The noncalciotropic actions of vitamin D: recent clinical developments

Optimal serum 25-hydroxyvitamin D level to prevent sarcopenia in patients with heart failure: Insights from a dose-response relationship

BACKGROUND AND AIMS

Low serum 25-hydroxyvitamin D (25 [OH]D) levels have been associated with sarcopenia, frailty, and risk of cardiovascular disease, whereas high levels negatively impact clinical outcomes. We determined optimal serum 25(OH)D concentrations to minimise the probability of sarcopenia in patients with heart failure (HF) by examining the dose-dependent relationship between serum 25(OH)D levels and sarcopenia.

METHODS AND RESULTS

We enrolled 461 consecutive patients with HF (mean age, 72 ± 15 years; 39% female) who underwent dual-energy X-ray absorptiometry. Serum 25(OH)D levels were measured using a chemiluminescence immunoassay. Sarcopenia was diagnosed according to the 2019 Asian Working Group for Sarcopenia criteria. Overall, 49% of enrolled patients were diagnosed with sarcopenia. Adjusted logistic regression with restricted cubic spline function revealed that the odds ratio (OR) of sarcopenia increased in patients with HF presenting serum 25(OH)D levels <14.6 ng/ml or > 31.4 ng/ml, reaching the lowest OR at ∼20 ng/ml. Multivariate logistic regression revealed that a serum 25(OH)D level below 14.6 ng/mL was independently associated with the presence of sarcopenia (adjusted OR: 2.16, 95% confidence interval [CI]: 1.24-3.78). Incorporating serum 25(OH)D levels <14.6 ng/ml, but not <20.0 ng/ml, in the baseline model improved continuous net reclassification (0.334, 95% CI: 0.122-0.546) in patients with HF.

CONCLUSION

A U-shaped relationship exists between serum 25(OH)D levels and sarcopenia probability in patients with HF. Maintaining serum 25(OH)D levels between 14.6 and 31.4 ng/ml may help prevent sarcopenia in patients with HF.

Left and right ventricular function by echocardiography, tissue doppler imaging, carotid intima media thickness, and asymmetric dimethylarginine levels in female adolescents with vitamin D deficiency

BACKGROUND

The aim of our study was to assess left and right ventricle systolic and diastolic functions in female adolescents with vitamin D deficiency using conventional echocardiography and pulsed-wave tissue Doppler imaging and to investigate carotid intima media thickness and asymmetric dimethylarginine levels.

METHODS

Sixty-six female adolescents were enrolled in this study. The female adolescents were divided into a vitamin D deficiency group (n: 34) and a control group (n: 32). All subjects underwent laboratory blood tests, including asymmetric dimethyl arginine, complete two-dimensional, pulse, and tissue Doppler echocardiography, and measurement of the carotid intima-media thickness.

RESULTS

The vitamin D-deficient female adolescent group had normal left and right ventricle systolic and diastolic functions and normal global systolic and diastolic myocardial performance. In the patients with vitamin D deficiency, the carotid intima-media thickness was higher than that in the controls. In the patients within the vitamin D deficiency group, vitamin D was found to be positively correlated with magnesium and negatively correlated with phosphorus and left atrial dimension.

CONCLUSIONS

The results of this study demonstrate that vitamin D deficiency in female adolescence is associated with normal myocardial geometry and function. Although it has been associated with normal levels of asymmetric dimethyl arginine concentration, high measured carotid intima-media thickness may reflect endothelial dysfunction.

Vitamin D Status and Health Outcomes in School Children in Northern Ireland: Year One Results from the D-VinCHI Study

(1) Background: Vitamin D status has never been investigated in children in Northern Ireland (UK). (2) Methods: Children (4-11 years) (n = 47) were recruited from November 2019 to March 2020 onto the cross-sectional study. Anthropometry was assessed. Plasma 25-hydroxyvitamin D (25(OH)D) was analysed. Vitamin D intake, parental knowledge and perceptions, participant habits, physical activity and sedentary behaviour were established via questionnaire. Muscle strength was assessed via isometric grip strength dynamometry and balance via dominant single-leg and tandem stance. Parathyroid hormone, bone turnover markers (OC, CTX and P1NP), glycated haemoglobin and inflammatory markers (CRP, IFN-γ, IL-10, IL-12p70, IL-13, IL-1β, IL-2, IL-4, IL-6, IL-8 and TNF-α) were analysed. (3) Results: Mean (SD) 25(OH)D was 49.17 (17.04) nmol/L (n = 47); 44.7% of the children were vitamin D sufficient (25(OH)D >50 nmol/L), 48.9% were insufficient (25-50 nmol/L) and 6.4% were deficient (<25 nmol/L). 25(OH)D was positively correlated with vitamin D intake (µg/day) (p = 0.012, r = 0.374), spring/summer outdoor hours (p = 0.006, r = 0.402) and dominant grip strength (kg) (p = 0.044, r = 0.317). Vitamin D sufficient participants had higher dietary vitamin D intake (µg/day) (p = 0.021), supplement intake (µg/day) (p = 0.028) and spring/summer outdoor hours (p = 0.015). (4) Conclusion: Over half of the children were vitamin D deficient or insufficient. Wintertime supplementation, the consumption of vitamin D rich foods and spring/summer outdoor activities should be encouraged to minimise the risk of vitamin D inadequacy.

Influences of dietary vitamin D3 on growth, antioxidant capacity, immunity and molting of Chinese mitten crab (Eriocheir sinensis) larvae

This study investigates the effects of vitamin D₃ (VD₃) on growth performance, antioxidant capacity, immunity and molting of larval Chinese mitten crab Eriocheir sinensis. A total of 6,000 larvae (7.52 ± 0.10 mg) were fed with six isonitrogenous and isolipidic experimental diets with different levels of dietary VD₃ (0, 3000, 6000, 9000, 12000 and 36000 IU/kg) respectively for 23 days. The highest survival and molting frequency were found in crabs fed 6000 IU/kg VD₃. Weight gain, specific growth rate, and carapace growth significantly increased in crabs fed 3000 and 6000 IU/kg VD₃ compared to the control. Broken-line analysis of molting frequency, weight gain and specific growth rate against dietary VD₃ levels indicates that the optimal VD₃ requirement for larval crabs is 4825-5918 IU/kg. The highest whole-body VD₃ content occurred in the 12000 IU/kg VD₃ group, and the 25-dihydroxy VD₃ content decreased with the increase of dietary VD₃. The malonaldehyde content was lower than the control. Moreover, the superoxide dismutase activity, glutathione peroxidase and total antioxidant capacity of crab fed 6000 IU/kg VD₃ were significantly higher than in control. Crabs fed 9000 IU/kg showed the highest survival after 120 h of salinity stress, and the relative mRNA expressions indicate vitamin D receptor (VDR) is the important regulatory element in molting and innate immunity. The molting-related gene expressions showed that the response of crab to salinity was self-protective. This study would contribute to a new understanding of the molecular basis underlying molting and innate immunity regulation by vitamin D₃ in E. sinensis.

Lymphocyte and monocyte vitamin D receptor expression during paricalcitol or calcitriol treatments in patients with stage 5 chronic kidney disease

PURPOSE

In this study, we aimed to investigate the effect of paricalcitol and calcitriol usage on vitamin D receptor (VDR) contents of CD8+ , CD4+ lymphocytes and monocytes in stage 5d chronic kidney disease (CKD) patients.

METHODS

Thirty-six hemodialysis patients older than 18 years of age and 19 healthy controls (group HC) without any known acute or chronic diseases were included in the study. The group of patients undergoing scheduled hemodialysis comprised three subgroups: group CL: patients on calcitriol (n: 10), group PC: patients on paricalcitol (n: 13), and group NT: patients not taking any vitamin D or VDR activating medications (n: 13). CD8+/VDR, CD4+/VDR and MONO/VDR values were representing the ratio of VDR representing cells among related cell group. On the other hand, values of CD8+/MFI, CD4+/MFI and MONO/MFI have shown the total amount of cellular VDR content per cell which has been given as of mean fluorescence intensity in the flow cytometric process. Main CKD mineral bone disorder parameters such as a hemogram, serum BUN, creatinine, albumin, Ca, iP, iPTH, 25(OH)D₃ levels were also measured.

RESULTS

Average VDR contents in CD8+, CD4+ and monocytes were not different among three patient groups on hemodialysis. But in all hemodialysis subgroups, CD8+/VDR, CD4+/VDR, MONO/VDR, CD8+/MFI, CD4+/MFI and MONO/MFI levels were found to be higher compared with the healthy control subjects (p < 0.001). Among hemodialysis groups, no significant CD8+/VDR, CD4+/VDR, and MONO/VDR content differences were found with regard to the type of VDR activator agent used. There was no difference in serum levels of 25(OH)D₃ and CRP among groups participating in the study.

CONCLUSION

There was no difference between CD8+/VDR, CD4+/VDR, and MONO/VDR levels in hemodialysis patients using calcitriol or paricalcitol, suggesting that both treatment agents may have a similar effect on VDR contents in lymphocytes and monocytes in that patient population. But in all hemodialysis subgroups, CD8+/VDR, CD4+/VDR, and MONO/VDR levels were found to be higher compared with the healthy control subjects, suggesting an overexpression of VDR through a non CRP and/or 25(OH)D₃ dependent mechanism.

Vitamin D and Rehabilitation after Stroke: Status of Art

Stroke is the first cause of disability in the population and post-stroke patients admitted to rehabilitation units often present a malnutrition status which can influence nutritional indices and then vitamin levels. Vitamin D deficiency seems implicated beyond stroke severity and stroke risk, and also affects post-stroke recovery. Some studies on vitamin D levels and outcome in stroke patients are available but very few data on vitamin D levels and outcome after rehabilitation treatment are reported. This literature review shows the possible relationship between vitamin D deficiency and recovery in post-stroke patients undergoing rehabilitation treatment. Moreover, because several studies have reported that single nucleotide polymorphisms and promoter methylation in genes are involved in vitamin D metabolism and might affect circulating vitamin D levels, these aspects are evaluated in the current paper. From the studies evaluated in this review, it emerges that vitamin D deficiency could not only have an important role in the recovery of patients undergoing rehabilitation after a stroke, but that genetic and epigenetic factors related to vitamin D levels could have a crucial role on the rehabilitation outcome of patients after stroke. Therefore, further studies are necessary on stroke patients undergoing rehabilitation treatment, including: (a) the measurement of the 25(OH) vitamin D serum concentrations at admission and post rehabilitation treatment; (b) the identification of the presence/absence of CYP2R1, CYP27B1, CYP24A1 and VDR polymorphisms, and (c) analysis of the methylation levels of these genes pre- and post-rehabilitation treatment.

Risk Factors for Peritoneal Dialysis–Associated Peritonitis: The Role of Oral Active Vitamin D

Background

Peritonitis is a major complication of peritoneal dialysis (PD), being associated with hospitalization, catheter loss, technique failure, and increased mortality. Data on various risk factors for peritonitis are inconsistent, and no association with concomitant therapy has been shown.

Methods

We performed a retrospective analysis of all incident and prevalent PD patients ( n = 55) treated in Innsbruck, Austria, between 2000 and 2007. Data consisted of 1291 patient–months and 55 episodes of peritonitis. Patient demographic data, comorbidities, concomitant medication, laboratory parameters, and microbiology results were obtained from the medical records and from the hospital's electronic database.

Results

The mean peritonitis incidence rate was 0.51 episodes/patient–year (range: 0.24 – 0.73 episodes/patient–year) or 1 episode every 23.5 months (range: 16 – 50 months). In a primary analysis including demographic characteristics, comorbidities, laboratory parameters, and concomitant medication, only treatment with oral active vitamin D was associated with a significantly lower risk of peritonitis. Adjusted for time on PD and baseline serum albumin, oral active vitamin D therapy was associated with an 80% reduced relative risk of peritonitis [hazard ratio (HR): 0.20; 95% confidence interval (CI): 0.06 to 0.64; p = 0.007)]. The risk reduction was comparable in patients who received 0.25 μg or more of vitamin D daily (HR: 0.18; 95% CI: 0.05 to 0.65; p = 0.008) and in those who received less than 0.25 μg vitamin D daily (HR: 0.21; 95% CI: 0.06 to 0.77; p = 0.018).

Conclusions

Treatment with oral active vitamin D might be associated with a lower risk of peritonitis in PD patients.

Adequate 25-hydroxyvitamin D levels are inversely associated with various cardiometabolic risk factors in Chinese children, especially obese children

OBJECTIVE

Vitamin D deficiency has recently evolved as a major public health issue worldwide. But the relationship between vitamin D and cardiovascular health in children remains unclear. Accordingly, we aimed to examine the associations between 25-hydroxyvitamin D (25(OH)D) concentrations and cardiometabolic risk factors, and to assess the possible effect modification of obesity on the associations in a Chinese pediatric population.

RESEARCH DESIGN AND METHODS

A cross-sectional sample of 6091 children aged 6-18 years was obtained using a cluster sampling method. The 25(OH)D concentrations, and metabolic risk factors, including waist to height ratio, blood pressure, blood lipids, fasting blood glucose (FBG), and insulin were measured. Adjusted ORs and multiplicative or additive interaction were calculated to assess the associations and effect modification, respectively.

RESULTS

Triglycerides, FBG, insulin, and homeostasis model assessment of insulin resistance were inversely associated with 25(OH)D concentrations (p<0.05) in both sexes. The OR of hyperglycemia among individuals with insufficient vitamin D was higher than those with adequate vitamin D after adjusting for covariates (OR: 1.47; 95% CI 1.26 to 1.70). Moreover, girls with insufficient vitamin D had significantly higher odds for hypertension and high total cholesterol than those with adequate vitamin D, which was not observed in boys. Thirty-two percent (95% CI 14% to 51%) of the increased odds of hyperglycemia can be explained by the interaction between insufficient vitamin D and obesity.

CONCLUSIONS

Vitamin D insufficiency is associated with increased odds of various cardiometabolic risk factors in Chinese children and has a synergistic effect on hyperglycemia with obesity.

Evaluation of Serum Vitamin D Levels in Diabetic Foot Infections: A Cross-Sectional Study in a Tertiary Care Center in South India

Background

The impact of diabetic foot infections is enormous in India. Studies on vitamin D levels in diabetes mellitus foot infections are scarce. The primary objective of the present study was to compare the serum vitamin D level between diabetics with foot infections and those without foot infections and the secondary objective was to assess the association between the vitamin D level and the severity of foot infections and outcomes.

Methods

The study included 176 type 2 diabetics who attended Jawaharlal Institute of Postgraduate Medical Education and Research, Pondicherry, India, between September 2012 and June 2014. The serum vitamin D level was measured for 88 diabetics with foot infections (Group 1) and 88 without foot infections (Group 2) using the ELISA 25OH vitamin D DIAsource kit (DIAsource ImmunoAssays S.A., Belgium) and compared. Both groups were followed up for 6 months for outcomes. The qualitative variables were analyzed using the χ2 test and the quantitative variables using the Student t test. The statistical analyses were performed using SPSS, version 17.0. A P value of less than 0.05 was considered significant.

Results

The mean serum vitamin D level was not significantly different between the two groups (P=0.306). Among the patients in Group 1 who either required amputations or died, 97.44% had subnormal vitamin D levels in contrast to 59.18% in those who were grafted or achieved wound healing (P=0.001). Among those who achieved wound healing within 6 months, 78.9% had normal vitamin D levels (P=0.0006).

Conclusion

The study found no significant difference in the serum level of vitamin D between diabetics with and without foot infections. However, vitamin D deficiency was associated with a poor outcome in diabetics with foot infections.

The (Sun)Light and Dark of 25-Hydroxyvitamin D Testing

Background

Vitamin D is obtained by the body via sunlight on the skin, from the diet, or from supplementation. The primary function of vitamin D is to maintain calcium homeostasis and bone health, but in the past decade, numerous other health benefits have been proposed.

Content

With the increased awareness of the potential benefits of maintaining sufficient concentrations of 25-hydroxyvitamin D, clinicians began ordering this test for their patients much more frequently. The number of available methods increased, but with that came a larger focus on the challenges of measuring 25-hydroxyvitamin D accurately due to binding to vitamin D-binding protein and the presence of other vitamin D metabolites. Further, standardization of these assays became a focus for several organizations so that clinical guidelines can be applicable to every patient regardless of what methodology is used in 25-hydroxyvitamin D measurement.

Summary

Improvements are being made in the specificity, accuracy, and standardization of the measurement of 25-hydroxyvitamin D, and the future of this testing is looking brighter.

Vitamin D levels reverberate in monocytes modulation in hemodialysis patients

BACKGROUND

Patients with chronic kidney disease (CKD) have a severe vitamin D deficiency and increasing epidemiological data suggesting that this deficiency may play a role in overall morbidity and mortality associated with CKD. It is known that vitamin D regulates the immune system, however, in dialysis patients this deficiency and the modulation of proinflammatory cells is unclear. Among these, monocytes arouse interest considering they constitutively express vitamin D receptors.

AIM

This study aimed the evaluation of monocytic profile in CKD patients according to vitamin D levels.

METHODS

Patients in hemodialysis (HD) were divided into two groups, regarding vitamin D levels: Group 1, vitamin D <26 ng/ml (n = 15) and Group 2, vitamin D ≥26 ng/ml (n = 18). Whole blood was collected aiming evaluation of (a) monocytic populations through CD14 and CD16 expression, (b) reactive oxygen species (ROS) generation, and (c) apoptosis.

RESULTS

We observed that in Group 1, when compared to Group 2, there was a significant increase in intermediate monocytes (CD14⁺⁺ CD16 ⁺ ; 34.7 ± 31.6 vs. 12.1 ± 6.3; p = 0.006, respectively) and decrease in classical ones (CD14 ⁺⁺ CD16 ^- ; 45.3 ± 31.8 vs. 70.4 ± 25.1; p = 0.017, respectively). There was no difference between groups regarding nonclassical monocytes (CD14 ⁺ CD16 ⁺⁺ ), as well as to apoptosis and to ROS generation.

CONCLUSION

This study suggests that HD patients with lower vitamin D levels might have an intensified inflammatory outline as intermediate monocytes with an inflammatory pattern are increased in this population, when compared with patients with higher levels of vitamin D.

Association between vitamin D deficiency and lipid and non-lipid markers of cardiovascular diseases in the middle east region

BACKGROUND

Previous studies have associated vitamin D deficiency with cardiovascular disease (CVD) markers. The underlying mechanism remains elusive. Lipid and non-lipid markers of CVD and their relationship to vitamin D deficiency have not been assessed simultaneously.

OBJECTIVE

To measure the association between vitamin D deficiency and non-lipid markers of CVD after adjustment of lipid markers.

METHODS

This cross-sectional study used the following biological data, which was routinely collected in a general hospital laboratory database between 2011 and 2016: 25OH vitamin D [25(OH)D], creatinine, CKD-EPI eGFR (eGFR), fasting blood glucose (FPG), glycated hemoglobin (HbA1c), uric acid, γ-glutamyl transferase (γGT), C-reactive protein (CRP), total cholesterol, LDL cholesterol, HDL cholesterol, triglycerides, and a surrogate for CVD. Crude odds ratios (ORs) and ORs adjusted for lipid profile, gender and age using separate logistic regression models were derived.

RESULTS

A total of 8658 subjects were included. Half had 25(OH)D < 20 ng/mL. 25(OH)D was associated with increased odds of CRP, eGFR, increased uric acid, γGT, FPG, HbA1c, male gender, CV status, and abnormal lipid markers. After adjustment for lipid markers, age, and gender, vitamin D deficiency was associated with increased odds of CRP, eGFR, γGT, FPG, HbA1c, and the surrogate for CVD.

CONCLUSIONS

In this exploratory analysis, the first of its kind in the MENA region, vitamin D deficiency was associated with abnormal lipid markers, non-lipid markers of CVD, male gender, lower eGFR, and a surrogate variable for CVD. The association between vitamin D deficiency and non-lipid markers of CVD persisted after adjustment for lipid markers, age, and gender.

Lactase persistence may explain the paradoxical findings of high vitamin D concentrations in Europeans living in areas of low UV-B irradiation

BACKGROUND/OBJECTIVES

Vitamin D has a critical role in skeletal health and maintaining serum calcium levels. Calcium is needed for a variety of cellular and metabolic processes in the body. Large amounts of vitamin D can be produced in the skin when exposed to UV-B radiation. It is therefore a paradox that in Europe, Caucasians living in higher latitude countries, such as Scandinavia and Iceland, have higher serum vitamin D compared with those living in lower latitude. In a recent study of adult-type lactase persistence (LP), it was shown that Caucasian of European descent, who carried the C-13910T LP allele, had higher levels of total serum 25-hydroxyvitamin D compared with those who were lactase non-persistent. This was attributed to higher consumption of dairy. We postulated that the distribution of the LP C-13910T allele in Caucasian populations may explain the vitamin D concentration pattern seen in Europe.

SUBJECTS/METHODS

Baseline mean total serum 25 hydroxyvitamin D concentration from a clinical trial of post-menopausal women with osteoporosis was correlated to published LP frequencies in European populations.

RESULTS

In multiple regression analysis, mean total serum 25 hydroxyvitamin D concentrations in both winter and summer were in turn correlated to LP phenotype frequency (winter: r² = 0.51, p < 0.05; summer: r² = 0.4, p < 0.05).

CONCLUSIONS

High frequency of LP in northern Europe may explain high mean total serum 25 hydroxyvitamin D concentrations despite low UV-B radiation exposure.

Role of Vitamin D in Maintaining Renal Epithelial Barrier Function in Uremic Conditions

As current kidney replacement therapies are not efficient enough for end-stage renal disease (ESRD) treatment, a bioartificial kidney (BAK) device, based on conditionally immortalized human proximal tubule epithelial cells (ciPTEC), could represent an attractive solution. The active transport activity of such a system was recently demonstrated. In addition, endocrine functions of the cells, such as vitamin D activation, are relevant. The organic anion transporter 1 (OAT-1) overexpressing ciPTEC line presented 1α-hydroxylase (CYP27B1), 24-hydroxylase (CYP24A1) and vitamin D receptor (VDR), responsible for vitamin D activation, degradation and function, respectively. The ability to produce and secrete 1α,25-dihydroxy-vitamin D₃, was shown after incubation with the precursor, 25-hydroxy-vitamin D₃. The beneficial effect of vitamin D on cell function and behavior in uremic conditions was studied in the presence of an anionic uremic toxins mixture. Vitamin D could restore cell viability, and inflammatory and oxidative status, as shown by cell metabolic activity, interleukin-6 (IL-6) levels and reactive oxygen species (ROS) production, respectively. Finally, vitamin D restored transepithelial barrier function, as evidenced by decreased inulin-FITC leakage in biofunctionalized hollow fiber membranes (HFM) carrying ciPTEC-OAT1. In conclusion, the protective effects of vitamin D in uremic conditions and proven ciPTEC-OAT1 endocrine function encourage the use of these cells for BAK application.

Longitudinal changes in serum 25-hydroxyvitamin D in the Dallas Heart Study

CONTEXT

While the prevalence of vitamin D deficiency is well described in various populations, limited data are available regarding longitudinal variation in serum 25-hydroxyvitamin D concentrations.

OBJECTIVES

To evaluate the temporal trends in serum 25(OH)D, prevalence of vitamin D deficiency and factors influencing these trends.

PARTICIPANTS, DESIGN AND SETTING

Adults enrolled in the Dallas Heart Study, a longitudinal, probability-based, multiethnic, population study in Dallas, Texas, USA.

MAIN OUTCOME MEASURES

Prevalence of vitamin D deficiency and predictors of change in serum 25(OH)D.

RESULTS

A total of 2045 participants had serum 25(OH)D measured on two occasions (2000-2002 and 2007-2009) at a median interval of 7 years. Serum 25(OH)D decreased (42.7-39.4 nmol/L, P<.001) and the prevalence of vitamin D deficiency [25(OH)D <50 nmol/L] increased significantly (60.6%-66.4%, P<.0001) despite vitamin D supplementation increasing over the interval (7.2%-23.0%; P<.0001). In a multivariable model adjusting for sex, race, BMI, age, season of blood draw, smoking and exercise, a greater decline in serum 25(OH)D was noted in men compared with women (-8.0 vs -3.5 nmol/L, P<.0001), in participants of Hispanic ethnicity vs White and Black ethnicity (P<.0001), in nonobese vs obese participants (-7.2 vs -4.0 nmol/L, P=.005) and in nonusers vs users of vitamin D supplements (-5.7 vs -1.7 nmol/L, P=.032).

CONCLUSIONS

Despite increased vitamin D supplementation, serum 25(OH)D decreased in an ethnically diverse cohort of Dallas County residents between 2000-2002 and 2007-2009. Features most predictive of a decline in serum 25(OH)D include male sex, Hispanic ethnicity and weight gain.

Link between community-acquired pneumonia and vitamin D levels in older patients

PURPOSE

To investigate the correlation between the level of 25-hydroxyvitamin D [25-(OH)D] and community-acquired pneumonia (CAP) in elderly patients.

METHODS

A total of 163 older patients were chosen from those hospitalized between October 2011 and October 2012. Patients were divided into pneumonia and non-pneumonia groups, and the concentrations of 25-(OH)D (nmol/L) in serum were measured. Clinical data were then compared between the two groups and pneumonia-related risk factors were analyzed using logistic regression.

RESULTS

Among the 163 older hospitalized patients, 49 suffered from pneumonia. Levels of 25-(OH)D, total cholesterol (TC), and low-density lipoprotein cholesterol (LDL-C) were lower (P < 0.05) in the pneumonia group, while severe vitamin D (VitD) deficiency was higher in the pneumonia group (71.4 vs. 19.3%; P < 0.0001). Age and number of hospitalization days were higher in the pneumonia group (P < 0.05). Multivariate logistic regression showed that age and VitD levels were independent risk factors for pneumonia. No significant difference was observed in terms of gender, onset season, body mass index, or smoking and drinking history between the two groups (P > 0.05).

CONCLUSION

The older patients with CAP had a severe VitD deficiency, indicating that low levels of VitD might play an important role in the occurrence and development of CAP.

Impact of vitamin D replacement in adults and elderly in the Middle East and North Africa: a systematic review and meta-analysis of randomized controlled trials

In the Middle East and North Africa (MENA), a vitamin D dose ≥2000 IU/day may be needed to allow to the majority of the population to reach the target 25-hydroxyvitamin D (25(OH)D) level ≥20 ng/ml. Data in the region on the effect of vitamin D supplementation on various skeletal and extra-skeletal effects are scarce.

INTRODUCTION

Hypovitaminosis D is prevalent worldwide, more so in the Middle East and North Africa (MENA). This study aims to determine the effects of vitamin D replacement on the mean difference in 25-hydroxyvitamin D [25(OH)D] level reached and other outcomes, in the MENA.

METHODS

This is a meta-analysis of randomized trials from the MENA, administering vitamin D supplementation for at least 3 months, without language or time restriction. We conducted a comprehensive search in seven databases until July 2015. We abstracted data from published reports, independently and in duplicate. We calculated the mean difference (MD) and 95 % CI of 25(OH)D level reached for eligible comparisons, and pooled data using RevMan version 5.3.

RESULTS

We identified 2 studies in elderly and 17 in adults; for the latter, 11 were included in the meta-analysis. Comparing a high vitamin D dose (>2000 IU/day) to placebo (nine studies), the MD in 25(OH)D level achieved was 18.3 (CI 14.1; 22.5) ng/ml; p value < 0.001; I ² = 92 %. Comparing an intermediate dose (800-2000 IU/day) to placebo (two studies), the MD in 25(OH)D level achieved was 14.7 (CI 4.6; 24.9) ng/ml; p value 0.004; I ² = 91 %. Accordingly, 89 and 71 % of participants, in the high and intermediate dose groups, respectively, reached the desirable level of 20 ng/ml. The risk of bias in the included studies was unclear to high, except for three studies.

CONCLUSION

In the MENA region, vitamin D doses ≥2000 IU/day may be needed to reach the target 25(OH)D level ≥20 ng/ml. The long-term safety and the efficacy of such doses on various outcomes are unknown.

Response of Vitamin D Concentration to Vitamin D3 Administration in Older Adults without Sun Exposure: A Randomized Double-Blind Trial

OBJECTIVES

To determine the dose-response relationship between 25-hydroxyvitamin D (25(OH)D) and supplemental vitamin D3 in elderly nursing home residents.

DESIGN

Randomized double-blind investigation.

SETTING

Nursing home.

PARTICIPANTS

Of 81 women (n=51) and men (n=30) (mean age 87.4±8) enrolled, 72 completed the study.

INTERVENTION

Sixteen weeks of oral vitamin D3 at 800, 2,000, or 4,000 IU/d or 50,000 IU/wk.

MEASUREMENTS

The main outcome was 25(OH)D concentrations (tandem mass spectrometry) after 16 weeks. Free 25(OH)D and intact parathyroid hormone (iPTH) were also analyzed. Safety monitoring of calcium and estimated glomerular filtration rate was performed, and adherence and clinical status were measured.

RESULTS

25(OH)D concentrations increased with dose (P<.001) and were higher with 50,000 IU/wk (P<.001) than other doses and with 4,000 IU/d than 800 or 2,000 IU/d, but 800 IU and 2,000 IU/d did not differ. One subject receiving 800 IU/d had concentrations less than 20 ng/mL. All subjects receiving more than 2000 IU/d had concentrations of 20 ng/mL and greater. Free 25(OH)D concentrations rose with total 25(OH) vitamin D. Total and free 25(OH)D were related to calcium concentrations; only free 25(OH)D was related to iPTH.

CONCLUSION

25(OH)D increased linearly with 800 to 4,000 IU/d and 50,000 IU/wk of vitamin D3, without a ceiling effect. Data suggest that some elderly adults will require more than 800 IU/d of vitamin D3 to ensure adequate vitamin D levels. Changes in 25(OH)D with vitamin D3 were related to starting concentrations (greatest with the lowest concentrations and unchanged with 800 and 2,000 IU/d if 20-40 ng/mL). Relationships between serum calcium and iPTH and free 25(OH)D suggest the potential for free 25(OH)D in defining optimal 25(OH)D concentrations.

Changes of 25-OH-Vitamin D during Overwintering at the German Antarctic Stations Neumayer II and III

Purpose

Humans in Antarctica face different environmental challenges, such as low ultra-violet radiation, which is crucial for vitamin D production in humans. Therefore we assessed changes in 25-OH-vitamin D serum concentration during 13 months of overwintering at the German Stations Neumayer II and III (2007–2012). We hypothesized that (i) 25-OH-vitamin D serum concentration would significantly decrease, (ii) changes would be affected by age, gender, baseline (i.e. pre-overwintering) fat mass, baseline 25-OH-vitamin D serum concentration, and station residence, and (iii) our results would not differ from similar previous studies in comparable high latitudes.

Materials & Methods

25-OH-vitamin D serum concentrations were determined before, after, and monthly during the campaigns from venous blood samples of n = 43 participants (28 men, 15 women). Baseline fat mass was determined via bio impedance analysis and body plethysmography. Data were analyzed for change over time, dependency on independent parameters, and after categorization for sufficiency (>50nmol/l), insufficiency (25-50nmol/l), and deficiency (<25nmol/l). Results were compared with data from similar previous studies.

Results

We found a significant decrease of 25-OH-vitamin D with dependency on month. Age, gender, fat mass, and station residence had no influence. Only baseline 25-OH-vitamin D serum concentrations significantly affected subsequent 25-OH-vitamin D values.

Conclusions

Overwinterings at the Antarctic German research stations Neumayer II and III are associated with a decrease in 25-OH-vitamin D serum concentrations, unaffected by age, gender, baseline fat mass, and station residence. Higher baseline vitamin D serum concentrations might protect from subsequent deficiencies. Residence at the Neumayer Stations may lead to lower vitamin D serum concentrations than found in other comparable high latitudes.

High prevalence of vitamin D deficiency and lack of association with subclinical atherosclerosis in asymptomatic patients with Type 1 Diabetes Mellitus from a Mediterranean area

AIMS

Several studies linked vitamin D deficiency with coronary artery disease (CAD). The aim of this study was to evaluate the relationship between the concentrations of 25-hydroxyvitamin D (25OHD) and the presence of early atherosclerosis in asymptomatic Type 1 Diabetes (T1D) patients with no previous history of ischemic heart disease.

METHODS

One hundred and forty-five patients with T1D (age 37.8 ± 8 years, 57 % male, all Caucasian, disease duration 20.6 ± 8.3 years, HbA1c 7.6 ± 1.4 % (60.2 ± 11.1 mmol/mol), body mass index (BMI) 25.2 ± 3.5 kg/m2, 52.4 % smokers, 23 % retinopathy, 10 % nephropathy) and 48 controls matched for age, sex, BMI and smoking habit were studied. 25OHD deficiency was defined for values ≤20 ng/mL. A sun exposure questionnaire, carotid ultrasonography to determine carotid intima-media thickness (CIMT) and the presence of atheroma plaques and cardiac computed tomography for evaluation of calcium artery calcification (CACS) were performed.

RESULTS

T1D subjects showed a high proportion of 25OHD deficiency (43.2 % vs. 21.7 %, p = 0.032). Of all, 82 % of T1D patients and 92 % of controls had a calcium score of 0. CIMT was greater in patients with T1D (0.55 ± 0.14 mm vs 0.48 ± 0.15, p = 0.01) compared with controls. T1D subjects showed no differences in the results of CACS or CIMT according to the vitamin D concentrations.

CONCLUSIONS

T1D patients have lower concentrations and twice more prevalence of 25OHD deficiency than controls. There was no association between 25OHD concentrations and subclinical CAD.

Vitamin D deficiency is an independent risk factor for urinary tract infections after renal transplants

Vitamin D deficiency is frequently found in patients with renal transplants (RTxs). Because vitamin D plays indispensable roles in the immune system, there may be an association between vitamin D deficiency and infection in these patients, but this has not been fully elucidated. Therefore, this study investigated the impact of pre-RTx vitamin D deficiency on urinary tract infection (UTI) development after RTx.We measured 25-hydroxyvitamin D3 (25(OH)D3) levels in 410 patients 2 weeks before they underwent RTx. Vitamin D deficiency was defined as 25(OH)D3 <10 ng/mL. The primary outcome was UTI occurrence after RTx. Cox proportional hazard analysis determined whether vitamin D deficiency was independently associated with UTI.The mean 25(OH)D3 level was 12.8 ± 6.9 ng/mL, and 171 patients (41.7%) were vitamin D deficient. During a median follow-up duration of 7.3 years, the UTI incidence was significantly higher in vitamin D-deficient patients (52 patients, 30.4%) compared with vitamin D-nondeficient patients (40 patients, 16.7%) (P = 0.001). Moreover, multivariate Cox proportional hazard analysis showed that vitamin D deficiency was an independent predictor of UTI after RTx (hazard ratio 1.81, 95% confidence interval 1.11-2.97, P = 0.02).Vitamin D deficiency was an independent risk factor for UTI after RTx; hence, determining 25(OH)D3 levels might help to predict infectious complications after RTx.

Relationship of vitamin D, HIV, HIV treatment, and lipid levels in the Women's Interagency HIV Study of HIV-infected and uninfected women in the United States

Relationships between vitamin D, lipids, HIV infection, and HIV treatment (±antiretroviral therapy [ART]) were investigated with Women's Interagency HIV Study data (n = 1758 middle-aged women) using multivariable regression. Sixty-three percent of women had vitamin D deficiency. Median 25-hydroxyvitamin D (25-OH vitamin D) was highest in HIV-infected + ART-treated women (17 ng/mL; P < .001) and was the same in HIV-uninfected or HIV-infected women without ART (14 ng/mL). Vitamin D levels were lower if efavirenz (EFV) was included in ART (15 versus 19 ng/mL; P < .001). The most common lipid abnormality was high triglycerides (≥200 mg/dL) in HIV-infected + ART-treated women (13% versus 7% of HIV-infected without ART and 5% of HIV-uninfected; P < .001), with a positive relationship between 25-OH vitamin D and triglycerides (95% confidence interval 0.32-1.69; P < .01). No relationships between 25-OH vitamin D and cholesterol were detected. Vitamin D deficiency is common irrespective of HIV status but influenced by HIV treatment. Similarly, vitamin D levels were positively related to triglycerides only in ART-treated HIV-infected women and unrelated to cholesterol.

Vitamin D deficiency impacts on expression of toll-like receptor-2 and cytokine profile: a pilot study

Background

Vitamin D is believed to play an important role outside the endocrine system in the regulation of the immune system, and in cellular proliferation and differentiation. The aim of the study was to investigate the impact of vitamin D levels on innate immunity.

Methods

Participants for this prospective, longitudinal study were recruited amongst otherwise healthy staff of a large hospital in Victoria, Australia. Those fulfilling the inclusion criteria, including a vitamin D level of <50 nmol/L, were supplemented. Using flow cytometry, expression of the innate immune receptors TLR2, TLR4 and CD86 was measured on peripheral blood mononuclear cells (PBMCs) collected prior to vitamin D treatment and then at 1 and 3 months. Additonally, PBMCs at each timepoint were stimulated with specific TLR ligands and resultant supernatants were assayed for the cytokines TNFα, IL-6, IFN-α and IP-10.

Results

In participants whose vitamin D level was >100 nmol/L post supplementation (n=11), TLR2 expression on PBMCs increased significantly, with no change noted in TLR4 or CD86 expression. Stimulation of vitamin D deficient samples with TLR ligands produced a number of proinflammatory cytokines, which were significantly reduced upon vitamin D normalisation. In patients whose levels returned to a deficient level at 3 months despite ongoing low-level supplementation, an increase in the pro-inflamamtory state returned. This suggests that vitamin D may play an important role in ensuring an appropriate baseline pro-inflammatory state.

Conclusions

This ex-vivo pilot study adds clinical evidence supporting a possibly important role for vitamin D in innate immunity. If confirmed, this unique clinical study has potentially significant implications for the treatment of a variety of inflammatory conditions, where achieving optimal vitamin D levels may help reduce inflammation.

Vitamin D receptor activation and cardiovascular disease

Vitamin D has been recently associated with several renal, cardiovascular and inflammatory diseases, beyond mineral metabolism and bone health. This is due in part to widespread expression of vitamin D receptor (VDR) on tissues and cells such as heart, kidney, immune cells, brain and muscle. In chronic kidney disease (CKD) and other chronic disorders, vitamin D deficiency [serum 25(OH)D <20 ng/mL] is very common and is associated with adverse outcomes. Paricalcitol, a selective activator of VDR, has demonstrated in several experimental and clinical studies of diabetic and non-diabetic CKD a favourable profile compared to other VDR activators, alone or as add-on to standard therapy. These beneficial effects are mediated by different actions such as reduction of oxidative stress, inflammation, downregulation of cardiac and renal renin expression, downregulation of calcifying genes and direct vascular protective effects. Furthermore, paricalcitol beneficial effects may be independent of baseline serum parathyroid hormone (PTH), calcium and phosphate levels. These benefits should be confirmed in large and well-designed ongoing clinical trials.

The risk of all-cause mortality is inversely related to serum 25(OH)D levels

CONTEXT AND OBJECTIVES

Vitamin D plays a key role in maintaining bone health, but evidence for its nonskeletal effects is inconsistent. This study aims to examine the association between serum 25-hydroxyvitamin D [25(OH)D] levels and all-cause mortality in a large general population cohort.

DESIGN, PARTICIPANTS, AND SETTING

Using the computerized database of the largest health care provider in Israel, we identified a cohort of subjects 20 years old or older with serum 25(OH)D levels measured between January 2008 and December 2009. Vital status was ascertained through August 2011.

RESULTS

Median follow-up was 28.5 months (interquartile range 23.8-33.5 months); 7,247 of 182,152 participants (4.0%) died. Subjects who died had significantly lower serum 25(OH)D levels (mean 44.8 ± 24.2 nmol/liter) than those alive at the end of follow-up (51.0 ± 23.2 nmol/liter), P < 0.001. After adjustment for age, gender, ethnicity, and seasonality, the hazard ratio (HR) for all-cause mortality was 2.02 [95% confidence interval (CI) 1.89-2.15] for the lowest serum 25(OH)D quartile (<33.8 nmol/liter) compared with the highest. After further adjustment for comorbidity, use of vitamin D supplements and statins, smoking, socioeconomic status, and body mass index, the HR was 1.81 (95% CI 1.69-1.95). This remained, even after adjustment for serum low-density lipoprotein, high-density lipoprotein, calcium level (corrected for serum albumin levels), and glomerular filtration rate, 1.85 (95% CI 1.70-2.01). The fully adjusted HR associated with being in the second 25(OH)D quartile (33.8-49.4 nmol/liter) was 1.25 (95% CI 1.16-1.34).

CONCLUSIONS

All-cause mortality is independently and inversely associated with serum 25(OH)D levels at levels less than 50 nmol/liter.

The immunoregulatory function of vitamin D: implications in chronic kidney disease

Cardiovascular and infectious diseases remain the most common causes of death among patients with chronic kidney disease (CKD) and end-stage renal disease (ESRD). Basic science and epidemiological studies indicate that vitamin D has importance not only for cardiovascular health, but also for the immune response. Vitamin D signaling pathways regulate both innate and adaptive immunity, maintaining the associated inflammatory response within physiological limits. Levels of both the inactive as well as active form of vitamin D (25-hydroxyvitamin D and 1,25-dihydroxyvitamin D, respectively) are decreased in patients with CKD and ESRD. It is reasonable to hypothesize, therefore, that the immune dysfunction associated with vitamin D deficiency in patients with CKD and ESRD in part explains the misdirected inflammatory response and increased susceptibility to infection seen in this population. Indeed, observational studies show that vitamin D deficiency in patients with ESRD is associated with increased mortality, and treatment with vitamin D is associated with a decreased risk of infection, as well as reduced all-cause mortality. However, whether different vitamin D preparations have differential effects on physiological function and clinical outcomes is still unclear. A proper understanding of the immune regulatory function of vitamin D is important for the development of future therapeutic strategies.

Vitamin D supplementation did not prevent influenza-like illness as diagnosed retrospectively by questionnaires in subjects participating in randomized clinical trials

BACKGROUND

Vitamin D deficiency has been associated with a number of diseases, including influenza. Whether or not this reflects a causal relationship is unknown. We therefore wanted to examine if supplementation with vitamin D would affect the incidence and severity of influenza-like disease.

METHODS

Questionnaires on influenza were sent to subjects participating in ongoing placebo-controlled intervention studies with vitamin D supplementation, up until the end of April 2010.

RESULTS

Five hundred and sixty-nine subjects from 10 different clinical trials were included in the study, of whom 289 were randomized to receive vitamin D (1111-6800 IU/day) and 280 to receive placebo. Influenza-like disease during the previous fall/winter was reported in 38 subjects in the vitamin D group and 42 in the placebo group (non-significant), of whom 25 and 26 subjects, respectively, fulfilled our clinical criteria for influenza. In these latter subjects, the duration of illness was significantly longer among those in the vitamin D group than among those in the placebo group (median 7 (range 2-60) days vs median 4 (range 2-18) days; p = 0.007). However, this difference was not statistically significant if all 38 (vitamin D) and 42 (placebo) subjects who reported symptoms were included.

CONCLUSION

Our results do not support the hypothesis that high doses of vitamin D supplementation will have a pronounced effect on influenza-like disease in populations not targeted for high influenza risk.

Vitamin D deficiency in HIV-infected and HIV-uninfected women in the United States

BACKGROUND

Vitamin D deficiency is of increasing concern in HIV-infected persons because of its reported association with a number of negative health outcomes that are common in HIV. We undertook this study to determine the prevalence and predictors of vitamin D deficiency among a nationally representative cohort of middle-aged, ethnically diverse, HIV-infected and HIV-uninfected women enrolled in the Women's Interagency HIV Study (WIHS).

METHODS

Vitamin D testing was performed by Quest Diagnostics on frozen sera using the liquid chromatography/mass spectroscopy method. Vitamin D deficiency was defined as 25(OH)D ≤20 ng/mL. Comparisons of continuous and categorical characteristics among HIV-infected and HIV-uninfected women were made by Wilcoxon tests and Pearson χ tests, respectively.

RESULTS

One thousand seven hundred seventy-eight women (1268 HIV positive) were studied. Sixty-three percent had vitamin D deficiency (60% HIV positive vs. 72% HIV negative; P < 0.001). Multivariable predictors of vitamin D deficiency were being African American (adjusted odds ratio 3.02), Hispanic (adjusted odds ratio 1.40), body mass index (adjusted odds ratio 1.43), age (adjusted odds ratio 0.84), HIV positive (adjusted odds ratio 0.76), glomerular filtration rate <90·mL·min (adjusted odds ratio 0.94), and WIHS sites Los Angeles (adjusted odds ratio 0.66) and Chicago (adjusted odds ratio 0.63). In the HIV-positive women, multivariate predictors were undetectable HIV RNA (adjusted odds ratio 0.69), CD4 50-200 cells per cubic millimeter (adjusted odds ratio 1.60), CD4 <50 cells per cubic millimeter (adjusted odds ratio 1.94), and recent protease inhibitor use (adjusted odds ratio 0.67).

CONCLUSIONS

In this study of more than 1700 women in the United States, most women with or without HIV infection had low vitamin D levels and African American women had the highest rates of vitamin D deficiency. An understanding of the role that vitamin D deficiency plays in non-AIDS-related morbidities is planned for investigation in WIHS.

Vitamin d, and kidney disease

Mineral metabolism abnormalities, such as low 1,25-dihydroxyvitamin D (1,25(OH)(2)D) and elevated parathyroid hormone (PTH), are common at even higher glomerular filtration rate than previously described. Levels of 25-hydroxyvitamin D (25(OH)D) show an inverse correlation with those of intact PTH and phosphorus. Studies of the general population found much higher all-cause and cardiovascular (CV) mortality for patients with lower levels of vitamin D; this finding suggests that low 25(OH)D level is a risk factor and predictive of CV events in patients without chronic kidney disease (CKD). 25(OH)D/1,25(OH)2D becomes deficient with progression of CKD. Additionally, studies of dialysis patients have found an association of vitamin D deficiency with increased mortality. Restoration of the physiology of vitamin D receptor activation should be essential therapy for CKD patients.

[Vitamin D and hypertension]

Low levels of vitamin D, defined as levels of 25-hydroxyvitamin D < 20-30 ng/ml, is a prevalent problem in the general population. Besides the classic relation with musculoskeletal disease, vitamin D has been also related to autoimmune diseases, cancer, metabolic diseases or cardiovascular diseases. High blood pressure, as the main cardiovascular risk factor, also has been related to vitamin D deficiency, constituting two prevalent worldwide health problems. Therefore, this article reviews the most important studies that combine both pathologies, the biological mechanism that relate them and the current evidence about the effect of vitamin D supplementation on hypertension.

Vitamin D and metabolic health with special reference to the effect of vitamin D on serum lipids

Considering that the vitamin D receptor as well as the 1-α-hydroxylase enzyme that converts 25-hydroxyvitamin D (25(OH)D) to its active form 1,25-dihydroxyvitamin D have been found in tissues throughout the body, it is likely that vitamin D is important for more than the calcium balance. Accordingly, low serum levels of 25(OH)D have been associated with mortality, cardiovascular disease, type 2 diabetes, hypertension and obesity. Low serum levels of 25(OH)D have also been associated with an unfavourable lipid profile, which could possible explain the relation with cardiovascular disease and mortality. However, the relation between vitamin D and lipids have so far received little attention and is therefore the main focus of the present review. A PubMed search identified 22 cross-sectional studies where serum levels of 25(OH)D and lipids were related and that included a minimum of 500 subjects, and 10 placebo-controlled double-blind intervention studies with vitamin D where more than 50 subjects were included. In all the cross-sectional studies serum 25(OH)D was positively associated with high-density lipoprotein cholesterol (HDL-C) resulting in a favourable low-density lipoprotein cholesterol (LDL-C) (or total cholesterol) to HDL-C ratio. There was also a uniform agreement between studies on a negative relation between serum 25(OH)D and triglycerides (TG). On the other hand, the intervention studies gave divergent results, with some showing a positive and some a negative effect of vitamin D supplementation. However, none of the intervention studies were specifically designed for evaluating the relation between vitamin D and lipids, none had hyperlipemia as an inclusion criterion, and none were sufficiently powered. In only one study was a significant effect seen with an 8% (0.28 mmol/L) increase in serum LDL-C and a 16% (0.22 mmol/L) decrease in serum TG in those given vitamin D as compared to the placebo group. Accordingly, the effect of vitamin D supplementation on serum lipids is at present uncertain. Considering the numerous other promising vitamins and minerals that when properly tested have been disappointing, one should wait for the results of forthcoming vitamin D intervention studies before drawing conclusions on potential beneficial effects of vitamin D.

Vitamin D and cardiovascular disease: systematic review and meta-analysis of prospective studies

BACKGROUND

Low serum 25-hydroxyvitamin D (25-OH-D) has recently been linked to cardiovascular diseases. This review summarizes evidence from prospective studies evaluating the prognostic value of 25-OH-D for cardiovascular disease incidence and mortality.

METHOD

A systematic literature search in EMBASE and Pubmed-Medline databases was performed until November 2009. Prospective studies published in English were selected reporting estimates for the association of 25-OH-D with primary or secondary cardiovascular event incidence or mortality in the general population or subjects with prevalent cardiovascular disease. Pooled risk estimators were derived by meta-analysis using a random effects model approach.

RESULTS

Four incidence and five independent mortality studies were included. Two incidence and three mortality studies reported a two- to five-fold risk increase for both outcomes in subjects with lower 25-OH-D, while the others did not detect a significant association. Meta-analysis supported the existence of an inverse association.

CONCLUSION

Data from prospective investigations suggest an inverse association between 25-OH-D and cardiovascular risk. However, given the heterogeneity and small number of longitudinal studies, more research is needed to corroborate a potential prognostic value of 25-OH-D for cardiovascular disease incidence and mortality.

Serum vitamin D and risk of secondary cardiovascular disease events in patients with stable coronary heart disease

BACKGROUND

Recent longitudinal analyses suggested that low levels of serum 25-hydroxyvitamin D (25-OH-D) predict incident cardiovascular disease in initially healthy populations. Because the prognostic value of vitamin D for the occurrence of secondary cardiovascular events remains unclear, we examined the association of baseline 25-OH-D levels with prognosis in patients with stable coronary heart disease (CHD).

METHODS

Serum 25-OH-D levels from 1,125 CHD patients of 2 German clinics undergoing a 3-week rehabilitation program after an acute cardiovascular event were measured, and participants were followed for up to 8 years. We used multivariate Cox regression analysis to model cardiovascular event incidence (fatal and nonfatal, including myocardial infarction, stroke, and death due to cardiovascular diseases) and all-cause mortality according to 25-OH-D quartiles, categories based on cut points of 15 and 30 ng/mL, or continuous vitamin D concentrations.

RESULTS

During follow-up, 148 cardiovascular events and 121 deaths were recorded. Elevation of risk for the lowest quartile or category in comparison to the highest category was weak and nonsignificant for both incidence (hazard ratio [HR](quartile1) = 1.15 [0.72-1.84], HR(<15 ng/mL) = 1.17 [0.61-2.23]) and mortality (HR(quartile1) = 1.29 [0.77-2.14], HR(<15 ng/mL) = 1.87 [0.91-3.82]) in unadjusted Cox regression analysis and disappeared entirely after adjustment for potential confounders (cardiovascular events: HR(quartile1) = 0.84 [0.47-1.50], HR(<15 ng/mL) = 0.90 [0.41-1.96]; mortality: HR(quartile1) = 0.63 [0.33-1.21], HR(<15 ng/mL) = 0.93 [0.39-2.21]). Models treating vitamin D as a continuous variable likewise suggested no significant associations.

CONCLUSIONS

Unlike previous population-based studies, our analysis in high-risk patients with stable CHD does not support a prognostic value of baseline-25-OH-D levels for secondary cardiovascular event incidence or all-cause mortality.

Low serum 25-hydroxyvitamin D levels are associated with increased all-cause mortality risk in a general population: the Tromsø study

OBJECTIVE

Ecologic and observational studies have suggested an association between serum 25-hydroxyvitamin D (25(OH)D) levels and cardiovascular disease (CVD) risk factors, CVD mortality, and cancer mortality. Based on this, low serum 25(OH)D levels should be associated with higher all-cause mortality in a general population. This hypothesis was tested in the present study.

DESIGN

The Tromsø study is a longitudinal population-based multipurpose study initiated in 1974 with focus on lifestyle-related diseases. Our data are based on the fourth Tromsø study carried out in 1994-1995.

METHODS

Information about death and cause of death was registered by obtaining information from the National Directory of Residents and the Death Cause Registry. Serum 25(OH)D was measured in 7161 participants in the fourth Tromsø study. Results are presented for smokers (n=2410) and non-smokers (n=4751) separately as our immunoassay seems to overestimate 25(OH)D levels for smokers.

RESULTS

During a mean 11.7 years of follow-up, 1359 (19.0%) participants died. In multivariate regression models, there was a significantly increased risk of all-cause mortality (hazard ratio (HR) 1.32, confidence interval (CI) 1.07-1.62) among non-smoking participants in the lowest 25(OH)D quartile when compared with participants in the highest quartile. Equivalent results for smokers were not significant (HR 1.06, CI 0.83-1.35).

CONCLUSIONS

Low serum 25(OH)D levels were associated with increased all-cause mortality for non-smokers, but the results did not reach statistical significance for smokers. However, low 25(OH)D levels are known to be associated with impaired general health, and randomized controlled studies are needed to address the question of causality.

Vitamin D status during pregnancy and aspects of offspring health

Low maternal vitamin D levels during pregnancy have been linked to various health outcomes in the offspring, ranging from periconceptional effects to diseases of adult onset. Maternal and infant cord 25(OH)D levels are highly correlated. Here, we review the available evidence for these adverse health effects. Most of the evidence has arisen from observational epidemiological studies, but randomized controlled trials are now underway. The evidence to date supports that women should be monitored and treated for vitamin D deficiency during pregnancy but optimal and upper limit serum 25(OH)D levels during pregnancy are not known.

Vitamin d and serum cytokines in a randomized clinical trial

Background. The role of vitamin D in the body's ability to fight influenza and URI's may be dependent on regulation of specific cytokines that participate in the host inflammatory response. The aim of this study was to test the hypothesis that vitamin D can influence intracellular signaling to regulate the production of cytokines. Subjects and Methods. This study was a 3-month prospective placebo-controlled trial of vitamin D3 supplementation in ambulatory adults [Li-Ng et al., 2009]. 162 volunteers were randomized to receive either 50 μg/d (2000 IU) of vitamin D3 or matching placebo. 25(OH)D and the levels of 10 different cytokines (IL-2, 4, 5, 6, 8, 10, 13, GM-CSF, IFN-γ, TNF-α) were measured in the serum of participants at baseline and the final visit. There were 6 drop-outs from the active vitamin D group and 8 from the placebo group. Results. In the active vitamin D group, we found a significant median percent decline in levels of GM-CSF (-62.9%, P < .0001), IFN-γ (-38.9%, P < .0001), IL-4 (-50.8%, P = .001), IL-8 (-48.4%, P < .0001), and IL-10 (-70.4%, P < .0001). In the placebo group, there were significant declines for GM-CSF (-53.2%, P = .0007) and IFN-γ (-34.4%, P = .0011). For each cytokine, there was no significant difference in the rate of decline between the two groups. 25(OH)D levels increased in the active vitamin D group from a mean of 64.3 ± 25.4 nmol/L to 88.5 ± 23.2 nmol/L. Conclusions. The present study did not show that vitamin D3 supplementation changed circulating cytokine levels among healthy adults.

Vitamin D, proteinuria, diabetic nephropathy, and progression of CKD

Although the endocrine effects of vitamin D are widely recognized, somewhat less appreciated is that vitamin D may serve paracrine functions through local activation by 1-alpha-hydroxylase and thus maintain immunity, vascular function, cardiomyocyte health, and abrogate inflammation and insulin resistance. In the kidney, vitamin D may be important for maintaining podocyte health, preventing epithelial-to-mesenchymal transformation, and suppressing renin gene expression and inflammation. Replacement with pharmacologic dosages of vitamin D receptor agonists (VDRA) in animal models of kidney disease consistently show reduction in albuminuria, abrogation of glomerulosclerosis, glomerulomegaly, and glomerular inflammation, effects that may be independent of BP and parathyroid hormone, but the effects of VDRA in preventing tubulointerstitial fibrosis and preventing the progression of kidney failure in these animal models are less clear. Emerging evidence in patients with chronic kidney disease (CKD) show that vitamin D can reduce proteinuria or albuminuria even in the presence of angiotensin-converting enzyme inhibition. In addition to reducing proteinuria, VDRA may reduce insulin resistance, BP, and inflammation and preserve podocyte loss providing biologic plausibility to the notion that the use of VDRA may be associated with salubrious outcomes in patients with diabetic nephropathy. Patients with CKD have a very high prevalence of deficiency of 25-hydroxyvitamin D. Whether pharmacologic dosages of vitamin D instead of VDRA in patients with CKD can overcome the paracrine and endocrine functions of this vitamin remains unknown. To demonstrate the putative benefits of native vitamin D and VDRA among patients with CKD, randomized, controlled trials are needed.