the importance of UV radiation as a source of the vitamin as well as the discovery of the vitamin as a nutrient, a pro-hormone and a potent steroid hormone with a major role in calcium and bone metabolism. In the last 25 years or so, the discovery of the vitamin D receptor in over 30 different body tissues together with the existence of the alpha-1-hydroxylase enzyme in these tissues provided evidence of a pleiotropic role of vitamin D outside its classical role in the skeleton. These important discoveries have provided the basis for the increasing interest in vitamin D in the context of nutritional requirements for health including the prevention of chronic diseases of ageing. The recent publication of the Dietary Reference Intake report on vitamin D and calcium by the North American Institute of Medicine (IOM) is the most comprehensive report to date on the basis for setting nutritional requirements for vitamin D. This chapter will summarize the nutritional aspects of vitamin D and discuss the changes in vitamin D metabolism and requirements with ageing. It will summarize key evidence on the relationship between vitamin D status and some of the main ageing related health outcomes including bone, muscle and cognitive health as well as survival focusing on the published literature in very-old adults (those >= 85 years of age).