Vitamin D supplementation during rehabilitation in COPD: a secondary analysis of a randomized trial

Vitamin D3 intake modulates diaphragm but not peripheral muscle force in young mice

Recent data support an important role for vitamin D in respiratory health. We tested the hypothesis that dietary vitamin D3 (VD3) intake modulates diaphragm (DIA) strength. Four-week-old female A/J mice (n = 10/group) were randomized to receive diets containing 100 IU VD3/kg (low), 1,000 IU VD3/kg (reference), or 10,000 IU VD3/kg (pharmacologic). After 6 wk of dietary intervention, plasma 25-hydroxyvitamin D3 (25D3) levels, DIA and extensor digitorum longus (EDL) in vitro contractile properties, and fiber cross-sectional area (CSA) were measured. Myosin heavy chain (MHC) composition and Akt/Foxo3A growth signaling were studied in the DIA and tibialis anterior. Mice fed the low, reference, and pharmacologic diets had average 25D3 levels of 7, 21, and 59 ng/ml, respectively. Maximal DIA force, twitch force, and fiber CSA were reduced 26%, 28%, and 10% (P < 0.01), respectively, in mice receiving the low-VD3 diet compared with the reference and pharmacologic diets. EDL force parameters were unaltered by diet. Effects of VD3 intake on DIA force were not observed in mice that began dietary intervention at 12 wk of age. VD3 intake did not alter the MHC composition of the DIA, indicating that decreases in force and CSA in young mice were not due to a switch in fiber type. Paradoxically, low VD3 intake was associated with activation of anabolic signaling in muscle (hyperphosphorylation of Akt and Foxo3A and decreased expression of autophagy marker LC3). These studies identify a potential role of dietary VD3 in regulating DIA development and insulin sensitivity.

Vitamin D supplementation to prevent depression and poor physical function in older adults: Study protocol of the D-Vitaal study, a randomized placebo-controlled clinical trial

BACKGROUND

Depressive symptoms and decreased physical functioning are interrelated conditions and common in older persons, causing significant individual and societal burden. Evidence suggests that vitamin D supplementation may be beneficial for both mental and physical functioning. However, previous randomized controlled trials have yielded inconsistent results and often had suboptimal designs. This study examines the effect of vitamin D supplementation on both depressive symptoms and physical functioning in a high-risk population of older persons with low vitamin D status.

METHODS/DESIGN

The D-Vitaal study is a randomized, double-blind, placebo-controlled trial investigating the effects of a daily dose of 1200 IU vitamin D3 versus placebo for one year on depressive symptoms and physical functioning (primary outcomes) in older adults. Participants (N = 155, age 60-80 years) were recruited from the general population. Eligibility criteria included the presence of depressive symptoms, ≥1 functional limitation and serum 25-hydroxyvitamin D levels between 15 and 50/70 nmol/L (depending on season). Secondary outcomes include incidence of major depressive disorder, anxiety symptoms, health-related quality of life, cognitive function and cost-effectiveness of the intervention.

DISCUSSION

With this study, we aim to elucidate the effects of vitamin D supplementation on depressive symptoms and physical functioning in older persons who are at high risk of developing more substantial mental and physical problems. If effective, vitamin D supplementation can be a preventive intervention strategy that is easy to implement in the primary care setting.

TRIAL REGISTRATION

Netherlands Trial Register NTR3845. Registered 6 February 2013.

Prevention of exacerbations in patients with COPD and vitamin D deficiency through vitamin D supplementation (PRECOVID): a study protocol

Background

Vitamin D is well known for its function in calcium homeostasis and bone mineralisation, but is increasingly studied for its potential immunomodulatory properties. Vitamin D deficiency is a common problem in patients with COPD. Previous studies have not demonstrated a beneficial effect of vitamin D on exacerbation rate in COPD patients. However, subgroup analyses suggested protective effects in vitamin D deficient patients. Our objective is to assess the effect of vitamin D supplementation on exacerbation rate specifically in vitamin D deficient COPD patients.

Methods/Design

We will perform a randomised, multi-center, double-blind, placebo-controlled intervention study. The study population consists of 240 COPD patients aged 40 years and older with vitamin D deficiency (25-hydroxyvitamin D concentration < 50 nmol/L). Participants will be recruited after an exacerbation and will be randomly allocated in a 1:1 ratio to receive vitamin D3 16800 IU or placebo orally once a week during 1 year. Participants will receive a diary card to register the incidence of exacerbations and changes in medication during the study period. Visits will be performed at baseline, at 6 months and at 12 months after randomisation. Participants will undergo spirometry, measurement of total lung capacity and assessment of maximal respiratory mouth pressure. Several physical performance and hand grip strength tests will be performed, questionnaires on quality of life and physical activity will be filled in, a nasal secretion sample and swab will be obtained and blood samples will be taken. The primary outcome will be exacerbation rate.

Discussion

This study will be the first RCT aimed at the effects of vitamin D supplementation on exacerbation rate in vitamin D deficient COPD patients. Also, in contrast to earlier studies that used infrequent dosing regimens, our trial will study effects of a weekly dose of vitamin D supplementation. Secondly, the immunomodulatory effects of vitamin D on host immune response of COPD patients and underlying mechanisms will be studied. Finally, the effects on physical functioning will be examined.

Trial registration

This trial is registered in ClinicalTrials.gov, ID number NCT02122627. Date of Registration April 2014.

Vitamin D deficiency is associated with the severity of COPD: a systematic review and meta-analysis

Purpose

To explore the association between host serum 25-hydroxyvitamin D (25(OH)D) and the susceptibility and severity of COPD.

Methods

Previous studies on the association between host 25(OH)D and the susceptibility and severity of COPD were collected on the basis of a systematic literature search of PubMed and Web of Science up to June 2015. Continuous variable data were presented as standard mean difference (SMD) or weighted mean difference with 95% confidence interval (CI). The dichotomous variable data were analyzed as relative ratio (RR) or odds ratio with 95% CI for cohort and case-control studies. A systematic review was conducted to understand the curative and side effects of vitamin D intake.

Results

A total of 18 studies including eight cohort, five case-control, and five randomized studies met the inclusion criteria. The serum level of 25(OH)D in COPD patients was comparable with controls with a pooled SMD of 0.191 (95% CI: −0.126 to 0.508, P=0.237) based on pooled analyses of cohort studies. However, the serum level of 25(OH)D in COPD patients was lower with a pooled SMD of 0.961 (95% CI: 0.476–1.446, P<0.001) compared with controls based on pooled analyses of case-control studies. The deficiency rates of 25(OH)D were comparable between controls and COPD patients with a pooled RR of 0.955 (95% CI: 0.754–1.211, P=0.705) based on analyses of cohort studies, and the same results were observed based on pooled analyses of case-control studies. Interestingly, the deficiency rate of 25(OH)D was significantly lower in moderate or severe COPD patients with a pooled RR of 0.723 (95% CI: 0.632–0.828, P<0.001) compared with that in mild COPD patients. The same results were obtained from the pooled analysis between moderate and severe COPD patients. The four randomized studies showed that vitamin D intake provided benefit for COPD patients.

Conclusion

Low serum levels of 25(OH)D were not associated with COPD susceptibility, but the high deficiency rate of 25(OH)D was associated with COPD severity. Vitamin D supplementation may prevent COPD exacerbation.

Vitamin D deficiency and airflow limitation in the Baltimore Longitudinal Study of Ageing

BACKGROUND

Vitamin D deficiency is common in patients with chronic obstructive pulmonary disease (COPD) and has also been linked to comorbidities often present in COPD.

AIM

The aim of this study was to investigate whether vitamin D deficiency was related specifically to airflow limitation or whether vitamin D deficiency was determined by conditions that frequently coexist with COPD: insulin resistance, hypertension, anaemia, obesity and hypercholesterolaemia.

METHODS

For this cross-sectional analysis, we included 897 subjects from the Baltimore Longitudinal Study of Aging. Subjects taking vitamin D supplements were excluded. Airflow limitation was defined as FEV1 /FVC < lower limit of normal. Logistic regression was used to assess the association between vitamin D deficiency (25-hydroxy vitamin D < 20 ng/mL) and possible determinants.

RESULTS

Vitamin D deficiency was not specific for subjects with airflow limitation. Body mass index (BMI) (OR: 1.05, P < 0.03) and obesity (BMI > 30 kg/m(2)) (OR: 1.9, P < 0.002) were significantly associated with vitamin D deficiency in the adjusted multivariate regression analysis. Physical activity was associated with a decreased risk of vitamin D deficiency.

CONCLUSIONS

Airflow limitation was not an independent determinant of vitamin D deficiency. The effect of weight loss and increased physical activity on vitamin D levels should be investigated further in intervention studies.

Effect of hospital use of oral nutritional supplementation on length of stay, hospital cost, and 30-day readmissions among Medicare patients with COPD

BACKGROUND

COPD is a leading cause of death and disability in the United States. Patients with COPD are at a high risk of nutritional deficiency, which is associated with declines in respiratory function, lean body mass and strength, and immune function. Although oral nutritional supplementation (ONS) has been associated with improvements in some of these domains, the impact of hospital ONS on readmission risk, length of stay (LOS), and cost among hospitalized patients is unknown.

METHODS

Using the Premier Research Database, we first identified Medicare patients aged ≥ 65 years hospitalized with a primary diagnosis of COPD. We then identified hospitalizations in which ONS was provided, and used propensity-score matching to compare LOS, hospitalization cost, and 30-day readmission rates in a one-to-one matched sample of ONS and non-ONS hospitalizations. To further address selection bias among patients prescribed ONS, we also used instrumental variables analysis to study the association of ONS with study outcomes. Model covariates included patient and provider characteristics and a time trend.

RESULTS

Out of 10,322 ONS hospitalizations and 368,097 non-ONS hospitalizations, a one-to-one matched sample was created (N = 14,326). In unadjusted comparisons in the matched sample, ONS use was associated with longer LOS (8.7 days vs 6.9 days, P < .0001), higher hospitalization cost ($14,223 vs $9,340, P < .0001), and lower readmission rates (24.8% vs 26.6%, P = .0116). However, in instrumental variables analysis, ONS use was associated with a 1.9-day (21.5%) decrease in LOS, from 8.8 to 6.9 days (P < .01); a hospitalization cost reduction of $1,570 (12.5%), from $12,523 to $10,953 (P < .01); and a 13.1% decrease in probability of 30-day readmission, from 0.34 to 0.29 (P < .01).

CONCLUSIONS

ONS may be associated with reduced LOS, hospitalization cost, and readmission risk in hospitalized Medicare patients with COPD.

Relationship of vitamin D status with lung function and exercise capacity in COPD

BACKGROUND AND OBJECTIVE

The relationship between blood vitamin D level and clinical parameters in patients with chronic obstructive pulmonary disease (COPD) has been reported with conflicting results. We explored the effects of vitamin D on clinical characteristics of patients with COPD in Korea.

METHODS

The study population comprised 193 patients with COPD from Korean Obstructive Lung Disease Cohort. The plasma level of 25-OH vitamin D3 (25-OH-VitD3) was measured every year along with various clinical parameters such as lung function, 6-min walking (6MW) distance, quality of life, exacerbations and emphysema index. Generalized estimating equations and linear mixed model were used for statistical analysis.

RESULTS

Of the 193 patients, 12 (6.2%), 28 (14.5%) and 153 (79.3%) were categorized into normal, insufficiency and deficiency groups. Clustered analysis showed that the plasma 25-OH-VitD3 level was associated with the post-bronchodilator ratio of force expiratory volume in 1 s/forced vital capacity (FEV1 /FVC) (estimated = 0.001; P = 0.022). The vitamin D deficiency group showed lower FEV1 (estimated = -0.129, P = 0.043), FEV1 % predicted (estimated = -4.994, P = 0.029) and FEV1 /FVC ratio (estimated = -0.048, P = 0.001) than did the non-deficiency group. The 6MW distance tended to be shorter in deficiency group (estimated = -17.26, P = 0.069) than in non-deficiency group. Quality of life, exacerbation and emphysema index were not associated with plasma 25-OH-VitD3 level.

CONCLUSIONS

We demonstrated a high prevalence of vitamin D deficiency in Korean patients with COPD and a significant relationship between vitamin D deficiency and airflow limitation. The exercise capacity tended to be decreased in the vitamin D deficiency group.

Association Between Vitamin D Status and Weaning From Prolonged Mechanical Ventilation in Survivors of Critical Illness

BACKGROUND

In this study, we examined the association between 25-hydroxyvitamin D (25(OH)D) concentration and successful weaning from mechanical ventilation in a cohort of ICU survivors requiring prolonged mechanical ventilation.

METHODS

This was a retrospective cohort study of ICU survivors admitted to a long-term acute care hospital. Demographic data were extracted from medical records, including 25(OH)D concentrations drawn on admission. Subjects were divided into 2 groups based on their 25(OH)D concentrations (deficient, < 20 ng/mL; not deficient, ≥ 20 ng/mL), and associations between 25(OH)D concentration and successful weaning were calculated.

RESULTS

A total of 183 subjects were studied. A high prevalence of 25(OH)D deficiency was found (61%, 111/183). No association was found between 25(OH)D concentration and weaning from mechanical ventilation. Increased comorbidity burden (Charlson comorbidity index) was associated with decreased odds of weaning (odds ratio of 0.50, 95% CI 0.25-0.99, P = .05).

CONCLUSIONS

Vitamin D deficiency is common in ICU survivors requiring prolonged mechanical ventilation. Surprisingly, there was no significant relationship between 25(OH)D concentration and successful weaning. This finding may be due to the low 25(OH)D concentrations seen in our subjects. Given what is known about vitamin D and lung function and given the low vitamin D concentrations seen in patients requiring long-term ventilatory support, interventional studies assessing the effects of 25(OH)D supplementation in these patients are needed.

Effects of Vitamin D Intake on FEV1 and COPD Exacerbation: A Randomized Clinical Trial Study

Aim:

This study aimed to evaluate the effects of vitamin D intake on COPD exacerbation and FEV1 in the patients with severe and very severe COPD.

Methods:

This double blind placebo control randomized clinical trial study was done in the Ashayer university hospital in Khorramabad in 2012. Eighty eight patients with severe and very severe COPD were randomly selected from those who recoursed to the internal medicine clinic of Ashayer hospital. They were randomly allocated to case and placebo group. The patients received routine treatment for COPD. Along with the routine treatment, placebo group received 100,000 IU of oral vitamin D per month, for 6 months. Data was analyzed using SPSS computer software, paired t-test, independent t-test, non parametric t-test and Pearson correlation coefficients.

Results:

In each group, there were 44 patients. After the intervention, there were significant differences in FEV1 and the number of COPD exacerbation between the case and control group patients. Also, after the study, in the case group, FEV1 was increased and the number of COPD exacerbation was decreased significantly.

Conclusion:

Vitamin D intake decreased COPD exacerbation and improved FEV1 in the patients with severe and very severe COPD. It is suggested that baseline serum vitamin D levels will recorded in similar studies and the effect of vitamin D intake will evaluated regarding the baseline serum vitamin D levels.

Vitamin D status and distribution in patients with chronic obstructive pulmonary disease versus healthy controls

BACKGROUND

Vitamin D has a potential to modulate inflammatory response against noxious particles in patients with chronic obstructive pulmonary disease (COPD). The present study was conducted to determine the status of serum vitamin D in COPD versus healthy group.

METHODS

The patients presented to the outpatient pulmonary clinic of Ayatollah Rouhani Hospital, Babol Iran. Diagnosis of COPD was confirmed based on airflow limitation defined as FEV1/FVC ratio <70% and FEV1< 80% of predicted. All eligible patients aged ≥ 40 years old entered the study. Pulmonary infection, tuberculosis, pleural effusion, congestive heart failure, pulmonary hypertension and embolism, restrictive airway disease, conditions leading changes in vitamin D metabolism and absorption were excluded. Serum 25-hydroxyvitamin D (25-OHD) was determined by electrocheminluminescence method and levels <20, 20-29, and ≥30ng/ml were considered as deficiency, insufficiency, and sufficiency. In statistical analysis, the frequency of serum 25-OHD deficiency and insufficiency in patients were compared regarding age of ≤ 50 or >50 years old. All patients were males and age and sex-matched controls were selected among healthy subjects accompanied COPD patients.

RESULTS

Ninety patients and 100 controls with respective mean (±SD) age of 64.8±11.7 and 62.6±11.7 years old (P=0.19) were studied. Compared with control, proportions of serum 25-OHD deficiency and insufficiency in patients >50 years were higher and deficiency was lower (61.5% vs 87.5%, P=0.11).

CONCLUSION

These findings indicate that a significant proportion of young COPD patients have insufficient serum 25-OHD. Regarding a positive relationship between 25-OHD and FEV1 in COPD, these findings highlight serum 25-OHD assessment in COPD for recognizing high risk patients.

Severe vitamin D deficiency is associated with frequent exacerbations and hospitalization in COPD patients

BACKGROUND

Acute exacerbations of COPD (AECOPD) are common and strongly influence disease severity and relative healthcare costs. Vitamin D deficiency is frequent among COPD patients and its contributory role in disease exacerbations is widely debated. Our aim was to assess the relationship of serum vitamin D levels with COPD severity and AECOPD.

METHODS

Serum vitamin D (25-hydroxyvitamin D) levels were measured in 97 COPD patients and related to lung function, comorbidities, FEV1 decline, AECOPD and hospital admission during the previous year.

RESULTS

Most patients (96%) had vitamin D deficiency, which was severe in 35 (36%). No significant relationship was found between vitamin D and FEV1 or annual FEV1 decline. No difference between patients with and without severe vitamin D deficiency was found in age, gender, BMI, smoking history, lung function, and comorbidities, apart from osteoporosis (60.9% in severe deficiency vs 22.7%, p = 0.001). In multiple logistic regression models, severe deficiency was independently associated with AECOPD [adjusted odds ratios (aOR) of 30.5 (95% CI 5.55, 168), p < 0.001] and hospitalization [aOR 3.83 (95% CI 1.29, 11.4), p = 0.02]. The odds ratio of being a frequent exacerbator if having severe vitamin D deficiency was 18.1 (95% CI 4.98, 65.8) (p < 0.001), while that of hospitalization was 4.57 (95% CI 1.83, 11.4) (p = 0.001).

CONCLUSIONS

In COPD patients severe vitamin D deficiency was related to more frequent disease exacerbations and hospitalization during the year previous to the measurement of vitamin D. This association was independent of patients' characteristics and comorbidities.

The effects of vitamin D on skeletal muscle strength, muscle mass, and muscle power: a systematic review and meta-analysis of randomized controlled trials

CONTEXT

There is growing evidence that vitamin D plays a role on several tissues including skeletal muscle.

OBJECTIVE

The aim was to summarize with a meta-analysis, the effects of vitamin D supplementation on muscle function.

DATA SOURCES

A systematic research of randomized controlled trials, performed between 1966 and January 2014 has been conducted on Medline, Cochrane Database of Systematics Reviews, Cochrane Central Register of Controlled and completed by a manual review of the literature and congressional abstracts.

STUDY SELECTION

All forms and doses of vitamin D supplementation, with or without calcium supplementation, compared with placebo or control were included. Out of the 225 potentially relevant articles, 30 randomized controlled trials involving 5615 individuals (mean age: 61.1 years) met the inclusion criteria.

DATA EXTRACTION

Data were extracted by two independent reviewers.

DATA SYNTHESIS

Results revealed a small but significant positive effect of vitamin D supplementation on global muscle strength with a standardized mean difference (SMD) of 0.17 (P = .02). No significant effect was found on muscle mass (SMD 0.058; P = .52) or muscle power (SMD 0.057; P = .657). Results on muscle strength were significantly more important with people who presented a 25-hydroxyvitamin D level <30 nmol/L. Supplementation seems also more effective on people aged 65 years or older compared to younger subjects (SMD 0.25; 95% CI 0.01 to 0.48 vs SMD 0.03; 95% CI -0.08 to 0.14).

CONCLUSIONS

Vitamin D supplementation has a small positive impact on muscle strength, but additional studies are needed to define optimal treatment modalities, including dose, mode of administration, and duration.

An official American Thoracic Society/European Respiratory Society statement: update on limb muscle dysfunction in chronic obstructive pulmonary disease

BACKGROUND

Limb muscle dysfunction is prevalent in chronic obstructive pulmonary disease (COPD) and it has important clinical implications, such as reduced exercise tolerance, quality of life, and even survival. Since the previous American Thoracic Society/European Respiratory Society (ATS/ERS) statement on limb muscle dysfunction, important progress has been made on the characterization of this problem and on our understanding of its pathophysiology and clinical implications.

PURPOSE

The purpose of this document is to update the 1999 ATS/ERS statement on limb muscle dysfunction in COPD.

METHODS

An interdisciplinary committee of experts from the ATS and ERS Pulmonary Rehabilitation and Clinical Problems assemblies determined that the scope of this document should be limited to limb muscles. Committee members conducted focused reviews of the literature on several topics. A librarian also performed a literature search. An ATS methodologist provided advice to the committee, ensuring that the methodological approach was consistent with ATS standards.

RESULTS

We identified important advances in our understanding of the extent and nature of the structural alterations in limb muscles in patients with COPD. Since the last update, landmark studies were published on the mechanisms of development of limb muscle dysfunction in COPD and on the treatment of this condition. We now have a better understanding of the clinical implications of limb muscle dysfunction. Although exercise training is the most potent intervention to address this condition, other therapies, such as neuromuscular electrical stimulation, are emerging. Assessment of limb muscle function can identify patients who are at increased risk of poor clinical outcomes, such as exercise intolerance and premature mortality.

CONCLUSIONS

Limb muscle dysfunction is a key systemic consequence of COPD. However, there are still important gaps in our knowledge about the mechanisms of development of this problem. Strategies for early detection and specific treatments for this condition are also needed.

Novel drug targets for asthma and COPD: lessons learned from in vitro and in vivo models

Asthma and chronic obstructive pulmonary disease (COPD) are highly prevalent respiratory diseases characterized by airway inflammation, airway obstruction and airway hyperresponsiveness. Whilst current therapies, such as β-agonists and glucocorticoids, may be effective at reducing symptoms, they do not reduce disease progression. Thus, there is a need to identify new therapeutic targets. In this review, we summarize the potential of novel targets or tools, including anti-inflammatories, phosphodiesterase inhibitors, kinase inhibitors, transient receptor potential channels, vitamin D and protease inhibitors, for the treatment of asthma and COPD.

Musculoskeletal disorders in chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) is a lung disease characterized by airway obstruction and inflammation but also accompanied by several extrapulmonary consequences, such as skeletal muscle weakness and osteoporosis. Skeletal muscle weakness is of major concern, since it leads to poor functional capacity, impaired health status, increased healthcare utilization, and even mortality, independently of lung function. Osteoporosis leads to fractures and is associated with increased mortality, functional decline, loss of quality of life, and need for institutionalization. Therefore, the presence of the combination of these comorbidities will have a negative impact on daily life in patients with COPD. In this review, we will focus on these two comorbidities, their prevalence in COPD, combined risk factors, and pathogenesis. We will try to prove the clustering of these comorbidities and discuss possible preventive or therapeutic strategies.

The role of vitamin D in chronic obstructive pulmonary disease, asthma and other respiratory diseases

There has been growing interest in recent years in the extraosseous effects of vitamin D. In this article, we review the physiology of vitamin D, the physiopathological effects associated with vitamin D deficit and the available evidence on its etiopathogenic role in respiratory diseases. Given the pleiotropic actions of vitamin D, it is biologically plausible that the deficit of this vitamin could play a pathogenic role of in the development of various respiratory diseases. However, the many epidemiological studies that have shown an association between low vitamin D levels and a higher risk of developing various respiratory diseases or a poorer prognosis if they do appear, were unable to show causality. Post-hoc analyses of some clinical trials, particularly in chronic obstructive pulmonary disease (COPD) and asthma, appear to suggest that some patient subtypes may benefit from correction of a vitamin D deficit. In this respect, it would be interesting to determine if the interindividual differences found in the effect of vitamin D deficit and responses to correcting this deficit could be explained by the genetic variants involved in vitamin D metabolism. Ultimately, only appropriately designed clinical trials will determine whether 25-OHD supplements can prevent or improve the course of the various respiratory diseases in which an epidemiological association between prognosis and vitamin D deficit has been described.

Beneficial role of vitamin D3 in the prevention of certain respiratory diseases

There is evidence of aberrations in the vitamin D-endocrine system in subjects with respiratory diseases. Vitamin D deficiency is highly prevalent in patients with respiratory diseases, and patients who receive vitamin D have significantly larger improvements in inspiratory muscle strength and maximal oxygen uptake. Studies have provided an opportunity to determine which proteins link vitamin D to respiratory pathology, including the major histocompatibility complex class II molecules, vitamin D receptor, vitamin D-binding protein, chromosome P450, Toll-like receptors, poly(ADP-ribose) polymerase-1, and the reduced form of nicotinamide adenine dinucleotide phosphate. Vitamin D also exerts its effect on respiratory diseases through cell signaling mechanisms, including matrix metalloproteinases, mitogen-activated protein kinase pathways, the Wnt/β-catenin signaling pathway, prostaglandins, reactive oxygen species, and nitric oxide synthase. In conclusion, vitamin D plays a significant role in respiratory diseases. The best form of vitamin D for use in the treatment of respiratory diseases is calcitriol because it is the active metabolite of vitamin D3 and modulates inflammatory cytokine expression. Further investigation of calcitriol in respiratory diseases is needed.

Optimal vitamin D status: a critical analysis on the basis of evidence-based medicine

CONTEXT

Public health authorities around the world recommend widely variable supplementation strategies for adults, whereas several professional organizations, including The Endocrine Society, recommend higher supplementation.

METHODS

We analyzed published randomized controlled clinical trials to define the optimal intake or vitamin D status for bone and extraskeletal health.

CONCLUSIONS

The extraskeletal effects of vitamin D are plausible as based on preclinical data and observational studies. However, apart from the beneficial effects of 800 IU/d of vitamin D3 for reduction of falls in the elderly, causality remains yet unproven in randomized controlled trials (RCTs). The greatest risk for cancer, infections, cardiovascular and metabolic diseases is associated with 25-hydroxyvitamin D (25OHD) levels below 20 ng/mL. There is ample evidence from RCTs that calcium and bone homeostasis, estimated from serum 1,25-dihydroxyvitamin D and PTH, calcium absorption, or bone mass, can be normalized by 25OHD levels above 20 ng/mL. Moreover, vitamin D supplementation (800 IU/d) in combination with calcium can reduce fracture incidence by about 20%. Such a dose will bring serum levels of 25OHD above 20 ng/mL in nearly all postmenopausal women. Based on calculations of the metabolic clearance of 25OHD, a daily intake of 500-700 IU of vitamin D3 is sufficient to maintain serum 25OHD levels of 20 ng/mL. Therefore, the recommendations for a daily intake of 1500-2000 IU/d or serum 25OHD levels of 30 ng or higher for all adults or elderly subjects, as suggested by The Endocrine Society Task Force, are premature. Fortunately, ongoing RCTs will help to guide us to solve this important public health question.

Undernutrition in patients with COPD and its treatment

Chronic obstructive pulmonary disease (COPD) is a chronic inflammatory disorder of the lung and whole body caused mainly by tobacco smoking. Patients with advanced COPD are in a state of undernutrition, referred to as pulmonary cachexia; the exercise performance and quality of life (QOL) of these patients are deteriorated, the vital prognosis is unfavorable, and the medico-economic burden posed by poorly nourished COPD patients is high. The mainstays of COPD treatment are pharmacotherapy, mainly with bronchodilators, and non-pharmacotherapeutic approaches such as respiratory rehabilitation and nutrition counseling. Nutritional supplement therapy, consisting primarily of high calorie intake, has been demonstrated to be effective for maintaining and improving the muscle strength and exercise tolerance in poorly nourished COPD patients. The efficacy of intake of various nutrients, besides a high calorie intake, for amelioration of the disease state of COPD has also been reported. The roles of adipokines in the pathophysiology of COPD have begun to receive attention recently, and not only their regulatory effects on appetite and nutritional status, but also their influence on systemic inflammation have been increasingly clarified. We review the papers on COPD and nutrition and discuss the role of nutritional supplement therapy in the treatment of COPD.

Supplemental vitamin D and physical performance in COPD: a pilot randomized trial

Background

Low 25-hydroxyvitamin D (25[OH]D) levels, commonly observed in chronic obstructive pulmonary disease (COPD), are associated with muscle weakness in elderly populations, and vitamin D supplementation appears to improve muscle strength and decrease falls in older individuals. We tested the effect of vitamin D supplementation on physical performance in patients with COPD.

Methods

Patients were randomized to daily cholecalciferol (2000 IU) or placebo for 6 weeks. The primary outcome was the 6-week change in Short Physical Performance Battery (SPPB) score. Secondary outcomes included changes in the St George’s Respiratory Questionnaire (SGRQ) score, and serum 25(OH)D.

Results

Thirty-six participants (mean age 68 years, all Caucasian males, mean forced expiratory volume in one second 33% of predicted) completed the study. Despite an increase in 25(OH)D levels in the intervention arm to a mean of 32.6 ng/mL (versus 22.1 ng/mL in the placebo arm), there was no difference in improvements in either SPPB scores (0.3 point difference; 95% confidence interval −0.8 to 1.5; P = 0.56) or SGRQ scores (2.3 point difference; 95% confidence interval −2.3 to 6.9; P = 0.32).

Conclusion

Among patients with severe COPD, 2000 IU of daily vitamin D for 6 weeks increased 25(OH)D to a level widely considered as normal. However, compared with placebo, short-term vitamin D supplementation had no discernible effect on a simple measure of physical performance.