Serum Vitamin D Is Significantly Inversely Associated with Disease Severity in Caucasian Adults with Obstructive Sleep Apnea Syndrome

Roles of vitamins and nutrition in obstructive sleep apnea

INTRODUCTION

Obstructive sleep apnea (OSA) is the most common sleep-related breathing disorder, with a prevalence that rises alongside with the increasing prevalence of obesity. OSA is characterized by a low-inflammatory state and is followed by cardiovascular and metabolic sequelae. Continuous positive airway pressure (CPAP) represents the cornerstone of treatment for severe OSA. However, poor compliance with CPAP treatment renders OSA treatment a challenging venture. Weight loss and exercise are recommended as adjunctive treatment options for OSA. Several diets have proven to facilitate weight loss, and to alleviate the inflammatory status in patients with OSA. Moreover, several vitamins exhibit antioxidant properties that beneficially affect OSA pathology and reduce the risk of cardiovascular complications.

AREA COVERED

This narrative review aims to summarize the current knowledge regarding the effect of nutrition and vitamin deficiencies on OSA. Included were publications, relevant to the topic, with different types of design (i.e. cross-sectional studies, cohort studies, clinical trials, systematic reviews, meta-analyses, etc.) and indexed in PubMed database until 31 March 2024.

EXPERT OPINION

In addition to weight loss, other food components, such as proteins, carbohydrates, anti-inflammatory agents, vitamins A, B, C, D, E, and sodium, may play a beneficial role in the incidence and severity of OSA.

Serum 25(OH)D levels and obstructive sleep apnea syndrome severity in patients without comorbidities: a systematic review and meta-analysis

PURPOSE

The aim of the present systematic review was to corroborate existing evidence on how serum25(OH)D levels affect obstructive sleep apnea syndrome (OSAS) severity in the absence of comorbidities.

METHODS

From inception to May 2024, PubMed, Scopus, and Embase electronic databases were systematically screened to identify randomized controlled trials (RCTs), quasi-RCTs, prospective, and retrospective studies. A strict search protocol was applied following the application of PROSPERO, under the registration number CRD42023468744. The formulated question based on PICO process was: "how do serum25(OH)D levels affect the severity of OSAS or result in enhanced sleep function?". Collected results were finally reviewed for meta-analysis and quality assessment according to the ROBINS-I tool.

RESULTS

Data from 24 studies were pooled and divided into 15 case-control studies and 9 cross-sectional studies. All studies involved a total of 2640 OSAS subjects and 933 healthy subjects. All studies underwent qualitative analysis whereas only 20 were collected for meta-analysis. Mild OSAS showed 25(OH)D levels non-statistically significant (P = 0.12) than the healthy patients whereas moderate OSAS (P = 0.004) and severe OSAS (P < 0.001) differed significantly from control groups. Meta-regression suggested that OSAS severity correlated inversely to the deficiency of 25(OH)D serum levels. Qualitative assessment and Egger's test revealed an elevated risk of bias but low presence of publication bias, respectively.

CONCLUSION

Serum levels of 25(OH)D were observed to be inversely proportional to OSAS severity in patients without coexisting morbidities. 25(OH)D levels in mild OSAS patients were not significantly different from non-OSAS patients, suggesting vitamin supplementation to improve potential sleep disorders.

Exploring the link between vitamin D deficiency and obstructive sleep apnea: A comprehensive review

Despite the high prevalence and significant health burden of obstructive sleep apnea (OSA), its underlying pathophysiology remains incompletely understood. This comprehensive review explores the emerging connection between vitamin D deficiency and OSA, discusses potential mechanisms underlying this association, and explores the therapeutic implications of these findings. Recent research has consistently highlighted the high incidence of vitamin D deficiency among patients with OSA, which often occurs independently of geographical location. This suggests that factors beyond lack of sunlight exposure may be involved. This review also discusses how reduced vitamin D may be associated with more severe manifestations of OSA. In addition, it explores the potentiality of using vitamin D supplements as a therapeutic strategy for OSA, noting that some studies have found improvements in sleep quality and a reduction in OSA severity. Potential mechanisms are proposed, including the role of vitamin D deficiency in promoting inflammation, oxidative stress, hypoxia, impairing immune function, muscle function, and gene polymorphism of vitamin D receptors, all of which could contribute to the pathogenesis of obstructive sleep apnea. The paper underscores the need for future research to validate these observations, to determine optimal vitamin D supplementation dosage and duration, to explore potential side effects and risks, and to investigate potential interactions with other treatments.

Vitamin D deficiency: A forgotten aspect in sleep disorders? A critical update

Over the past few years, there has been a surge in interest regarding the connection between sleep duration and quality, sleep disorders, mainly Obstructive sleep apnoea (OSA) and Vitamin D. There is growing evidence to support a new role of Vitamin D in the maintenance and regulation of optimal sleep. Furthermore, a notable link has been identified between OSA and a decrease in serum Vitamin D levels, which appears to intensify as the severity of sleep apnea worsens. Vitamin D status could also potentially serve as a mediator or provide an explanation for the association between OSA and cardiometabolic morbidity, but the current state of research in this area is inadequate. Studies have indicated that the supplementation of Vitamin D can optimize sleep quality, presenting more proof of the connection between insufficient vitamin D levels and sleep disorders. However, it is unclear whether low serum Vitamin D levels are a contributing factor to OSA development or if OSA predisposes individuals to Vitamin D deficiency. As a result, various studies have endeavored to examine the complex relationship between OSA and Vitamin D deficiency. In children and adolescents, while data is limited, there seems also to be a link between sleep disorders and Vitamin D levels. Therefore, the objective of this review is to provide a comprehensive overview of the current evidence on the association between Vitamin D and sleep disorders in both adults and children.

Is there an association between serum 25-hydroxyvitamin D concentrations and obstructive sleep apnoea? A cross-sectional analysis of NHANES 2007-2008 data

OBJECTIVES

The study aimed to investigate the relationship between serum 25-hydroxyvitamin D (25(OH)D) concentrations and obstructive sleep apnoea (OSA) and to assess the confounding effect of body mass index (BMI) on this relationship.

DESIGN

This was a cross-sectional analysis using data from the 2007-08 National Health and Nutrition Examination Survey (NHANES).

SETTING

Data were sourced from NHANES, a continuous survey sponsored by the Centres for Disease Control and Prevention, covering residents from 15 urban areas in the United States of America(USA).

PARTICIPANTS

The study included 4901 participants aged 16 years and older who had completed 25(OH)D data and responses to the OSA questionnaire.

MAIN EXPOSURE MEASURE

Serum 25(OH)D concentrations were measured using liquid chromatography-tandem mass spectrometry.

MAIN OUTCOME MEASURE

The primary outcome was the self-reported diagnosis of OSA from questionnaires.

RESULTS

After adjusting for age, sex and race (model 1), a significant negative association was observed between 25(OH)D and OSA (β=-3.21, 95% CI: -6.17 to -0.26). However, this association was no longer significant after further adjustment for BMI (model 2) (β=1.47, 95% CI: -1.48, 4.42). In the fully adjusted model (model 3), there was no significant association between 25(OH)D and OSA (β=0.92, 95% CI: -1.93, 3.76). Subgroup analyses stratified by sex, age, race or BMI also revealed no significant associations between 25(OH)D and OSA.

CONCLUSIONS

The study found no significant association between 25(OH)D and OSA. The observed correlation between lower levels of 25(OH)D and OSA may be due to confounding factors, such as higher BMI in the OSA group. Therefore, improving obesity management in OSA patients may be necessary to prevent 25(OH)D insufficiency. This underscores the importance of comprehensive management of both OSA and obesity to promote optimal health outcomes.

Distribution characteristics of intestinal flora in patients with OSAHS and the relationship between different intestinal flora and sleep disorders, hypoxemia and obesity

OBJECTIVE

To investigate the distribution characteristics of intestinal flora in patients with obstructive sleep apnoea hypopnea syndrome (OSAHS) of different severities and the relationship between different intestinal flora and sleep structure disorder, hypoxemia and obesity.

METHODS

A total of 25 healthy volunteers and 80 patients with OSAHS were enrolled in this study. The control group was healthy, and the experimental group comprised patients with OSAHS. The apnoea-hypopnea index (AHI), minimum saturation of peripheral oxygen (SpO2min), mean saturation of peripheral oxygen, body mass index, maximum apnoea time and other indicators were collected in clinical practice. The patients with OSAHS were divided into 20 mild and 42 moderate OSAHS cases, as well as 18 patients with severe OSAHS according to the AHI classification. Bioinformatics-related statistics were analysed using the QIIME2 software, and clinical data were analysed with the SPSS 22.0 software.

RESULTS

The changes in microbial alpha diversity in the intestinal flora of patients with OSAHS showed that richness, diversity and evenness decreased, but the beta diversity did not change significantly. The Thermus Anoxybacillus, Anaerofustis, Blautia, Sediminibacterium, Ralstonia, Pelomonas, Ochrobactrum, Thermus Sediminibacterium, Ralstonia, Coccidia, Cyanobacteria, Anoxic bacilli and Anaerobes were negatively correlated with AHI (r = -0.38, -0.36, -0.35, -0.33, -0.31, -0.29, -0.22, -0.18) and positively correlated with SpO2min (r =0.38, 0.2, 0.25, 0.22, 0.24, 0.11, 0.23, 0.15).

CONCLUSION

Some bacteria showed a significant correlation with clinical sleep monitoring data, which provides a possibility for the assessment of disease risk, but the mechanisms of their actions in the intestinal tract are not clear at present. Further research and observations are needed.

Obstructive sleep apnea and vitamin D level: Has the dust settled?

Obstructive sleep apnea and vitamin D deficiency are associated with multiple complications with increased morbidity and mortality. However, the relationship between these two entities remains unclear, with clinical studies demonstrating contradictory results. This narrative review aims to present the current evidence and understanding of this relationship and discuss the possible mechanisms linking these two disease entities. Finally, we summarize and propose areas of opportunity for future research.

Obstructive sleep apnea and vitamin D: an updated systematic review and meta-analysis

PURPOSE  : Obstructive sleep apnea (OSA) is a chronic, sleep-related breathing disorder which leads to increased cardiovascular risks. Vitamin D deficiency is associated with various cardiometabolic complications, including increased cardiovascular morbidity and mortality. We aimed to analyze the difference in serum 25-hydroxyvitamin D (25-OHD) level, prevalence of vitamin D insufficiency and deficiency, and the effect of CPAP treatment on serum 25-OHD levels among adult patients with OSA.

METHODS

We pooled data from 18 observational studies involving 5592 individuals. Baseline parameters that might have contributed to the significant differences observed were also analyzed.

RESULTS

Patients with OSA had significantly lower serum 25-OHD levels (pooled d +  - 0.74 [95% CI: - 1.19 to - 0.28], p < 0.01) and higher prevalence of vitamin D deficiency (pooled log (odds ratio) 0.98 [95% CI: 0.30 to 1.67], p < 0.01) compared to those without OSA. Subgroup analysis demonstrated that these differences were significant only in moderate OSA and severe OSA. Neither age nor BMI nor geographical latitude contributed significantly to the differences observed in serum 25-OHD levels. The use of CPAP did not lead to significant changes in serum 25-OHD levels.

CONCLUSION

Patients with OSA have lower serum 25-OHD levels with a higher prevalence of vitamin D deficiency, regardless of age or BMI, pointing to an independent association between vitamin D and OSA.

Severe Vitamin D Deficiency-A Possible Cause of Resistance to Treatment in Psychiatric Pathology

In the last few years, vitamin D functions have been studied progressively, and along with their main role in regulating calcium homeostasis, the potential function in the nervous system and the link between different psychiatric disorders and vitamin D deficiency have been revealed. The discovery of vitamin D receptors in multiple brain structures, like the hippocampus, led to the hypothesis that vitamin D deficiency could be responsible for treatment resistance in psychiatric diseases. The aim of this study was to analyze the current knowledge in the literature regarding vitamin D deficiency among individuals afflicted with psychiatric disorders and assess the potential therapeutic benefits of vitamin D supplementation. A systematic search was conducted on the PubMed database for articles published in the last five years (2016-2022) in English, focusing on human subjects. Results show that vitamin D deficiency has implications for numerous psychiatric disorders, affecting mood and behavior through its influence on neurotransmitter release, neurotrophic factors, and neuroprotection. It also plays a role in modulating inflammation, which is often elevated in psychiatric disorders. In conclusion, vitamin D deficiency is prevalent and has far-reaching implications for mental health. This review underscores the importance of exploring the therapeutic potential of vitamin D supplementation in individuals with psychiatric disorders and highlights the need for further research in this complex field.

Vitamin D Levels in Patients with Overlap Syndrome, Is It Associated with Disease Severity?

Background: The coexistence of chronic obstructive pulmonary disease (COPD) and obstructive sleep apnea (OSA) has been defined as overlap syndrome (OVS). Recently, a link between OSA, COPD and Vitamin D (Vit D) serum concentration was reported, however, evidence regarding Vit D status in patients with OVS is scarce. The aim of the present study was to evaluate Vit D serum levels and to explore the association of those levels with anthropometric, pulmonary function and sleep parameters in patients with OVS. Methods: Vit D serum levels were measured in patients diagnosed with OVS, as confirmed by overnight polysomnography and pulmonary function testing. Results: A total of 90 patients (79 males and 11 females) were included in the analysis. The patients were divided into three groups matched for age, gender, and BMI: the control group that included 30 patients (27 males and 3 females), the OSA group that included 30 patients (26 males and 4 females), and the OVS group that included 30 patients (26 males and 4 females). Patients with OVS exhibited decreased serum 25(OH)D levels compared with OSA patients and controls (14.5 vs. 18.6 vs. 21.6 ng/mL, p < 0.001). In the OVS group, multiple linear regression analysis identified AHI and FEV1, as predictors of serum 25(OH)D levels (p = 0.041 and p = 0.038, respectively). Conclusions: Lower Vit D levels have been observed in patients with OVS compared with OSA patients and non-apneic controls, indicating an increased risk of hypovitaminosis D in this population which might be associated with disease severity.

Sleep duration as an independent factor associated with vitamin D levels in the EPISONO cohort

STUDY OBJECTIVES

Obstructive sleep apnea and short sleep duration have been separately associated with inadequate serum 25-hydroxyvitamin D [25(OH)D] levels. However, whether these 2 factors may concurrently influence 25(OH)D in the general population is unknown. We hypothesized that both obstructive sleep apnea and short sleep duration would be independently associated with lower concentrations of 25(OH)D in a sex-dependent manner.

METHODS

In this cross-sectional study, 712 individuals, part of the prospective EPISONO cohort (Brazil), underwent polysomnography, answered sleep questionnaires, and had their blood collected for serum 25(OH)D quantification.

RESULTS

Individuals with a sleep duration of < 6 hours had 2-fold increased odds of 25(OH)D < 20 ng/mL compared with those who reported 6 or more hours of sleep, even after adjusting for confounding factors. Subset sex analysis revealed that men with a sleep duration of < 6 hours had 4-fold increased odds of 25(OH)D < 20 ng/mL. In women, short sleep duration was not associated with lower 25(OH)D levels. The presence of obstructive sleep apnea (as classified according to the individual's apnea-hypopnea index) was not independently related to 25(OH)D concentrations in men or women. Sleep parameters, including sleep latency and sleep efficiency, had no association with 25(OH)D < 20 ng/mL.

CONCLUSIONS

Short sleep, but not apnea-hypopnea index, was an independent factor associated with low 25(OH)D serum levels in men, but not in women. Apnea-hypopnea index scores were not associated with 25(OH)D levels in either sex. These results raise the possibility of investigating sex-specific characteristics, such as gonadal hormone regulation, and re-evaluating obstructive events by classifying them in mild, moderate, and severe obstructive sleep apnea.

CITATION

de Oliveira DL, Dokkedal-Silva V, Fernandes GL, Kim LJ, Tufik S, Andersen ML. Sleep duration as an independent factor associated with vitamin D levels in the EPISONO cohort. J Clin Sleep Med. 2021;17(12):2439-2449.

Association of serum 25-hydroxyvitamin D concentration with anthropometric measures in children and adolescents: the CASPIAN-V study

BACKGROUND

Serum 25-hydroxyvitamin D (25(OH)D) concentrations reflect vitamin D status, with deficiency implicated as an underlying factor for many adverse health effects. This study aims to analyze the association between vitamin D status and different anthropometric measures in a large pediatric population.

METHODS

This nationwide cross-sectional study was conducted in 2019 in blood samples obtained from school students of 30 provinces in Iran. Participants were 2596 children and adolescents aged 7-18 years. Weight, height, waist circumference (WC), hip circumference (HC), neck circumference (NC), and wrist circumference (WrC) were measured. Body mass index (BMI) and waist-to-height ratio (W/HtR) were calculated. Serum 25(OH)D concentrations were measured using chemiluminescent immunoassay.

RESULTS

Participants consisted of 55% boys, 71.3% urban inhabitants, with a mean (SD) age of 12.1 (3.0) years. Overall, vitamin D deficiency was documented in 10.6% of participants, insufficiency in 60.4%, and sufficiency in 29% of the population studied. The mean of BMI and WC was higher in the vitamin D deficient than in the vitamin D sufficient group (19.31 kg/m² and 69.24 cm vs. 18.34 kg/m² and 65.73 cm, respectively, P < 0.01). Multivariate linear regression models revealed a significant association of vitamin D insufficiency with WC and W/HtR (P < 0.05). Likewise, in the multivariate regression models, vitamin D deficiency was associated with BMI, WC, and W/HtR (P < 0.05).

CONCLUSION

Our findings on the inverse association between vitamin D status and some anthropometric measures underscore the importance of providing vitamin D by fortification and supplementation programs of vitamin D for the pediatric population.

LEVEL OF EVIDENCE

V.

The Association of Serum 25(OH) Vitamin D Level with Severity of Obstructive Sleep Apnea Syndrome in Patients with Syndrome Z (the Interaction of Obstructive Sleep Apnea with Metabolic Syndrome)

Background: The interaction of obstructive sleep apnea syndrome (OSAS) with metabolic syndrome (MetS) is known as syndrome Z. The aim of this study was to investigate the association of serum vitamin D levels with severity of OSAS in patients with Syndrome Z. Methods: In this retrospective study, 270 patients with MetS and OSAS were included. Demographic data, lifestyle habits, anthropometric measurements, sleep characteristics, polysomnographic indices, and laboratory results were recorded from the patient files. Multivariable logistic regression analyses were performed to determine the associations of serum 25(OH)D3 levels with OSAS. Results: Of the 270 patients, 71.9% were female. The mean age was 46.86 ± 8.46 (33-72) years. Of the participants, 8.2% did not have OSAS (control group), while 30.4% had mild, 28.1% had moderate, and 33.3% had severe OSAS. There were significant differences in gender, waist circumference, hip circumference, waist/hip ratio, neck circumference, body mass index, apnea-hypopnea index, total sleep time, average SpO2 and Epworth sleepiness scale score, oxygen desaturation index, blood glucose, total cholesterol, triglycerides, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, and 25(OH)D3 levels. There was a significant difference in serum 25(OH)D3 level with increasing severities of OSAS (none+mild to moderate+severe OSAS). After adjusting for potential confounding factors in multivariable logistic regression analyses, we found that serum 25(OH)D3 level was significantly associated with the severity of OSAS. Conclusions: Serum 25(OH)D3 level was significantly associated with the severity of OSAS in patients with Syndrome Z. Therefore, patients with MetS and OSAS should be investigated for the presence of vitamin D insufficiency and, if observed, referred for vitamin D treatment.

Study on the Improvement of Behavioral and Cognitive Dysfunction of Children with OSAHS by Vitamin D

Objective

This study is aimed at exploring the role of vitamin D in the treatment of children with OSAHS by comparing the clinical symptoms, serum indicators, and behavioral changes of vitamin D intervention.

Method

Healthy children who were examined physically in Rizhao People's Hospital were selected as the control group, and their sex, age, triglyceride, total cholesterol, high-density lipoprotein, low-density lipoprotein, serum 25-OHD levels, and Conners' parental scale were measured. In addition, children diagnosed as OSAHS in the otolaryngology department of Rizhao People's Hospital were selected as experimental subjects. Their body mass index, triglycerides, total cholesterol, high-density lipoprotein, low-density lipoprotein, serum 25-OHD levels, sleep apnea hypopnea index, minimum oxygen saturation, and Conners' parental scale were measured. The experimental subjects were treated with Rocaltrol intervention therapy (0.25 g/QD) for 4 weeks and reanalyzing their triglycerides, total cholesterol, high-density lipoprotein, low-density lipoprotein, serum 25-OHD levels, sleep apnea hypopnea index, minimum oxygen saturation, and Conners' parental scale.

Result

OSAHS children commonly have the situation of obesity, dyslipidemia, and vitamin D deficiency. Behavioral and cognitive dysfunction is common in OSAHS children. There were no significant changes in body mass index, triglycerides, total cholesterol, high-density lipoprotein, low-density lipoprotein, sleep apnea, hypopnea index, and minimum oxygen saturation for OSAHS children after vitamin D treatment, but the serum 25-OHD level is significantly improved, and children with conduct problems, learning problems, and hyperactivity index decrease.

Conclusion

(1) OSAHS children commonly have the situation of obesity, dyslipidemia, vitamin D deficiency, and behavioral and cognitive impairment. (2) Vitamin D supplementation has no therapeutic effect on obesity and dyslipidemia of OSAHS children, but has obvious protective and improving effects on neuron damage caused by hypoxia. Obstructive sleep apnea syndrome (OSAHS) is a common disease. Patients with OSAHS usually have many clinical features, such as obesity, metabolic syndrome, and cardiovascular disease. The decline of cognitive function and learning ability is one of the serious complications of OSAHS patients [1]. Vitamin D (VitD) deficiency is associated with many diseases. Recent studies have shown that the serum 25-OHD level of OSAHS patients is relatively insufficient and related to the disease severity. However, there are few reports on explaining whether vitamin D supplementation can alleviate the clinical symptoms and improve serum indicators and behavioral and cognitive dysfunction in children with OSAHS.

Vitamin D and Sleep Regulation: Is there a Role for Vitamin D?

BACKGROUND

Vitamin D exerts multiple pleiotropic effects beyond its role in calcium-phosphate metabolism. Growing evidence suggests an association between hypovitaminosis D and sleep disorders, thus increasing the interest in the role of this vitamin in the regulatory mechanisms of the sleep-wake cycle.

OBJECTIVE

The study aimed to explore and summarize the current knowledge about the role of vitamin D in sleep regulation and the impact of vitamin D deficiency on sleep disorders.

METHODS

The main regulatory mechanisms of vitamin D on sleep are explained in this study. The literature was scanned to identify clinical trials and correlation studies showing an association between vitamin D deficiency and sleep disorders.

RESULTS

Vitamin D receptors and the enzymes that control their activation and degradation are expressed in several areas of the brain involved in sleep regulation. Vitamin D is also involved in the pathways of production of Melatonin, the hormone involved in the regulation of human circadian rhythms and sleep. Furthermore, vitamin D can affect sleep indirectly through non-specific pain disorders, correlated with alterations in sleep quality, such as restless legs syndrome and obstructive sleep apnea syndrome.

CONCLUSION

Vitamin D has both a direct and an indirect role in the regulation of sleep. Although vitamin D deficiency has been associated to sleep disorders, there is still scant evidence to concretely support the role of vitamin D supplementation in the prevention or treatment of sleep disturbances; indeed, more intervention studies are needed to better clarify these aspects.

Vitamin D in obesity and obesity-related diseases: an overview

Hypovitaminosis D and obesity represent two pandemic conditions sometimes associated with each other. Although it is known that there is a close relationship between these two health problems, the underlying pathophysiological mechanism has not yet been fully clarified. In fact, on the one hand, obesity per se seems to involve low circulating levels of vitamin D due to low sun exposure, physical activity, and intake of foods rich in vitamin D, volumetric dilution and sequestration in the adipose tissue. Conversely, since preadipocytes and adipocytes express the receptors and are involved in the metabolism of vitamin D it would seem that low levels of this vitamin may be involved in adipogenesis and therefore in the development of obesity. This connection is extremely important when considering obesity-related diseases. In fact, low vitamin D levels and severe obesity are significantly associated with some cardio-metabolic risk factors, including high Body Mass Index, waist circumference, blood pressure, impaired lipid and glycemic profile and insulin resistance, as they would seem associated with worse cardiovascular outcomes and higher cancer incidence and mortality. Therefore, the purpose of this review was to examine the recent evidence linking low vitamin D status, obesity and obesity-related diseases, highlighting the scientific achievements and the gaps to be filled with further investigations.

The association between serum vitamin D and obstructive sleep apnea: an updated meta-analysis

BACKGROUND

The objective was to determine whether OSA patients have a low serum vitamin D level by systematic review and meta-analysis.

METHODS

This study searched the following electronic bibliographic databases: Embase, Medline, Web of Science, PubMed, VIP, Wanfang, CNKI and SinoMed. All data were searched between January 2000 and August 2020. The quality of the included studies was estimated by two researchers according to the Newcastle-Ottawa Scale and Agency for Healthcare Research and Quality. All qualified studies and statistical analyses were conducted using RevMan 5.2.

RESULTS

Twenty-nine eligible studies compromising 6717 participants met the inclusion criteria of the meta-analysis. The results revealed that the serum 25(OH)D level was significantly lower in OSA patients than the controls. According to the severity of the disease, subgroup analysis was performed; the results demonstrated that the serum 25(OH)D level was not decreased in mild OSA patients compared with the controls, while the serum 25(OH)D level in moderate and severe OSA patients was lower than that in the controls. Furthermore, based on ethnicity, BMI, PSG type, study quality and latitude, the subjects were divided into different subgroups for meta-analysis. The results revealed that the serum 25(OH)D level in all OSA subgroups was decreased compared with that in the control group.

CONCLUSIONS

The present meta-analysis shows that the serum vitamin D level was different between OSA patients and healthy people. OSA patients could have a low serum vitamin D level.

A meta-analysis: Does vitamin D play a promising role in sleep disorders?

BACKGROUND

Sleep disorders, one of the most common problems in the general population, have been related to a series of harmful health consequences. Vitamin D appears to be associated with sleep disorders. However, the difference in vitamin D levels between sleep disorder subjects and people without a sleep disorder is unclear. Simultaneously, the influence of vitamin D replenishment on sleep disorders remains controversial.

METHODS

PubMed, MEDLINE, Web of Science, and Cochrane Library were searched for literatures published until October 2019. Using a random effects model, a meta-analysis was conducted to calculate the standard mean difference to evaluate the difference in vitamin D concentrations between sleep disorder subjects and normal people and the efficacy of vitamin D supplementation on sleep disorders.

RESULTS

Our study found that the serum vitamin D levels in the sleep disorder subjects were lower than that in the normal people (SMD = -0.75 ng/ml, 95% CI = -0.93, -0.57 ng/ml). Moreover, the Pittsburgh Sleep Quality Index (PSQI)in the subjects with vitamin D supplementation was lower than that in the controls (SMD = -0.45, 95% CI = -0.76, -0.13).

CONCLUSIONS

Vitamin D could play a promising role in sleep disorders. More data are required to confirm the efficacy of vitamin D supplementation for improving sleep disorders.

Serum vitamin D levels in patients with obstructive sleep apnea syndrome and level changes after continuous positive airway pressure therapy

PURPOSE

Patients with obstructive sleep apnea syndrome (OSAS) have been found to exhibit lower serum vitamin D levels, even when the control groups are matched for confounding conditions. However, contradictory studies are also present. This study aimed to compare serum 25-hydroxyvitamin D (25(OH)D) levels between adult patients with OSAS and non-apneic controls and to evaluate the changes in 25(OH)D levels after 3 and 12 months of continuous positive airway pressure (CPAP) therapy.

METHODS

The study was comprised of 30 patients with OSAS and 30 controls. Serum 25(OH)D levels were determined at baseline and after 3 and 12 months of CPAP therapy in all patients with OSAS. For analysis, patients with OSAS were divided into subgroups by adherence, with adherence defined as CPAP usage for > 4 h per night on at least 70% of nights.

RESULTS

The 25(OH)D levels were not significantly different between OSAS and control groups at baseline. 25(OH)D levels did not change after 3 and 12 months of CPAP therapy. Patients who were CPAP-adherent showed less reduction in 25(OH)D levels compared with non-adherent ones (21.18 ± 9.3 vs. 12.13 ± 3.8 ng/mL, p = 0.022) after 1 year. The 25(OH)D levels were significantly correlated with higher daily CPAP usage at 3 and 12 months. Mean daily CPAP usage was a significant predictor of serum 25(OH)D levels at 12 months.

CONCLUSIONS

Patients with OSAS who demonstrated good CPAP adherence showed significantly higher 25(OH)D levels after 1 year compared with those not adequately using CPAP. Long-term good CPAP adherence and highly daily CPAP usage positively affected 25(OH)D levels in patients with OSAS.

25-hydroxyvitamin D levels in patients with obstructive sleep apnea and continuous positive airway pressure treatment: a brief review

The aim of the present study is to summarize the information available, to time, regarding the relationship between obstructive sleep apnea (OSA) and vitamin-D (vD) levels. Moreover, the association between vD deficiency and OSA severity will also be examined. At the end of the present study the possible advantageous effect of CPAP on vD-levels will be summarized. Extensive literature search was conducted in PubMed, Scopus, The Cochrane Library and Embase database. 13 articles were found concerning OSA and vD, of which 2 articles included treatment with a CPAP. Patients with OSA exhibit low levels of vD in the blood serum, and women present an even lower mean value than men. Lack of VD in blood serum seems to be related to the severity of the OSA syndrome, and to the short duration of sleep. OSA patients with concurrent metabolic syndrome exhibit lower serum vD-levels, as compared with those without metabolic syndrome. Long-term continuous positive airway pressure treatment (CPAP) treatment can increase vD-levels in male OSA patients while no change is observed in women. OSA patients demonstrate lower levels of vD in multiple studies. The severity of the OSA may be associated with vD-levels and deficiency, however more studies are needed to assess that relationship due to contradictions in current bibliography. CPAP can increase vD-levels in male patients. The relation between vD and OSA and/or CPAP is important but recent; therefore further research is needed about the exact relationship to be clarified. Also, the effect of gender hormones on vD regulation in OSA patients should be further investigated.

Vitamin D deficiency in patients evaluated for obstructive sleep apnea: is it associated with disease severity?

PURPOSE

The aim of the present study was to assess vitamin D levels in a large cohort of OSA patients and to investigate possible correlations with clinical and polysomnographic parameters.

METHODS

In this cross-sectional study, 685 consecutive patients underwent type 1 polysomnography (PSG) for OSA diagnosis. They were grouped according to apnea-hypopnea index (AHI) as mild, moderate, and severe. Patients with AHI < 5 served as controls. Demographic, PSG data, and serum levels of vitamin D were measured and compared between groups.

RESULTS

OSA was diagnosed in 617 of the patients (90%). Of those, 94 (15%) had mild OSA, 150 (24%) moderate OSA, and 373 (61%) severe OSA. The risk of vitamin D deficiency (< 20 ng/mL) was observed in 38% of the cohort. OSA patients had lower vitamin D levels compared to controls (23 ng/mL vs 26 ng/mL, p = 0.006). The lowest levels of vitamin D [mean 21] (p < 0.001 among all groups) and the higher prevalence for vitamin D deficiency (45%) were observed in severe OSA patients. After multiparametric adjustments for age, gender, obesity, and comorbidities, severe OSA showed significant independent associations with the risk of vitamin D deficiency [OR (95% CI) 2.002 (1.049-3.819), p = 0.035].

CONCLUSIONS

A large proportion of patients referred for OSA evaluation had vitamin D deficiency, which was independently associated with severe OSA. However, further research is needed in order to determine the role of vitamin D in OSA patients.

Sleep duration is associated with vitamin D deficiency in older women living in Macao, China: A pilot cross-sectional study

Chinese women are known to have both a high prevalence of metabolic syndrome (MetS) and vitamin D deficiency (serum 25-hydroxyvitamin D (25OHD) <50 nmol/l). Associations between sleep duration and circulating 25OHD have recently been reported but, to our knowledge, these associations have not been studied in older Chinese populations. We thus investigated whether sleep duration was associated with vitamin D status in a population from Macao, China, and whether sleep duration modified the association between MetS and vitamin D deficiency. In 207 older (>55 years) Macanese, anthropometry, blood samples and validated questionnaires, including sleep duration and cardiovascular risk factors, were simultaneously collected. On multivariable categorical analyses, those women, not men, who had short sleep duration (≤6 hours (h)) were at a 2-fold risk for vitamin D deficiency (both <50 nmol/L and <37 nmol/L; OR = 1.94, 95%CI 1.29–2.92; OR = 2.05, 95%CI 1.06–3.98, respectively) and those who had longer sleep duration (>8 h) were 3-fold more likely to have vitamin D deficiency (OR = 3.07, 95%CI 1.47–6.39; OR = 2.75, 95%CI 1.08–7.00, respectively) compared to those with normal sleep duration (6–8 h). Both women and men with MetS were 2-fold more likely to have vitamin D deficiency (women: OR = 2.04, 95%CI 1.31–3.17; OR = 2.15, 95%CI 1.11–4.17, respectively; men: OR = 2.01, 95%CI 1.23–3.28; OR = 2.04, 95%CI 1.00–4.29, respectively). Moreover, women with both short sleep duration and MetS had an increased risk of vitamin D deficiency (OR = 3.26, 95%CI 1.10–9.64). These associations were not found in those with longer sleep. Men with longer sleep and MetS had a 5-fold risk of vitamin D deficiency (OR = 5.22; 95%CI 2.70–10.12). This association was non-significant for men with shorter sleep. We conclude that both short and long sleep duration were associated with vitamin D deficiency in older Chinese women. Further research is needed in larger cohorts or with intervention studies to further examine the associations between reduced sleep, metabolic syndrome and vitamin D deficiency.

The Relationship of Serum 25-Hydroxyvitamin-D Level with Severity of Obstructive Sleep Apnea in Patients with Type 2 Diabetes Mellitus

OBJECTIVE

To explore the association of serum vitamin-D levels with the severity of obstructive sleep apnea (OSA) in patients with type 2 diabetes mellitus (T2DM).

METHODS

A cross-sectional study of 136 patients with T2DM who underwent overnight polysomnography (PSG) tests and serum 25-hydroxyvitamin-D3 (25(OH)D3) level detections was conducted. Multivariable linear regression and logistic regression analyses were performed to determine the associations of serum 25(OH)D3 levels with apnea-hypopnea index (AHI) and obstructive sleep apnea (OSA).

RESULTS

The prevalence rates of OSA were 84.4% for male and 65.2% for female patients, respectively (p = 0.011). With increasing severities of OSA categories (none, mild, moderate and severe), patients were more likely to be male and obese, but there was no significant difference in serum 25(OH)D3 level ((mean ± standard deviation) 21.8 ± 8.8, 27.7 ± 14.6, 24.2 ± 9.8 and 26.8 ± 6.2 ng/mL, respectively, p=0.086). Serum 25(OH)D3 level was not significantly correlated with AHI (log-transformed), with the correlation coefficient of 0.133 (p=0.124). With adjustment for potential confounding factors, multivariable linear regression and logistic regression analyses showed that serum 25(OH)D3 level was not significantly associated with either AHI (log-transformed) or the risk of OSA, with the standardized regression coefficient (95% confidence interval (CI)) of 0.098 (-0.004-0.014, p=0.252) and the adjusted odds ratio (95% CI) of 1.055 (0.991-1.124, p=0.095), respectively.

CONCLUSION

Serum 25(OH)D3 level was not significantly associated with either AHI or the risk of OSA in patients with T2DM.

25-Hydroxyvitamin D status, light exposure and sleep quality in UK dwelling South Asian and Caucasian postmenopausal women

There is a lack of research into 25-hydroxyvitamin D (25(OH)D) status, light exposure and sleep patterns in South Asian populations. In addition, results of research studies are conflicting as to whether there is an association between 25(OH)D status and sleep quality. We investigated 25(OH)D status, self-reported and actigraphic sleep quality in n = 35 UK dwelling postmenopausal women (n = 13 South Asians, n = 22 Caucasians), who kept daily sleep diaries and wore wrist-worn actiwatch (AWL-L) devices for 14 days. A subset of n = 27 women (n = 11 South Asian and n = 16 Caucasian) also wore a neck-worn AWL-L device to measure their light exposure. For 25(OH)D concentration, South Asians had a median ± IQR of 43.8 ± 28.2 nmol/L, which was significantly lower than Caucasians (68.7 ± 37.4 nmol/L)(P = 0.001). Similarly, there was a higher sleep fragmentation in the South Asians (mean ± SD 36.9 ± 8.9) compared with the Caucasians (24.7 ± 7.1)(P = 0.002). Non-parametric circadian rhythm analysis of rest/activity patterns showed a higher night-time activity (L5) (22.6 ± 14.0 vs. 10.5 ± 4.4; P = 0.0008) and lower relative amplitude (0.85 ± 0.07 vs. 0.94 ± 0.02; P < 0.0001) in the South Asian compared with the Caucasian women. More South Asians (50%) met the criteria for sleep disorders (PSQI score >5) than did Caucasians (27%) (P = 0.001, Fishers Exact Test). However, there was no association between 25(OH)D concentration and any sleep parameter measured (P > 0.05) in either ethnic group. South Asians spent significantly less time in illuminance levels over 200 lx (P = 0.009) than did Caucasians. Overall, our results show that postmenopausal South Asian women have lower 25(OH)D concentration than Caucasian women. They also have higher sleep fragmentation, as well as a lower light exposure across the day. This may have detrimental implications for their general health and further research into sleep quality and light exposure in the South Asian ethnic group is warranted.

Serum vitamin D status does not correlate with the severity of obstructive sleep apnea in male adults: A controlled study design with minimized factors influencing serum vitamin D levels

Observational studies performed in homogeneous groups to objectively investigate the cause and effect relationship between vitamin D deficiency and sleep disorders are scarce. In this study, it was aimed to analyze the relationship between the severity of OSAS and vitamin-D levels among the participants whose features affecting serum vit-D levels were minimised. Serum 25-OH vitamin-D levels in 121 OSAS Male patients diagnosed by polysomnography without any systemic disease or vitamin-D supplement that may effect the vitamin-D metabolism were measured. The study was conducted in winter (latitude: 41°). Anthropometric measures and biochemical tests were also performed. The distribution of vitamin-D levels was determined as severe deficiency, deficiency, insufficiency and sufficiency. Apnea-hypopne index (AHI) < 5 was considered as a control group. Patients were categorized into four groups according to AHI as control, mild, moderate and severe. The groups were similar in terms of age, BMI, lipid profile, serum calcium, anthropometric measures and smoking. There was no significant difference in the distribution of vitamin-D levels between the patient and control groups and also within OSAS subgroups (p = 0.57, p = 0.86, respectively). Odds ratio to have OSAS in patients with vitamin-D deficiency was found as 0.745 (95 %CI: 0.33-1.7). Multinominal regression analysis showed no significant relationship between the OSAS severity and the extent of vitamin-D status. Correlation analysis showed no significant relationship between vitamin-D and AHI (r = 0.017, p = 0.877). Vitamin-D status does not alter the severity of OSAS. Vitamin-D deficiency might be the result of lifestyle changes due to OSAS rather than a cause.

Vitamin D supplementation and body fat mass: a systematic review and meta-analysis

Studies have indicated that 25-hydroxyvitamin D (25(OH)D) level in obese is lower than normal weight subjects; however, results of studies that investigated relationship between 25(OH)D and fat mass are inconsistent. In addition, several randomized clinical trials (RCTs) have studied the influence of cholecalciferol supplement on percentage fat mass (PFM) but their results are conflicting. The objectives were to investigate the association between vitamin D3 and PFM pooling together observational studies and RCTs. PubMed/MEDLINE, Cochrane, and Scopus were comprehensively searched from inception to September 2016. The Fisher's Z (SE) of correlation coefficient and mean (SD) of changes in PFM from baseline were used to perform meta-analysis in observational studies and RCTs, respectively. To determine potential source of heterogeneity, subgroup and meta-regression analyses were conducted. Pooling correlation coefficients showed an inverse association between PFM (Fisher's Z: - 0.24, 95% CI: - 0.30 to -0 .18) and FM (Fisher's Z: - 0.32, 95% CI: - 0.43 to - 0.22) and 25(OH)D. Subgroup analysis revealed continent but not gender influence on the effect size. Meta-regression analysis indicated that age, latitude, and longitude are not sources of heterogeneity. Combining trials showed vitamin D3 supplementation had a mild but insignificant effect on PFM (- 0.31%, 95% CI: - 1.07 to 0.44). Subgroup analyses indicated that type of cholecalciferol and treatment regimens explain source of heterogeneity. Age, baseline body mass index, dose of cholecalciferol, length of study, female (%), and baseline 25(OH)D are not source of heterogeneity. In conclusion, our results state that 25(OH)D level is inversely correlated with PFM but cholecalciferol supplementation had no effect on PFM.

Dietary nitrate improved exercise capacity in COPD but not blood pressure or pulmonary function: a 2 week, double-blind randomised, placebo-controlled crossover trial

Dietary nitrate may improve exercise tolerance in some healthy and clinical populations. Existing data regarding dietary nitrate in COPD is inconsistent. We conducted a 14d double-blind, randomised, placebo-controlled, crossover trial of daily nitrate-rich beetroot juice (BRJ; 12.9 mmol) versus nitrate-depleted BRJ (PL; 0.5 mmol). At baseline and after each condition, we assessed functional capacity (incremental shuttle walk test; ISWT), ambulatory blood pressure, pulmonary function, quality of life as well as exhaled nitric oxide (eNO), and plasma nitrate/nitrite (NOx). Eight subjects with COPD completed the trial. BRJ supplementation was associated with significantly increased NOx (p < .05) and a 14.6% increase in ISWT distance (+56 m, p = .00004) as well as a trend towards increased eNO compared to PL. There was no other differences. Dietary nitrate appears to have ergogenic effect in subjects with mild-moderate COPD. This effect does not appear to be related to altering blood pressure or pulmonary function.

The role of vitamin D in obstructive sleep apnoea syndrome

Obstructive sleep apnoea syndrome (OSAS) is a common disorder of multifactorial pathogenesis and is associated with obesity, diabetes and cardiovascular disease. Vitamin D is a fat-soluble vitamin with an important function in calcium absorption and homeostasis, which is also implicated in several nonskeletal conditions. The prevalence of vitamin D deficiency is increasing worldwide and is associated with similar metabolic disturbances to OSAS. Moreover, recent data suggest that in OSAS patients serum levels of vitamin D are lower compared with non-apnoeic subjects. However, the mechanisms linking vitamin D deficiency and OSAS are not completely understood and several hypotheses have been advanced. To date, a limited number of studies have assessed the association between lower serum concentrations of vitamin D and OSAS, and have reported inconsistent results. Similarly, contradictory results have been produced by studies which evaluated the effect of continuous positive airway pressure treatment on serum vitamin D levels. The aim of this review is to summarise current knowledge on the association between OSAS and vitamin D levels.

Due to multiple confounding factors, vitamin D deficiency is common among sleep apnoea patients; thus, screening should be performed when clinically indicatedhttp://ow.ly/L3ow30krmol

Less than 7 hours of sleep per night is associated with transitioning to systemic lupus erythematosus

Background The role of sleep in the etiology of systemic lupus erythematosus (SLE) has not been well studied. We examined whether sleep duration was associated with subsequent transitioning to SLE in individuals at risk for SLE. Methods Four hundred and thirty-six relatives of SLE patients who did not have SLE themselves at baseline were evaluated again an average of 6.3 (± 3.9) years later. Fifty-six individuals transitioned to SLE (≥ 4 cumulative American College of Rheumatology (ACR) criteria). Sleep duration, medication use and medical history were assessed by questionnaire; ACR criteria were confirmed by medical record review. Vitamin D was measured by ELISA. Generalized estimating equations, accounting for correlation within families, assessed associations between baseline sleep and the outcome of transitioning to SLE. Results Reporting sleeping less than 7 hours per night at baseline was more common in those who subsequently transitioned than those who did not transition to SLE (55% versus 32%, p = 0.0005; OR: 2.8, 95% CI 1.6-4.9). Those who transitioned to SLE were more likely to sleep less than 7 hours per night than those who did not transition to SLE adjusting for age, sex and race (OR: 2.8, 95% CI 1.6-5.1). This association remained after individual adjustment for conditions and early symptoms that could affect sleep, including prednisone use, vitamin D deficiency and number of ACR criteria (OR: 2.0, 95% CI 1.1-4.2). Conclusion Lack of sleep may be associated with transitioning to SLE, independent of early clinical manifestations of SLE that may influence sleep duration. Further evaluation of sleeping patterns and biomarkers in at-risk individuals is warranted.

Metabolic Syndrome and Vitamin D Levels in Patients with Obstructive Sleep Apnea Syndrome

BACKGROUND

Numerous studies have indicated that obstructive sleep apnea syndrome (OSAS), may contribute to the development of metabolic syndrome (MetS) and diabetes. Moreover, OSAS has been associated with lowered vitamin D (Vit D) levels, but reports are inconclusive. Aim of the study was to compare Vit D levels according to the presence of MetS and its components in OSAS patients.

METHODS

The presence of MetS was evaluated and serum 25-hydroxy vitamin D [25(OH)D] levels were measured in consecutive newly diagnosed, by polysomnography, subjects with OSAS.

RESULTS

A total of 107 subjects (88 men) with OSAS were included in the study. Patients were divided into group A (OSAS with MetS group: 55 subjects) and group B (OSAS without MetS: 52 subjects). There were no differences between the two groups in terms of age, body mass index, and sleep parameters. Patients in group A exhibited higher levels of daytime sleepiness, as expressed by Epworth Sleepiness Scale score (12 ± 5.5 vs. 9.3 ± 4.8 for groups A vs. B, p = 0.008). Serum 25(OH)D levels were significantly decreased in group A, as compared with group B (18 ± 8.6 ng/mL vs. 23.9 ± 14.1 ng/mL, respectively, p = 0.012). Group A was then subdivided in two smaller groups, according to patients' metabolic index: OSAS patients with metabolic score = 3 and OSAS patients with metabolic score >3. Serum 25(OH)D levels were higher in OSAS patients with metabolic score = 3 compared with OSAS patients with metabolic score >3 (19.8 ± 8.9 ng/mL vs. 15.1 ± 7.3 ng/mL respectively, p = 0.038).

CONCLUSIONS

OSAS patients with concurrent MetS exhibit lower serum Vit D levels, as compared with those without MetS.

Vitamin D and respiratory health in the Busselton Healthy Ageing Study

BACKGROUND AND OBJECTIVE

The relationship between vitamin D and respiratory disease was examined by cross-sectional analysis of a large community-based sample.

METHODS

Serum 25-hydroxyvitamin D (25OHD) and history of respiratory disease, symptoms (recorded by questionnaire) and spirometry were measured in 5011 adults aged 45-69 years. Adjustments were made for age, sex, season and smoking (Model A), plus body mass index (BMI) and physical activity level (Model B), plus history of chronic diseases (Model C).

RESULTS

Mean (SD) age was 58 (SD 6) years with 45% males, 10% current smokers and 12% taking vitamin D supplements. The prevalence of 25OHD level <50 nmol/L was 8.0%. In all the three models, 25OHD <50 nmol/L was significantly associated with asthma (Model C: odds ratio (OR): 1.32; 95% CI: 1.00, 1.73), bronchitis (1.54; 1.17, 2.01), wheeze (1.37; 1.10, 1.71) and chest tightness (1.42; 1.10, 1.83). Participants with vitamin D level > 100 nmol/L had higher forced vital capacity (FVC) in all the three models (1.17% higher, compared with the 50-100 nmol/L group in Model C).

CONCLUSION

Low levels of serum 25OHD were independently associated with asthma, bronchitis, wheeze and chest tightness after three levels of adjustment for potential confounders. Higher vitamin D levels were associated with higher levels of lung function.

Interactions between and Shared Molecular Mechanisms of Diabetic Peripheral Neuropathy and Obstructive Sleep Apnea in Type 2 Diabetes Patients

Type 2 diabetes (T2D) accounts for about 90% of all diabetes patients and incurs a heavy global public health burden. Up to 50% of T2D patients will eventually develop neuropathy as T2D progresses. Diabetic peripheral neuropathy (DPN) is a common diabetic complication and one of the main causes of increased morbidity and mortality of T2D patients. Obstructive sleep apnea (OSA) affects over 15% of the general population and is associated with a higher prevalence of T2D. Growing evidence also indicates that OSA is highly prevalent in T2D patients probably due to diabetic peripheral neuropathy. However, the interrelations among diabetic peripheral neuropathy, OSA, and T2D hitherto have not been clearly elucidated. Numerous molecular mechanisms have been documented that underlie diabetic peripheral neuropathy and OSA, including oxidative stress, inflammation, endothelin-1, vascular endothelial growth factor (VEGF), accumulation of advanced glycation end products, protein kinase C (PKC) signaling, poly ADP ribose polymerase (PARP), nitrosative stress, plasminogen activator inhibitor-1, and vitamin D deficiency. In this review, we seek to illuminate the relationships among T2D, diabetic peripheral neuropathy, and OSA and how they interact with one another. In addition, we summarize and explain the shared molecular mechanisms involved in diabetic peripheral neuropathy and OSA for further mechanistic investigations and novel therapeutic strategies for attenuating and preventing the development and progression of diabetic peripheral neuropathy and OSA in T2D.

Changes of vitamin D levels and bone turnover markers after CPAP therapy: a randomized sham-controlled trial

The aim was to investigate whether continuous positive airway pressure treatment could modulate serum vitamin D (25-hydroxyvitamin D) and bone turnover markers (collagen-type 1 cross-linked C-telopeptide, osteocalcin and N-terminal propeptide of type 1 collagen) in secondary analysis from a randomized controlled trial. Sixty-five continuous positive airway pressure-naïve male patients with obstructive sleep apnea (age = 49 ± 12 years, apnea-hypopnea index = 39.9 ± 17.7 events h^-1 , body mass index = 31.3 ± 5.2 kg m^-2 ) were randomized to receive either real (n = 34) or sham (n = 31) continuous positive airway pressure for 12 weeks. At 12 weeks, all participants received real continuous positive airway pressure for an additional 12 weeks. After 12 weeks of continuous positive airway pressure (real versus sham), there were no between-group differences for any of the main outcomes [Δ25-hydroxyvitamin D: -0.80 ± 5.28 ng mL^-1 (mean ± SE) versus 3.08 ± 3.66 ng mL^-1 , P = 0.42; Δcollagen-type 1 cross-linked C-telopeptide: 0.011 ± 0.014 ng mL^-1 versus -0.004 ± 0.009 ng mL^-1 , P = 0.48; Δosteocalcin: 1.13 ± 1.12 ng mL^-1 versus 0.46 ± 0.75 ng mL^-1 , P = 0.80; ΔN-terminal propeptide of type 1 collagen: 2.07 ± 3.05 μg L^-1 versus -1.05 ± 2.13 μg L^-1 , P = 0.48]. There were no further differences in subgroup analyses (continuous positive airway pressure-compliant patients, patients with severe obstructive sleep apnea or sleepy patients). However, after 24 weeks irrespective of initial randomization, vitamin D increased in patients with severe obstructive sleep apnea (9.56 ± 5.51 ng mL^-1 , P = 0.045) and in sleepy patients (14.0 ± 4.69 ng mL^-1 , P = 0.007). Also, there was a significant increase in osteocalcin at 24 weeks (3.27 ± 1.06 ng mL^-1 , P = 0.01) in compliant patients. We conclude that 12 weeks of continuous positive airway pressure did not modulate vitamin D or modulate any of the bone turnover markers compared with sham. However, it is plausible that continuous positive airway pressure may have late beneficial effects on vitamin D levels and bone turnover markers in selected groups of patients with obstructive sleep apnea.

Obstructive sleep apnea and objective short sleep duration are independently associated with the risk of serum vitamin D deficiency

BACKGROUND

Studies demonstrate an association between vitamin D (25(OH)D) deficiency and sleep disturbances, such as obstructive sleep apnea (OSA) and short sleep duration. However, to date, no studies have concurrently and objectively evaluated the effect of these factors on 25(OH)D.

OBJECTIVES

To evaluate whether OSA and objective short sleep duration are independently associated with reduced 25(OH)D in an adult population sample.

METHODS

A cross-sectional study included 657 individuals from the city of Sao Paulo, Brazil, as part of the ERA project. Participants fulfilled questionnaires and underwent clinical evaluation, polysomnography and blood sample collection for 25(OH)D quantification. OSA was classified into three categories (mild, moderate and severe). The risk of 25(OH)D deficiency was considered as levels<30 ng/mL. Short sleep duration was defined as total sleep time<6 hours.

RESULTS

The risk of 25(OH)D deficiency was observed in 59.5% of the sample, affecting more individuals of the female gender, obese, with African American ethnicity, and those that were smokers, sedentary and presented hypertension and diabetes. In the final logistic model adjusted for age, gender, ethnicity, obesity, smoking, hypertension, diabetes, sedentary lifestyle, seasonality and creatinine serum levels, both OSA and short sleep duration showed significant independent associations with the risk of 25(OH)D deficiency (moderate OSA: OR for 25(OH)D<30 = 2.21, 95% CI: 1.35-3.64, p<0.01; severe OSA: OR for 25(OH)D<30 = 1.78, 95% CI: 1.06-3.00, p = 0.03; short sleep duration: OR for 25(OH)D<30 = 1.61, 95% CI: 1.15-2.26, p = 0.01). After a subgroup analysis, similar results were observed only in participants ≥50 years.

CONCLUSION

OSA and short sleep duration are independently associated with the risk of 25(OH)D deficiency in an adult population. Age-related changes in vitamin D metabolism and the frequency of sleep disorders may be involved in these associations. Future studies exploring whether 25(OH)D levels may modulate OSA and sleep curtailment-related outcomes are needed.

The interfaces between vitamin D, sleep and pain

The role of vitamin D in osteomineral metabolism is well known. Several studies have suggested its action on different biological mechanisms, such as nociceptive sensitivity and sleep-wake cycle modulation. Sleep is an important biological process regulated by different regions of the central nervous system, mainly the hypothalamus, in combination with several neurotransmitters. Pain, which can be classified as nociceptive, neuropathic and psychological, is regulated by both the central and peripheral nervous systems. In the peripheral nervous system, the immune system participates in the inflammatory process that contributes to hyperalgesia. Sleep deprivation is an important condition related to hyperalgesia, and recently it has also been associated with vitamin D. Poor sleep efficiency and sleep disorders have been shown to have an important role in hyperalgesia, and be associated with different vitamin D values. Vitamin D has been inversely correlated with painful manifestations, such as fibromyalgia and rheumatic diseases. Studies have demonstrated a possible action of vitamin D in the regulatory mechanisms of both sleep and pain. The supplementation of vitamin D associated with good sleep hygiene may have a therapeutic role, not only in sleep disorders but also in the prevention and treatment of chronic pain conditions.

Serum Klotho, vitamin D, and homocysteine in combination predict the outcomes of Chinese patients with multiple system atrophy

AIMS

Neuroinflammation contributed to the pathogenesis of multiple system atrophy (MSA). We aimed to detect the correlation between inflammatory mediators, such as Klotho (Klt), vitamin D (25(OH)D) and homocysteine (Hcy), and disease severity among MSA patients.

METHODS

A total of 53 MSA patients, 65 PD patients, and 62 normal subjects were recruited in our cross-sectional study. Serum Klotho (Klt), vitamin D (25(OH)D), and homocysteine (Hcy) levels were measured. Several scales were undertaken to assess the motor/nonmotor function and cognitive impairment of MSA.

RESULTS

Decreased Serum Klt and 25(OH)D levels and increased Hcy levels were found in patients with MSA, compared with healthy controls. These results were more pronounced in male patients. The three biomarkers also displayed differences between MSA and PD subgroups based on genders. Interestingly, Klt, 25(OH)D and Hcy levels associated with cognition impairment, motor dysfunction, mood/cardiovascular disorder among MSA patients. In addition, the combination of Klt, 25(OH)D and Hcy had a better diagnostic ability for distinguishing MSA patients from healthy subjects, as well as distinguishing male MSA patients from male PD patients.

CONCLUSION

This study suggested that Klt, 25(OH)D and Hcy levels could be a potential predictor for MSA severity evaluation.

Vitamin D Deficiency in Patients Referred for Evaluation of Obstructive Sleep Apnea

STUDY OBJECTIVES

A recent study reported an association between obstructive sleep apnea (OSA) and low vitamin D levels. In this study, we measured vitamin D levels in patients referred for evaluation of suspected OSA and sought to identify associated risk factors for vitamin D deficiency. Our objective was to determine whether evaluations of patients with suspected OSA should include routine screening for vitamin D deficiency.

METHODS

Using a cross-sectional study design, we measured vitamin D levels in consecutively enrolled patients referred for an OSA evaluation to Dr. Lutfi Kirdar Kartal Training and Research Hospital in Istanbul, Turkey. We conducted full-night polysomnography and compared vitamin D levels both between patients with OSA and patients without OSA and across the various severity levels of OSA. We evaluated the association between vitamin D levels and various clinical and demographic characteristics, including the apnea-hypopnea index and body mass index.

RESULTS

From April 2014 to June 2015, 195 patients were referred for OSA evaluation. Of these, 181 patients (93%) consented to participate and underwent full polysomnography and measurement of vitamin D levels. The mean ± standard deviation age was 49 ± 12 years and body mass index of 31 ± 6 kg/m². Polysomnography led to the diagnosis of OSA in 162 of the patients (89.5%): 52 (32%) were categorized as having mild OSA, 38 (23.5%) as having moderate OSA, and 72 (44.5%) as having severe OSA. Vitamin D level was 15.5 ± 11.6 ng/mL (95% confidence interval; 13-17 ng/mL) and 134 patients (74%) met the criterion for vitamin D deficiency (< 20 ng/mL). Sex, vitamin D levels, and percentage of patients with vitamin D deficiency were similar in patients with and without OSA (P > .05). Vitamin D levels were similar across OSA severity categories (P = .68). We found no association between vitamin D levels and the apnea-hypopnea index or body mass index.

CONCLUSION

A large proportion of patients referred for OSA evaluation had vitamin D deficiency. Vitamin D levels did not differ by OSA diagnosis status or severity. Patients referred for polysomnography should undergo routine screening for vitamin D deficiency as well as clinically indicated treatment to prevent associated comorbidities.

Vitamin D Improves Selected Metabolic Parameters but Not Neuropsychological or Quality of Life Indices in OSA: A Pilot Study

STUDY OBJECTIVES

Our group and others have reported a high rate of vitamin D deficiency in obstructive sleep apnea (OSA), where vitamin D levels (25(OH) D) correlate negatively with OSA severity and some of its associated metabolic alterations. Data regarding vitamin D supplementation in OSA are lacking. We wanted to evaluate the effect of vitamin D₃ supplementation on OSA symptoms and metabolic parameters.

METHODS

We conducted a pilot, double-blind, randomized, placebo-controlled trial of daily supplementation with 4,000 IU vitamin D₃ (D3) or placebo (PL). We studied 19 Caucasian adults (14 male, mean age 55 y, mean body mass index [BMI] 30.4 kg/m²) with OSA. Fifteen patients were stable on continuous positive airways pressure (CPAP) therapy, whereas four were CPAP naïve. Assessments were completed at baseline and after 15 weeks of supplementation. Outcomes included sleepiness (Epworth Sleepiness Scale), quality of life (Sleep Apnea Quality of Life Inventory), fatigue (fatigue severity scale) and neuropsychological function (trail making test and Connor's Continuous Performance Test II). In addition, we assessed biochemical indices of vitamin D status (25(OH)D, calcium), inflammation (high sensitivity C-reactive protein, and lipoprotein-associated phospholipase A2), lipids (total cholesterol [low-density and high-density lipoprotein]) and glycemic indices (fasting glucose, oral glucose tolerance test).

RESULTS

There was no change in BMI, medication, or CPAP usage. Although there was no change in neuropsychological or quality of life indices, we observed a significant increase in 25(OH)D (p = 0.00001) and significant decreases in both low-density lipoprotein (p = 0.04) and lipoprotein-associated phospholipase A2 (p = 0.037) as well as trends toward decreased fasting glucose (p = 0.09) and increased high-density lipoprotein (p = 0.07) in the D₃ group compared to PL.

CONCLUSIONS

Vitamin D₃ supplementation increased vitamin D levels and decreased metabolic markers compared to placebo. Larger trials are required.

Vitamin D deficiency and interleukin-17 relationship in severe obstructive sleep apnea-hypopnea syndrome

PURPOSE

We aimed to assess Vitamin D (VD) abnormalities in patients with severe obstructive sleep apnea-hypopnea syndrome (OSAHS), to study its association with clinical and polygraphic data, and to correlate VD levels with interleukin-17 (IL-17).

METHODS

Ninety-two patients with severe OSAHS were consecutively enrolled between September 2014 and February 2016 and compared to age-, sex-, and body mass index (BMI)-matched controls. Anthropometric parameters and medical history were collected. The serum levels of VD and IL-17 were determined by radioimmunoassay and enzyme-linked immunosorbent assay, respectively.

RESULTS

Ninety-two severe OSAHS patients and thirty controls were enrolled in the study. All OSAHS patients had VD deficiency. The mean level of VD was at 7.9 ng/ml among OSAHS group versus 16.8 ng/ml among control group. IL-17A levels were elevated (20.3 pg/ml) in OSAHS group compared to healthy group (10.05 pg/ml). VD levels were negatively correlated with nocturia severity (r = -0.26; P = 0.01) and positively correlated with mean O₂ saturation (r = 0.59; P = 0.02) and lowest O₂ saturation (r = 0.3; P = 0.03). IL-17 levels were positively correlated with nocturia severity (r = 0.24; P = 0.03) and negatively correlated with mean O₂ saturation (r = -0.42; P = 0.03). A significant negative association was observed between IL-7 and VD levels (r = -0.64, P = 0.2 10^-4). The magnitude of this correlation was higher for important nocturia, lower MSaO₂, or higher BMI.

CONCLUSIONS

VD deficiency in patients with severe OSAHS is common with a negative association between IL-17 and VD serum levels. Hypoxia could play an important role in this association. Further studies are needed to clarify this relationship.

Risk assessment of obstructive sleep apnea syndrome in pediatric patients with vitamin D deficiency: A questionnaire-based study

The aim of the following study is to evaluate the risk of obstructive sleep apnea syndrome (OSAS) in subjects with vitamin D deficiency.Prospective and comparative study.We enrolled 240 subjects into the study. The participants were divided into 2 groups based on 25-hydroxyvitamin D (25[OH]D) levels: low level of 25(OH)D (<20 ng/mL) group (n = 120) and control (>20 ng/mL) group (n = 120). Subjects were classified as being at a high or low risk of developing OSAS by using the Berlin Questionnaire. Risk of developing OSAS, gender, age, and body mass index (BMI) z-score were assessed by comparing the low level of 25(OH)D group and control group.No statistically significant difference was observed between the low level of 25(OH)D group and control group in terms of gender, age, and BMI z-score distributions; P = 0.323, P = 0.387, and P = 0.093, respectively. There were 24 subjects with high risk of developing OSAS in 2 groups (17 subjects in the low level of 25[OH]D group and 7 subjects in the control group). In the low level of 25(OH)D group, the risk of developing OSAS was found to be significantly higher than the control group (P = 0.030). BMI z-score was found significantly higher in high-risk groups than low-risk groups (P = 0.034 for low-level 25[OH]D group and P = 0.023 for control group).The findings revealed that low level of 25(OH)D increases the risk of developing OSAS.