Prevalence of clinically relevant muscle weakness and its association with vitamin D status among older adults in Ecuador

Arm muscle area is correlated to handgrip strength in postmenopausal women

OBJECTIVE

To analyze the correlation between arm muscle area and handgrip strength among postmenopausal community dwelling low-income women in order to provide an easy anthropometric indicator to assess muscle mass quantity and quality.

METHODS

This was a cross-sectional study involving postmenopausal women (n = 171) from three urban-marginal communities of Guayaquil, Ecuador. Corrected arm muscle area was calculated using the Frisancho formula. Dynapenia was defined as HGS < 16 kg. Spearman's correlation coefficient was calculated at a 5% significance level to test the correlation between corrected arm muscle area and handgrip strength.

RESULTS

Median (interquartile range: IQR) age of the sample was 72.0 years (17.0). The median of corrected arm muscle area was 34.8 cm2 (20.7). The overall prevalence of dynapenia was 57.9% (n = 99). There was a significant decreasing trend with age regarding all anthropometric characteristics and handgrip strength, as well as a higher prevalence of dynapenia with age. For the whole sample, a statistically significant positive correlation was found between corrected arm muscle area and handgrip strength [r = 0.267; p < .001].

There was a significant yet weak positive correlation between corrected arm muscle area and handgrip strength in this postmenopausal sample. There is a need for additional research in this regard.

Sex-dependent association of serum vitamin D with muscle strength in older adults: NHANES 2001-2002

BACKGROUND

Although several studies have suggested a potential positive association between serum vitamin D levels and muscle strength in older adults, it remains unclear whether this relationship is sex-dependent.

AIM

To evaluate the association between serum 25 hydroxyvitamin D [25(OH)D] levels and muscle strength in older adults and to assess whether this association is dependent on sex.

METHODS

This cross-sectional study utilized data from the National Health and Nutrition Examination Survey (NHANES) conducted between 2001 and 2002. A total of 1173 individuals aged 50-85 years (630 men and 543 women) were included in the analysis. The peak isokinetic force of the knee extensor was assessed using a kinetic communicator isokinetic dynamometer. Serum 25(OH)D levels were measured using the standardized liquid chromatography-tandem mass spectrometry method. Linear regression analyses were conducted to estimate coefficients and 95% confidence intervals for muscle strength across tertiles of serum vitamin D levels, adjusting for potential confounders.

RESULTS

Tertiles of serum vitamin D were positively associated with muscle strength in older men (p-trend = 0.007), whereas no association was observed in older women (p-trend = 0.140) or in the total sample (men and women together; p-trend = 0.139).

CONCLUSION

Serum vitamin D levels were positively associated with muscle strength specifically in older men, whereas no association was observed in older women. These results suggest that the relationship between vitamin D and strength may be sex-dependent.

Association between dynapenic obesity phenotypes and physical performance in middle-age and older women living in community

Background

Dynapenic obesity (DO) is the coexistence of excess adipose tissue/body weight and low muscle strength. This condition is associated with an increased risk of suffering from various chronic diseases and physical deterioration in older people.

Aim

To analyze the association between DO phenotypes and physical performance in middle-aged women living in the community.

Methods

This cross-sectional study was conducted on middle-aged and older women (≥50 years) residing in Guayaquil, Ecuador. Dynapenia was diagnosticated by a handgrip strength (HGS) < 16 kg; obesity was determined based on body mass index (BMI) ≥ 30 kg/m2. Participants were categorized into four groups based on their dynapenia and obesity status: non-dynapenic/non-obesity (ND/NO), obesity/non-dynapenic (O/ND), dynapenic/non-obesity (D/NO) and dynapenic/obesity (D/O). Physical performance was assessed by the Short Physical Performance Battery (SPPB).

Results

A total of 171 women were assessed. The median (IQR) age of the sample was 72.0 (17.0) years. Obesity and dynapenia were 35% (n = 60) and 57.8% (n = 99) of the participants, respectively. The prevalence of ND/NO was 25.1% (n = 43), O/ND 17% (n = 29), D/NO 39.8% (n = 68) and DO 18.1% (n = 31). The mean SPPB total score was 6.5 ± 3.2. Participants of D/NO and DO groups presented significantly lower mean SPPB scores (p < 0.001) compared to those of NO/ND and O/ND groups.

Conclusion

Women with DO and D/NO exhibited significantly lower SPPB scores, indicating poorer physical performance. These findings emphasize the importance of incorporating a comprehensive assessment of muscle strength and obesity in middle-aged and older women.

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.

Are Serum 25-Hydroxyvitamin D Deficiency and Insufficiency Risk Factors for the Incidence of Dynapenia?

Epidemiological evidence showing the association between low 25(OH)D and age-related reduction in neuromuscular strength (dynapenia) is a paucity and controversial and, to date, the effect of osteoporosis and vitamin D supplementation on these associations has not been measured. Thus, we analyze whether serum 25(OH)D deficiency and insufficiency are risk factors for the incidence of dynapenia in individuals aged 50 or older and whether osteoporosis or vitamin D supplementation modify these associations. For that, 3205 participants of the ELSA study who were non-dynapenic at baseline were followed for 4 years. Vitamin D was measured at baseline by the serum concentration of 25(OH)D and classified as sufficient (&gt; 50 nmol/L), insufficient (≥ 30 and ≤ 50 nmol/L) or deficient (&lt; 30 nmol/L). The incidence of dynapenia was determined by a grip strength &lt; 26 kg for men and &lt; 16 kg for women at the end of the 4-year follow-up. Poisson regression models were adjusted by sociodemographic, behavioral, clinical and biochemical characteristics. Serum 25(OH)D deficient was a risk factor for the incidence of dynapenia (IRR = 1.70; 95% CI 1.04-2.79). When only individuals without osteoporosis and those who did not use vitamin D supplementation were analyzed, both serum 25(OH)D deficiency (IRR = 1.78; 95% CI 1.01-3.13) and insufficiency (IRR = 1.77; 95% CI 1.06-2.94) were risk factors for the incidence of dynapenia. In conclusion, a serum level of 25(OH)D &lt; 30 nmol/L is a risk factor for the incidence of dynapenia. Among individuals without osteoporosis and those who do not take vitamin D supplementation, the threshold of risk is higher (≤ 50 nmol/L).

Cross sectional determinants of VO2 max in free living Iranians: Potential role of metabolic syndrome components and vitamin D status

BACKGROUND AND AIMS

The purpose of the study was to evaluate the determinants of cardiorespiratory fitness (CRF) in Iranian adults and the potential contribution of vitamin D status.

METHODS

In this cross-sectional study 264 cases (116 men and 147 women aged 18-70 years old were participated. Maximal oxygen consumption (VO_{2 max}) was measured by the Bruce protocol utilizing treadmill exercise testing. Anthropometric data, body composition and fasting blood glucose and lipid concentrations were measured. Serum levels of 25-hydroxyvitamin D (25(OH)D) and 1,25-dihydroxyvitamin D (1,25(OH)₂D) were assessed using enzyme-linked immunosorbent assay. Stepwise linear regression analysis was applied to determine significant predictors of VO2 peak. We tested non-linear (quadratic and cubic terms) versus linear association of adjusted (for determinants) VO2 max and vitamin D levels.

RESULTS

Multiple regression results showed that fat free mass, HDL-C and physical activity, waist circumference, age and sex were determinants of VO_{2 peak}. All of these explained the 65.3% of VO2 peak. There was a non-linear cubic association (R² = 0.03, p = 0.046) between serum 25(OH)D and adjusted VO2 peak in which 25(OH)D in people with a high 25(OH)D levels (>60 nmol/L), had better fitness and those with serum 25(OH) less than 20 nmol/L. We found no linear and non-linear associations between serum 1,25(OH)₂ D and adjusted VO_{2 max}.

CONCLUSIONS

Our results showed that waist circumference and HDL-C, as components of metabolic syndrome, contribute ∼2% to the variance in VO_{2 max}. Moreover, high concentrations of 25(OH)D but not 1,25(OH)₂ D may make additional contributions to CRF.

The Vitamin D/Vitamin D receptor (VDR) axis in muscle atrophy and sarcopenia

Muscle atrophy and sarcopenia (the term given to the age-related decline in muscle mass and function), influence an individuals risk of falls, frailty, functional decline, and, ultimately, impaired quality of life. Vitamin D deficiency (low serum levels of 25-hydroxyvitamin D (25(OH)D₃)) has been reported to impair muscle strength and increase risk of sarcopenia. The mechanisms that underpin the link between low 25(OH)D₃ and sarcopenia are yet to be fully understood but several lines of evidence have highlighted the importance of both genomic and non-genomic effects of active vitamin D (1,25-dihydroxyvitamin D (1,25(OH)₂D₃)) and its nuclear vitamin D receptor (VDR), in skeletal muscle functioning. Studies in vitro have demonstrated a key role for the vitamin D/VDR axis in regulating biological processes central to sarcopenic muscle atrophy, such as proteolysis, mitochondrial function, cellular senescence, and adiposity. The aim of this review is to provide a mechanistic overview of the proposed mechanisms for the vitamin D/VDR axis in sarcopenic muscle atrophy.

Association of Vitamin D Supplementation in Cardiorespiratory Fitness and Muscle Strength in Adult Twins: A Randomized Controlled Trial

Although vitamin D is related to cardiorespiratory fitness and muscle strength, there is no evidence in the literature about the genetic influence of the response to vitamin D supplementation and improvements in these parameters. Therefore, we evaluate the effect of longitudinal supplementation of vitamin D on parameters of physical fitness in monozygotic twins. In total, 74 participants were included, with a mean age of 25 years, divided into two groups, one group received supplementation with cholecalciferol for 60 days and the other group did not. Cardiorespiratory fitness and muscle strength were measured before and after supplementation through maximal treadmill tests and dynamometry, respectively. Wilcoxon tests were used to compare intragroup results and the Mann-Whitney test to examine intergroup differences. There was an increase in the serum concentration of vitamin D in participants who ingested the supplementation. Cardiorespiratory fitness improved after supplementation through increases in the values of maximum oxygen consumption of 28% (p < .001). Muscle strength in left hand grip increased 18% in participants who received the supplement (p = .007). Sixty days of cholecalciferol supplementation improved cardiorespiratory fitness and upper limb muscle strength.

The Association between 25-Hydroxyvitamin D Concentration and Disability Trajectories in Very Old Adults: The Newcastle 85+ Study

Background: Low vitamin D status is common in very old adults which may have adverse consequences for muscle function, a major predictor of disability. Aims: To explore the association between 25-hydroxyvitamin D [25(OH)D] concentrations and disability trajectories in very old adults and to determine whether there is an 'adequate' 25(OH)D concentration which might protect against a faster disability trajectory. Methodology: A total of 775 participants from the Newcastle 85+ Study for who 25(OH)D concentration at baseline was available. Serum 25(OH)D concentrations of <25 nmol/L, 25-50 nmol/L and >50 nmol/L were used as cut-offs to define low, moderate and high vitamin D status, respectively. Disability was defined as difficulty in performing 17 activities of daily living, at baseline, after 18, 36 and 60 months. Results: A three-trajectory model was derived (low-to-mild, mild-to-moderate and moderate-to-severe). In partially adjusted models, participants with 25(OH)D concentrations <25 nmol/L were more likely to have moderate and severe disability trajectories, even after adjusting for sex, living in an institution, season, cognitive status, BMI and vitamin D supplement use. However, this association disappeared after further adjustment for physical activity. Conclusions: Vitamin D status does not appear to influence the trajectories of disability in very old adults.

Prevalence of motor impairment in residents of New South Wales, Australia aged 55 years and over: cross-sectional survey of the 45 and Up cohort

BACKGROUND

The population prevalence of many diseases is known. However, little is known of the population prevalence of motor impairments.

METHODS

The aim of this study was to determine the point prevalence of specific motor impairments (weakness, fatigue, contracture, impaired balance and impaired coordination) in the population aged 55 years and older resident in New South Wales, Australia in 2018. 55,210 members of the 45 and Up cohort were invited to participate in a follow-up survey that included questions on motor impairment. Responses were received from 20,141 people (36%). Calibrated estimates of prevalence of specific motor impairments, and of having at least one motor impairment, were obtained using survey weights based on the known multivariate distributions of age, gender and geographical location (28 regions) in the population.

RESULTS

More than one-third of adults aged over 55 residing in New South Wales have difficulty using their hands, arms or legs. The prevalence of each motor impairment (muscle weakness, fatigue, contracture, impaired balance or impaired coordination) in this population is between 4 and 12%. The prevalence of at least one of these impairments is 21%. The prevalence of at least one impairment in people aged 85 and over is 42%. Women consistently had more difficulty using hands, arms and legs, and more motor impairment, than men. Difficulty using hands, arms and legs and the prevalence of all motor impairments, especially poor balance, greatly increased with age.

CONCLUSION

The prevalence of specific motor impairments in older Australian adults is high - comparable to that of the most prevalent diseases. There may be merit in considering motor impairment as a significant public health problem in its own right.

Analysis of Related Factors of Brittle Hip Fracture in Postmenopausal Women with Osteoporosis

OBJECTIVE

To investigate the effects of age, body mass index (BMI), bone mineral density (BMD), and levels of serum 25-hydroxyvitamin D (25OHD) on hip fracture on the condition of the bone density of femoral neck having reached the threshold of osteoporosis.

METHODS

A total of 252 postmenopausal women patients, whose bone density had reached the threshold of osteoporosis and age ≥50 years (50-98 years), collected from the Second Affiliated Hospital of Fujian Medical University from January 2015 to December 2018, were performed by retrospective analysis. According to whether or not they had a hip fracture, including femoral neck fracture or intertrochanteric fracture, the patients were divided into two groups, including 117 cases (50-84 years old) in the non-hip fracture group and 135 cases (57-98 years old) in the hip fracture group. BMD was measured by Hologic Discovery A DXA bone mineral densitometer. Levels of serum 25OHD were detected by ROCHE detection instrument. Comparisons of age, BMI, bone density of femoral neck, and levels of serum 25OHD between the two groups were performed by using the Student's t-test. Furthermore, the statistically significant factors were analyzed by multiple regression analysis to investigate the independent risk factors of hip fracture.

RESULTS

The group without hip fracture: 117 cases; average age: 67.4 ± 8.5 years; BMI: 22.3 ± 3.2 kg/m2 ; bone density of femoral neck: (0.504 ± 0.067) g/cm2 ; T-value of femoral neck: -3.1 ± 0.6; levels of serum 25OHD: (24.9 ± 8.5) ng/mL. The group with brittle hip fracture: 135 cases; average age: 80.7 ± 7.6 years; BMI: 20.3 ± 3.5 kg/m2 ; bone density of femoral neck: (0.426 ± 0.077) g/cm2 ; T-value of femoral neck: -3.8 ± 0.7; levels of serum 25OHD: (15.9 ± 8.9) ng/mL. Age, BMI, bone density of femoral neck, and 25OHD level of the group without hip fracture were markedly lower than hip fracture group (P < 0.05). The results of logistic regression analysis suggested that age, bone density of femoral neck, and levels of serum 25OHD were independent risk factors for fragile hip fracture on the condition of the bone density of femoral neck having reached the threshold of osteoporosis.

CONCLUSION

Higher age, lower levels of bone density and 25OHD are the main risk factors of hip fracture on the condition of the bone density of femoral neck having reached the threshold of osteoporosis.

[Comprehensive geriatric assessment in a marginal community of Ecuador]

Introduction

Background: older adults suffer from diseases that can affect their functional, psychological and social parameters. The Comprehensive Geriatric Assessment (CGA) is used as an evaluation tool for these parameters through the use of validated, simple and easy-to-apply instruments. Objective: to report the health status of older adults who attend a primary care center in an urban-marginal area of Guayaquil (Ecuador) through CGA, as a first step in order to establish a coordinated care plan in the areas studied. Material and Methods: a cross-sectional assessment of 196 aged subjects with a median age of 70.9 years (83 % females) who attended a Primary Care Community Health Center in Guayaquil. Nutritional, social, demographic, functional, and cognitive variables were assessed. Results: participants had a mean age of 70.9 ± 7.1 years. Demographic variables: 73 % were Afro-Ecuadorian, 69 % had basic education, and 57 % performed no physical activity. Clinical assessment: 47.4 % presented with vision impairment, and 37.8 % with hearing problems; 52 % had nutritional risk and 6 % malnutrition. Social valuation: 13 % had severe social deterioration; 40 % had some cognitive impairment, and 8.2 % had depression; 46.9 % were functionally dependent, and 16.8 % had dynapenia. Conclusions: CGA allows to identify major health problems in this population, which is why it is considered a practical and easy tool to apply in primary care centers in marginal urban populations as a first step to improve health status for this older population, which in recent years is growing significantly in developing countries such as Ecuador.

Individual and cumulative association of commonly used biomarkers on frailty: a cross-sectional analysis of the Mexican Health and Aging Study

Frailty has been recognized as a common condition in older adults, however, there is scarce information on the association between frailty and commonly used biomarkers. The aim of this study was to assess the individual and cumulative association of biomarkers with frailty status. This is a cross-sectional analysis of the 2012 wave of the Mexican Health and Aging Study. A sub-sample of 60-year or older adults with anthropometric measurements was analyzed. Frailty was defined with a 31-item frailty index and those considered frail had a score ≥ 0.21. Biomarkers were further categorized as normal/abnormal and tested both one by one and grouped (according to their usual cutoff values). Adjusted logistic models were performed. A total of 1128 older adults were analyzed and their mean age was 69.45 years and 51.24% of them were women. 26.7% (n = 301) were categorized as frail. Individual biomarkers associated with frailty after adjusting for confounding were: hemoglobin [odds ratio (OR) 1.67, 95% confidence interval (CI) 1.13-2.46, p = 0.009], glycated hemoglobin (OR 2.04, 95% CI 1.54-2.7, p < 0.001) and vitamin D (OR 1.53, 95% CI 1.13-2.07, p = 0.005). Those with ≥ 4 abnormal biomarkers had an independent association with frailty when compared to those without any abnormal biomarker (OR 2.64, 95% CI 1.3-5.25, p = 0.005). Aside from the individual associations of specific biomarkers, our findings show that an incremental association of abnormal biomarkers increases the probability of frailty, accounting for the multidimensional nature of frailty and the possible interplay between components of the system that potentiate to give rise to a negative condition such as frailty.

The role of parathyroid hormone (PTH) and vitamin D in falls and hip fracture type

BACKGROUND

Fragility fractures of the hip are associated with high morbidity and mortality, and represent a rather devastating consequence of osteoporosis. Hip fractures are traditionally investigated as a whole, although it has been recently implied that distinct pathogenic mechanisms may lead either to trochanteric or subcapital fractures.

AIMS

To investigate whether differences exist by hip fracture type with respect to serum 25(OH)D (vitamin D) and parathyroid hormone (PTH) levels, in addition to epidemiological and demographic data, including history of falls.

METHODS

The inclusion criteria were met by 116 patients [48 men and 68 women; mean age 80.8 ± 8.5 (range 62-94) years]. Patients were analyzed according to hip fracture type, history of falls, and vitamin D and PTH status.

RESULTS

Older age, recurrent falls, serum levels of PTH > 65 pg/ml, and severe vitamin D deficiency were found to be associated with trochanteric fractures. Additionally, older age, female gender, PTH > 65 pg/ml, and severe vitamin D deficiency were related to recurrent falls. Meanwhile, patients with absence of PTH response to low vitamin D levels, were not repeated fallers and suffered mostly from subcapital fractures.

DISCUSSION AND CONCLUSION

Elevated PTH levels predispose both to falls and trochanteric fractures, while vitamin D-deficient patients with normal PTH levels are mostly related to subcapital fractures. It is thereby indicated that different pathophysiological processes lie behind subcapital and trochanteric fractures. A better understanding of these mechanisms may assist in the development of prevention strategies for individuals recognized at risk for falls and either type of hip fracture.

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.

Lack of Association Between Vitamin D and Hand Grip Strength in Asians: A Nationwide Population-Based Study

Despite the beneficial role and plausible mechanism of vitamin D on skeletal muscle in animal studies, its association in humans remains a controversial issue due to inconsistent clinical results, especially in older Asians. This was a population-based, cross-sectional study from the Korea National Health and Nutrition Examination Surveys, which enrolled 354 men aged ≥ 50 years and 328 postmenopausal women. Hand grip strength (HGS) was measured using a digital grip strength dynamometer. Low muscle strength was defined based on Korean-specific cut-off point of HGS. Serum 25-hydroxyvitamin D [25(OH)D] levels were 19.4 ± 6.7 and 17.1 ± 7.2 ng/mL in men and women, respectively. Among covariates including age, body mass index, lifestyle factors, and protein intake, age was inversely associated with HGS in both men and women, and protein intake (g/day) was positively associated with HGS only in men. However, the independent correlation between serum 25(OH)D and HGS was not observed, regardless of gender. When subjects were divided into three groups [deficient (25(OH)D < 20 ng/mL; 63.8%), insufficient (20 ≤ 25(OH)D < 30 ng/mL; 30.0%), or sufficient (25(OH)D ≥ 30 ng/mL; 6.2%)], there was no significant difference in HGS among these groups in both men and women. Consistently, serum 25(OH)D was not significantly different between subjects with and without low muscle strength, and there was no independent association of serum 25(OH)D with the risk of low muscle strength in both genders. These findings provide clinical evidence that protective role of vitamin D on human muscle metabolism may not be evident at least in older Asians.

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.

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.

The associations between serum 25-hydroxyvitamin D level and the risk of total fracture and hip fracture

In this meta-analysis, we evaluated the association between serum 25-hydroxyvitamin D (25(OH) vitamin D) level and the risk of total fractures and hip fractures. Low serum 25(OH) vitamin D level is associated with an increased risk of total and hip fractures.

INTRODUCTION

Data on the association between serum 25(OH) vitamin D level and the risk of fractures are conflicting. This study aimed to provide a summary of prospective cohort or nested case-control studies on the association between serum 25(OH) vitamin D level and the risk of total fractures and hip fractures.

METHODS

We identified relevant studies by searching the PubMed, EMBASE, and OVID databases from their inception to June 1, 2016. We included published prospective cohort or nested case-control studies evaluating the associations of serum 25(OH) vitamin D level with the fracture risk. Two reviewers abstracted the data independently. Relative risks (RRs) with 95% confidence intervals (CIs) were derived throughout the whole analysis.

RESULTS

Sixteen prospective cohort studies and three nested case-control studies were included. We found that low serum 25(OH) vitamin D level was significantly associated with the risk of total fractures (RR 1.25, 95% CI 1.06-1.43; I ² = 31.3%, p for heterogeneity = 0.15) and hip fractures (RR 1.48, 95% CI 1.29-1.68; I ² = 0%, p for heterogeneity = 0.51). The hip fracture risk was increased by 40% for each SD decrease in serum 25(OH) vitamin D level (RR 1.40, 95% CI 1.20-1.61; I ² = 0%, p for heterogeneity = 0.51). The per SD decrease in serum 25(OH) vitamin D level was not associated with the increased risk of total fractures (RR 1.14, 95% CI 0.93-1.35; I ² = 63.2%, p for heterogeneity = 0.04).

CONCLUSIONS

Our study suggests that low serum 25(OH) vitamin D level is associated with increased risks of total and hip fractures. In the analyzed studies, the per SD decrease in serum 25(OH) vitamin D level was associated with the hip fracture risk but not with the total fracture risk.