Vitamin D-deficient Individuals Research Articles

A cohort study of serum 25-hydroxyvitamin D levels and the risk of hyperlipidaemia in adults

ObjectiveThis study aims to investigate the potential association between serum 25(OH)D levels and the risk of hyperlipidemia in adults through a prospective cohort study conducted in Zhejiang Province.MethodsBaseline surveys and follow-up studies were conducted to collect and analyze follow-up data over a three-year period. Vitamin D deficiency was defined as 25(OH)D < 20 ng/mL, insufficiency as 20–29 ng/mL, and sufficiency as 25(OH)D ≥ 30 ng/mL. Hyperlipidemia or dyslipidemia was defined as the presence of hypercholesterolemia, hypertriglyceridemia, or both. The relationship between demographic characteristics and the incidence of hyperlipidemia among the study participants was explored.ResultsA total of 1,210 participants were included in this study, with 43.80% being male. The mean age of the participants was 51.84 ± 14.37 years, and the average serum 25(OH)D level was 25.89 (21.50, 29.82) ng/mL. A significant difference in the proportion of vitamin D deficiency was observed between males and females (22.06% vs. 10.94%, p < 0.001). Vitamin D deficiency and insufficiency were prevalent among the middle-aged and elderly population (78.24%). Significant differences were found between the two groups in multiple sociodemographic variables, behavioral factors, and metabolic risk factors (p < 0.05). The incidence of hyperlipidemia among vitamin D-deficient individuals was 1.612 times higher than that among vitamin D-sufficient individuals (95% confidence interval [CI]: 1.228–2.116; p < 0.001). After fully adjusting for confounding factors, the multivariate-adjusted hazard ratio (HR) was 1.572 (95% CI: 1.187–2.08; p = 0.002), indicating a difference in the incidence of hyperlipidemia across different serum vitamin D levels.ConclusionThis cohort study reveals a significant association between serum 25(OH)D levels and the incidence of hyperlipidemia. Additionally, lifestyle factors associated with vitamin D deficiency are also correlated with the incidence of hyperlipidemia. These findings provide further evidence for improving blood lipid profiles through adjustments in vitamin D intake or related lifestyle modifications.

A review of vitamin D deficiency and vitamin D receptor polymorphisms in endocrine-related disorders.

The endocrine system is a complex network of glands that produce and release hormones that regulate various physiological processes. In the past few decades, the human skin has been identified as an important peripheral endocrine organ that is the main site for the synthesis of vitamin D through exposure to sunlight. Mutations in downstream vitamin D-related gene pathways are associated with disease development. The vitamin D receptor (VDR) gene, which regulates the pleiotropic effects of vitamin D, has been extensively studied in adult populations. Several studies have reported the prevalence of vitamin D deficiency in children and adolescents. With changes in socioeconomic status and lifestyle, vitamin D-deficient individuals are prone to developing the disease at a young age. However, geographical and racial differences affect the association between VDR gene polymorphisms and vitamin D endocrine disorders, explaining the nonconsensus effects of polymorphisms and their association with disease development across populations. In this review, we discuss the connection between the vitamin D endocrine system and polymorphisms in the gene encoding VDR in children and adolescents, focusing on its effects on growth, puberty, insulin resistance, and the immune system.

Vitamin D Deficiency Exacerbates Poor Sleep Outcomes with Endocrine-Disrupting Chemicals Exposure: A Large American Population Study.

Phthalates and bisphenol A are recognized as the predominant endocrine-disrupting substances (EDCs) in the environment, but their impact on sleep health remains unclear. Vitamin D has often been reported to play a role in sleep health and may be affected by endocrine-disrupting compounds. The study utilized data from 5476 individuals in the NHANES project to investigate the correlation between combined exposure to environmental EDCs and sleep duration through modeling various exposures. Furthermore, it emphasizes the importance of vitamin D in the present scenario. Preliminary analyses suggested that vitamin D-deficient individuals generally slept shorter than individuals with normal vitamin D (p < 0.05). Exposure to Mono-ethyl phthalate (MEP), triclosan (TRS), and Mono-benzyl phthalate (MZP), either alone or in combination, was associated with reduced sleep duration and a greater risk of vitamin D deficiency. Individuals with low vitamin D levels exposed to TRS experienced shorter sleep duration than those with normal vitamin D levels (p < 0.05). TRS and MZP were identified as crucial factors in patient outcomes when evaluating mixed exposures (p < 0.05). The results provide new data supporting a link between exposure to EDCs and insufficient sleep length. Additionally, they imply that a vitamin D shortage may worsen the sleep problems induced by EDCs.

Exploration of smart adherence-monitoring methods in vitamin D-deficient patients: A pilot feasibility clinical study.

Treatment adherence is an underestimated determinant of treatment success. Poor treatment adherence can also affect the efficacy of clinical trials. A combination of multiple adherence-monitoring methods is required to ensure robustness. We investigated whether multiple adherence-monitoring methods, including a novel smartwatch-based monitoring method, would yield reliable and concordant results. In this open, randomized, decentralized clinical trial, vitamin D-deficient individuals were randomized to an App - only group (an electronic medication diary) or an App + Watch group (i.e., App and smartwatch-based monitoring) groups after a week run-in period. The participants received vitamin D supplements (1000 IU) for 12 weeks (two consecutive periods of 6 weeks) with two pill counts (at the sixth week) and biweekly blood samplings for serum 25(OH) vitamin D concentration. Adherence was assessed and compared between the methods. Sixteen participants were enrolled, of which 13 completed the study. Serum 25(OH) vitamin D levels comparably increased in both groups until the first 7 weeks but trended higher in the App + Watch group in the second period. The number of doses recorded by the pill count and App did not differ significantly between the run-in and Period 1 (p = 0.5534) but became significantly discrepant in Period 2 (p = 0.0225). In contrast, the concordance for smartwatch-based monitoring was consistent in either period (p = 0.5898 and p = 0.5839, respectively). We explored multiple adherence-monitoring methods in this pilot feasibility clinical study. Smartwatch-based adherence monitoring may be an objective and sensitive method for measuring treatment adherence.

Association between vitamin D deficiency and vasovagal syncope: A systematic review and meta-analysis.

Vasovagal syncope (VVS) is the most prevalent type of syncope and its management includes pharmacologic and non-pharmacologic interventions. Recently, studies have investigated vitamin D levels in VVS patients. In this systematic review and meta-analysis, we aim to review these studies to find possible associations between vitamin D deficiency and vitamin D levels with VVS. International databases including Scopus, Web of Science, PubMed, and Embase were searched with keywords related to "vasovagal syncope" and "vitamin D." Studies were screened and the data were extracted from them. Random-effect meta-analysis was conducted to calculate the standardized mean difference (SMD) and 95% confidence interval (CI) for vitamin D levels in comparison to VVS patients and controls. Also, VVS occurrence was measured and the odds ratio (OR) and 95% CI were calculated for comparison of vitamin D deficient cases and nondeficient individuals. Six studies were included with 954 cases investigated. Meta-analysis showed that patients with VVS had significantly lower vitamin D serum levels in comparison to non-VVS cases (SMD -1.05, 95% CI -1.54 to -0.57, p-value < .01). Moreover, VVS occurrence was higher in vitaminD-deficient individuals (OR 5.43, 95% CI 2.40 to 12.27, p-value < .01). Our findings which show lower vitamin D levels in VVS patients can have clinical implications in order for clinicians to pay attention to this when approaching VVS. Further randomized controlled trials are certainly warranted to assess the role of vitamin D supplementation in individuals with VVS.

Determination of vitamin D3 conjugated metabolites: a complementary view on hydroxylated metabolites.

Experts typically define vitamin D deficiency levels by the determination of a circulating 25-hydroxyvitamin D3-calcifediol prohormone. A large part of the population is characterized by deficient vitamin D levels (calcifediol < 20 ng mL-1) despite individuals not being affected by any disorder. Cholecalciferol (vitamin D3) and/or calcifediol supplementation is a common practice for vitamin D-deficient individuals as recommended by international scientific societies and official agencies. In the last few years, several studies have reported the presence of conjugated vitamin D3 metabolites, mainly glucuronidation and sulfation derivatives, although simultaneous quantitative measurements involving phase I and II vitamin D metabolites have not been carried out. A quantitative method based on tandem mass spectrometry detection is proposed here for the combined determination of phase I and phase II vitamin D3 metabolites in human serum. As phase I and phase II metabolites are preferentially ionized in different modes, a switching polarity mode was adopted to determine both groups of compounds in serum at high sensitivity levels (pg mL-1). The validation of this proposal was successfully accomplished by following the Center for Drug Evaluation and Research (CDER) guidelines. Its applicability was tested in a cohort of volunteers with mostly deficient baseline levels. Considering the sulfated form of calcifediol, the sum of its concentrations showed sufficient baseline vitamin D levels in all individuals, suggesting that this could be a novel strategy for vitamin D deficiency definition. Therefore, phase II metabolites are proposed to be included when evaluating the vitamin D status since they provide more information about the overall status of the vitamin D endocrine system. Nevertheless, further studies are required to confirm the biological activity of these conjugated metabolites and the suitability of this strategy for the description of vitamin D deficiency.

Vitamin D deficit is associated with accelerated brain aging in the general population

Vitamin D deficiency has been associated with reduced neurocognitive functioning and the neurodegenerative processes. However, existing evidence on brain structural correlates of vitamin D deficiency is controversial. We sought to investigate associations of vitamin D levels with imaging patterns of brain aging. In addition, we investigated whether low vitamin D levels were associated with gray matter volumes, whole brain volumes and hippocampus volumes. Structural MRI data and vitamin D levels were obtained in 1,865 subjects from the general population. Linear regressions were applied to investigate the association of vitamin D levels and vitamin D deficiency with imaging derived brain age, total brain, gray matter and hippocampal volumes. Different sets of covariates were included. Vitamin D deficiency was significantly associated with increased brain age. Also, linear vitamin D levels were significantly associated with total brain and gray matter volumes, while no significant association with hippocampal volume was found. Further interaction analyses showed that this association was only significant for male subjects. Our results support previous findings suggesting that vitamin D-deficient individuals have an accelerated brain aging. In addition, associations between vitamin D levels and total brain/ gray matter volumes suggest neuroprotective effects of vitamin D on the brain.

The Efficacy of Vitamin D Supplementation in the Treatment of Fibromyalgia Syndrome and Chronic Musculoskeletal Pain.

Fibromyalgia syndrome (FMS) and chronic widespread musculoskeletal pain (CMP) are diffuse suffering syndromes that interfere with normal activities. Controversy exists over the role of vitamin D in the treatment of these diseases. We carried out a systematic literature review of randomized controlled trials (RCT) to establish whether vitamin D (25OHD) deficiency is more prevalent in CMP patients and to assess the effects of vitamin D supplementation in pain management in these individuals. We searched PubMed, Physiotherapy Evidence Database (PEDro), and the Cochrane Central Register of Controlled Trials (CENTRAL) for RCTs published in English from 1 January 1990 to 10 July 2022. A total of 434 studies were accessed, of which 14 satisfied the eligibility criteria. In our review three studies, of which two had the best-quality evidence, a correlation between diffuse muscle pain and 25OHD deficiency was confirmed. Six studies, of which four had the best-quality evidence, demonstrated that appropriate supplementation may have beneficial effects in patients with established blood 25OHD deficiency. Eight studies, of which six had the best-quality evidence, demonstrated that 25OHD supplementation results in pain reduction. Our results suggest a possible role of vitamin D supplementation in alleviating the pain associated with FMS and CMP, especially in vitamin D-deficient individuals.

Effects of Vitamin D Supplementation on 24-Hour Blood Pressure in Patients with Low 25-Hydroxyvitamin D Levels: A Randomized Controlled Trial.

Accumulating evidence suggests that potential cardiovascular benefits of vitamin D supplementation may be restricted to individuals with very low 25-hydroxyvitamin D (25(OH)D) concentrations; the effect of vitamin D on blood pressure (BP) remains unclear. We addressed this issue in a post hoc analysis of the double-blind, randomized, placebo-controlled Styrian Vitamin D Hypertension Trial (2011–2014) with 200 hypertensive patients with 25(OH)D levels <30 ng/mL. We evaluated whether 2800 IU of vitamin D3/day or placebo (1:1) for 8 weeks affects 24-hour systolic ambulatory BP in patients with 25(OH)D concentrations <20 ng/mL, <16 ng/mL, and <12 ng/mL and whether achieved 25(OH)D concentrations were associated with BP measures. Taking into account correction for multiple testing, p values < 0.0026 were considered significant. No significant treatment effects on 24-hour BP were observed when different baseline 25(OH)D thresholds were used (all p-values > 0.30). However, there was a marginally significant trend towards an inverse association between the achieved 25(OH)D level with 24-hour systolic BP (−0.196 per ng/mL 25(OH)D, 95% CI (−0.325 to −0.067); p = 0.003). In conclusion, we could not document the antihypertensive effects of vitamin D in vitamin D-deficient individuals, but the association between achieved 25(OH)D concentrations and BP warrants further investigations on cardiovascular benefits of vitamin D in severe vitamin D deficiency.

Beneficial Role of Vitamin D on Endothelial Progenitor Cells (EPCs) in Cardiovascular Diseases.

Cardiovascular diseases (CVDs) are the leading cause of death in the world. Endothelial progenitor cells (EPCs) are currently being explored in the context of CVD risk. EPCs are bone marrow derived progenitor cells involved in postnatal endothelial repair and neovascularization. A large body of evidence from clinical, animal, and in vitro studies have shown that EPC numbers in circulation and their functionality reflect endogenous vascular regenerative capacity. Traditionally vitamin D is known to be beneficial for bone health and calcium metabolism and in the last two decades, its role in influencing CVD and cancer risk has generated significant interest. Observational studies have shown that low vitamin D levels are associated with an adverse cardiovascular risk profile. Still, Mendelian randomization studies and randomized control trials (RCTs) have not shown significant effects of vitamin D on cardiovascular events. The criticism regarding the RCTs on vitamin D and CVD is that they were not designed to investigate cardiovascular outcomes in vitamin D-deficient individuals. Overall, the association between vitamin D and CVD remains inconclusive. Recent clinical and experimental studies have demonstrated the beneficial role of vitamin D in increasing the circulatory level of EPC as well as their functionality. In this review we present evidence supporting the beneficial role of vitamin D in CVD through its modulation of EPC homeostasis.

Determination of serum 25-hydroxyvitamin D levels in patients with alopecia areata and their comparison with levels in healthy controls: A cross-sectional study

BackgroundAlopecia areata (AA) has been postulated to be an autoimmune disease affecting the hair follicles. Because vitamin D receptors are present in the immune system and hair follicles, vitamin D has been hypothesized to affect the disease.ObjectiveThe aim of this study was to determine serum 25-hydroxyvitamin D levels and the percentage of vitamin D deficiency in AA patients and compare them with those in healthy controls in a Philippine tertiary hospital.MethodsThis cross-sectional study included 29 AA patients and 29 healthy controls. The serum 25-hydroxyvitamin D levels were determined using the chemiluminescent immunoassay method.ResultsThere was no significant difference in the mean vitamin D levels between AA patients (24.41 ± 6.87 ng/mL) and healthy controls (24.68 ± 6.68 ng/mL) (P = .88). The percentage of patients with vitamin D deficiency, defined as <20 ng/mL, trended to higher among AA patients (34.4%) than among healthy controls (17.2%), with an odds ratio of 2.53 (95% CI 0.73-8.65), though this was not statsitically significant.LimitationsThis study involved a limited number of patients in an urbanized area in the Philippines, and majority of the AA cases seen had mild AA.ConclusionThe trend toward the increased percentage of vitamin D-deficient individuals among AA patients seen in this study may provide insight into the association of vitamin D with AA.

Влияние обеспечения витамином D на аутоиммунное состояние щитовидной железы

Актуальность. Несмотря на большой объем данных, связывающих витамин D с сердечно-сосудистой заболеваемостью, аутоиммунитетом, раком и практически каждой системой органов, взаимосвязь между витамином D и щитовидной железой остается менее известным аспектом в клинической практике. Причиной активного влияния витамина D является тот факт, что рецепторы витамина D (VDR) размещены практически в каждой ткани и системе органов организма. Цель: осветить данные современной литературы о влиянии витамина D и его обеспечения на аутоиммунитет щитовидной железы. Материалы и методы. Источники этого обзора были определены с помощью поиска в PubMed по статьям, опубликованным с 2015 года по сентябрь 2020 года, с использованием терминов «щитовидная железа» и «витамин D». Результаты. Зарегистрирована достоверная обратная корреляция между антителами к тиреоидной пероксидазе (АТ-ТПО) и содержанием 25-гидроксивитамина D (25(OH)D) в сыворотке крови. Наличие положительных титров АТ-ТПО более распространено у лиц с дефицитом витамина D. В большом объеме медицинской литературы приводятся результаты наблюдательных исследований, связывающих витамин D с аутоиммунитетом щитовидной железы. Также приводятся данные интервенционных исследований, подтверждающих положительное влияние витамина D на аутоиммунитет щитовидной железы. Краткосрочный прием высоких доз пероральных добавок витамина D содействует уменьшению титров АТ-ТПО. Некоторые полиморфизмы гена VDR связаны с увеличением случаев аутоиммунных расстройств щитовидной железы. Данные о том, приводит ли коррекция дефицита витамина D при аутоиммунных расстройствах щитовидной железы к снижению потребности в левотироксине или карбимазоле соответственно при гипотиреозе или болезни Грейвса, отсутствуют. Выводы. Несмотря на большой объем медицинской литературы по обсервационным исследованиям, в которых связывают витамин D с аутоиммунитетом щитовидной железы, отсутствуют важные конкретные клинические данные о влиянии дополнительного назначения витамина D на основные клинические конечные точки при этих расстройствах. Это должно быть основной сферой исследований в следующем десятилетии.

COVID-19: possible role of vitamin D supplementation in preventing infection and reducing symptom severity

The COVID-19 pandemic and its consequences have demonstrated that viral infections still pose great challenge to health systems worldwide. The immune system plays a primary role in fighting infections, and non-specific innate immunity, in particular, is a key defense mechanism engaged during the first phases of an infection. The subsequent triggered immune response, characterized by specific cytokine patterns, can be exaggerated and lead to a cytokine storm, causing multiorgan damage and intravascular disseminated coagulation. Calcitriol, the active form of vitamin D, a key player in mineral homeostasis, is able to control the immune response by favoring the production of antimicrobial peptides (e.g., cathelicidin), decreasing viral shedding, and modulating the inflammatory process. A poor vitamin D status has been demonstrated to be associated with increased risk of infections, especially in fragile subjects, as also recently shown in COVID-19 disease. Unfortunately, this does not demonstrate that supplementation with vitamin D is significantly linked to prevention or modulation of the course of viral infections. Large intervention trials are necessary to produce evidence that vitamin D supplementation is linked to decreased rates of infections and related complications. At present, cholecalciferol and calcidiol regimens commonly employed in clinical practice to prevent and correct musculoskeletal abnormalities are advisable, at least in fragile, vitamin D-deficient individuals, in order to reach a target of serum 25(OH)D of 30–50 ng/ml, avoiding large doses, which can be responsible for hypercalciuria-hypercalcemia or increased falls.

Vitamin D deficiency and lung function decline in healthy individuals: A large longitudinal observation study

AimA reliable evidence from a comprehensive large-scale study supporting associations between serum vitamin D (25-hydroxyvitamin D) level (SVDL) and lung function decline (LFD) in healthy individuals has been unavailable. Using a well-established health screening database, we assessed the associations between SVDL and LFDs, measured as the forced vital capacity (FVC), forced expiratory volume in 1 s (FEV1) and FEV1/FVC ratio. MethodsSerial SVDL and lung function data were analyzed using linear mixed models, which were performed in smokers and non-smokers, separately. Vitamin D-deficient individuals (VDDs) were defined when their SVDLs were consistently lower than 20 ng/mL at all measurements. ResultsA total of 1371 individuals were analyzed. The mean FEV1 decline rates of VDDs and vitamin D-normal individuals (VDNs) in smokers were −33.35 mL/year (95% CI: 39.44 to −27.26 mL/year) and −15.61 mL/year (95% CI: 27.29 to −4.21 mL/year) respectively, over a mean of 6.29 years of observation with statistical significance (P < 0.001). However, there was no significant differences observed between decline rates of FEV1 in non-smokers. Similarly, FVC decline rates of VDDs were significantly greater than those of VDNs only in smokers (P < 0.001). However, FEV1/FVC ratio decline rates showed no significant difference between VDDs and VDNs regardless of their smoking status. ConclusionsConsistently low SVDLs predicted more rapid FEV1 and FVC declines in smokers. However, FEV1/FVC decline rate was not associated with SVDL. SVDL may be used to identify healthy smoking individuals at high risk for accelerated LFD.

Short term, high-dose vitamin D supplementation for COVID-19 disease: a randomised, placebo-controlled, study (SHADE study)

BackgroundVitamin D has an immunomodulatory role but the effect of therapeutic vitamin D supplementation in SARS-CoV-2 infection is not known.AimEffect of high dose, oral cholecalciferol supplementation on SARS-CoV-2 viral clearance.DesignRandomised,...

Immune Modulatory Effects of Vitamin D on Viral Infections.

Viral infections have been a cause of mortality for several centuries and continue to endanger the lives of many, specifically of the younger population. Vitamin D has long been recognized as a crucial element to the skeletal system in the human body. Recent evidence has indicated that vitamin D also plays an essential role in the immune response against viral infections and suggested that vitamin D deficiency increases susceptibility to viral infections as well as the risk of recurrent infections. For instance, low serum vitamin D levels were linked to increased occurrence of high burdens viral diseases such as hepatitis, influenza, Covid-19, and AIDS. As immune cells in infected patients are responsive to the ameliorative effects of vitamin D, the beneficial effects of supplementing vitamin D-deficient individuals with an infectious disease may extend beyond the impact on bone and calcium homeostasis. Even though numerous studies have highlighted the effect of vitamin D on the immune cells, vitamin D’s antiviral mechanism has not been fully established. This paper reviews the recent mechanisms by which vitamin D regulates the immune system, both innate and adaptive systems, and reflects on the link between serum vitamin D levels and viral infections.

Effects of Vitamin D on Depression, Cognitive Function, and Physical Function in Elderly Individuals Living Alone

Background: We examined the effects of vitamin D on depression, cognitive function, and physical function in elderly, community-dwelling individuals living alone. Methods: In this non-equivalent, control-group experimental study, participants with serum vitamin D levels ＜ 20 ng/mL and who lived alone were enrolled from eight senior centers in S city, Gyeonggi-do. Forty-six individuals were assigned to the experimental group and forty-eight to the control group. Vitamin D supplements and exercise programs were prescribed to the experimental group; the control group was prescribed only exercise programs. Treatment duration was 12 weeks. Depression, cognitive function, physical function (muscle mass, grip strength, static balance, time to walk a standard course, and arm flexibility), vitamin D and calcium levels were measured before and after treatment. Collected data were analyzed using chi-squared test, Fisher's exact test, t-test and multivariate logistic regression analysis. Results: Depression levels and cognitive function improved in both groups, the difference was not significant. Vitamin D levels (p ＜ 0.001), muscle mass (p = 0.014), and time to walk a standard course (p = 0.012) improved in the experimental group. Conclusion: Vitamin D supplementation for 12 weeks in vitamin-D deficient elderly individuals living alone was associated with improved vitamin D levels, muscle mass, and time to walk a standard course.

Biochemical spectrum of parathyroid disorders diagnosed at a tertiary care setting.

To determine the clinical and biochemical pattern of parathyroid disorders in a tertiary care setting.. The cross-sectional study was conducted at the Armed Forces Institute of Pathology, Rawalpindi, Pakistan, from September 2017 to February 2018, and comprised patients with suspected parathyroid disorders. A panel of biochemical tests were used for diagnosis of parathyroid disorders, which included parathyroid hormone levels, total calcium, ionized calcium, inorganic phosphorus, alkaline phosphatase, magnesium, total vitamin D and urinary calcium-to-creatinine ratio. SPSS 24 was used for data analysis. Of the 384 subjects, 248(65%) were male and 136(35%) were female. Overall mean age was 48±19years. Of the total, 302(786%) had parathyroid issues, with 244(81%) having secondary hyperparathyroidism. Mean serum total calcium, phosphorus, ionized calcium, magnesium and total vitamin D were 8.98±1.52 mg/dl, 4.0±1.30 mg/dl, 4.65±0.52 mg/dl, 2.11±0.27 mg/dl and 20.5±8.52 ngml respectively. Of the patients diagnosed with secondary hyperparathyroidism, 72.2% patients had chronic kidney disease and 20.2% had isolated vitamin D deficiency. Parathyroid disorders had significant impact on bone health. Moreover, secondary hyperparathyroidism was seen to be emerging as a major endocrine problem, especially in chronic kidney disease patients and vitamin D-deficient individuals.

Vitamin D attenuates rhinovirus-induced expression of intercellular adhesion molecule-1 (ICAM-1) and platelet-activating factor receptor (PAFR) in respiratory epithelial cells

Human rhinoviruses commonly cause upper respiratory infections, which may be complicated by secondary bacterial infection. Vitamin D replacement reduces risk of acute respiratory infections in vitamin D-deficient individuals, but the mechanisms by which such protection is mediated are incompletely understood. We therefore conducted experiments to characterise the influence of the major circulating metabolite 25-hydroxyvitamin D (25[OH]D) and the active metabolite 1,25-dihydroxyvitamin D (1,25[OH]2D) on responses of a respiratory epithelial cell line (A549 cells) to infection with a major group human rhinovirus (RV-16). Pre-treatment of A549 respiratory epithelial cells with a physiological concentration (10−7M) of 25(OH)D induced transient resistance to infection with RV-16 and attenuated RV-16-induced expression of the genes encoding intercellular adhesion molecule 1 (ICAM-1, a cell surface glycoprotein that acts as the cellular receptor for major group rhinoviruses) and platelet-activating factor receptor (PAFR, a G-protein coupled receptor implicated in adhesion of Streptococcus pneumoniae to respiratory epithelial cells). These effects were associated with enhanced expression of the genes encoding the NF-κB inhibitor IκBα and the antimicrobial peptide cathelicidin LL-37. Our findings suggest possible mechanisms by which vitamin D may enhance resistance to rhinovirus infection and reduce risk of secondary bacterial infection in vitamin D-deficient individuals.

The Effect of Abnormal Vitamin D Levels in Athletes.

Vitamin D is a lipophilic prohormone integral to musculoskeletal, autoimmune, oncologic, cardiovascular, and mental health. Of particular importance to the orthopedic surgeon is the role of vitamin D in the regulation of bone mass, muscle strength, and physical performance. Although vitamin D-related skeletal pathologies are rare in industrialized nations, emerging research in the field has shown that most American adults have inadequate levels of vitamin D. Even among athletes, there is a high prevalence of vitamin D deficiency, which may place competitors at risk of stress fractures, illness, and delayed muscle recovery. Adequately identifying vitamin D-deficient individuals in need of supplementation is important to help optimize performance and prevent future injury. The goal of this review is to describe the epidemiology of vitamin D deficiency and its effects on athletic performance and musculoskeletal health. Future double-blinded studies of vitamin D supplementation in athletes are needed. We recommend treating athletes who have insufficient or deficient vitamin D levels.