The "sunshine deficit" and cardiovascular disease

UV radiation and air pollution as drivers of major autoimmune conditions

Autoimmune diseases comprise a very heterogeneous group of disorders characterized by disruptive immune responses against self-antigens, chronic morbidity and increased mortality. The incidence and prevalence of major autoimmune conditions are particularly high in the western world, at northern latitudes, and in industrialized countries. This study will mainly focus on five major autoimmune conditions, namely type 1 diabetes, multiple sclerosis, inflammatory bowel diseases, rheumatoid arthritis, and autoimmune thyroid disorders. Epidemiological and experimental evidence suggests a protective role of sunlight exposure on the etiology of major autoimmune conditions mediated by the endogenous production of vitamin D and nitric oxide. A historical perspective shows how the rise of anthropogenic air pollutants is temporally associated with dramatic increases in incidence of these conditions. The scattering caused by ambient particulate matter and the presence of tropospheric ozone can reduce the endogenous production of vitamin D and nitric oxide, which are implicated in maintaining the immune homeostasis. Air pollutants have direct detrimental effects on the human body and are deemed responsible of an increasingly higher portion of the annual burden of human morbidity and mortality. Air pollution contributes in systemic inflammation, activates oxidative pathways, induces epigenetic alterations, and modulates the function and phenotype of dendritic cells, Tregs, and T-cells. In this review, we provide epidemiological and mechanistic insights regarding the role of UV-mediated effects in immunity and how anthropic-derived air pollution may affect major autoimmune conditions through direct and indirect mechanisms.

Association between serum 25-hydroxyvitamin-D and Triglycerides-Glucose index among Indian adolescents

Background

Vitamin D deficiency has been found to associated with numerous skeletal and non-skeletal diseases including Diabetes Mellitus. Insulin Resistance (IR) is considered as one of the primary reasons of Type-2 Diabetes Mellitus (T2DM). The association between vitamin D deficiency and IR has been extensively explore in previous studies, but none of them focused on Indian adolescents, and none of them used the TyG index as IR marker. Hence, this population-based cross-sectional study investigates the relationship between insulin resistance (IR) assessed using the Triglycerides Glucose Index (TyG index) and vitamin D measured by serum 25-hydroxyvitamin-D (25(OH)D).

Methods

For this study, we utilized data from the Comprehensive National Nutrition Survey (CNNS, 2016–18). The study is based on a sample size of 10,167 adolescents aged 10–19 years. The TyG index cut-off value of 4.65 was used to classify IR. We examined associations between the TyG index and serum 25(OH)D using multiple linear regression models adjusted for potential confounders. Odds of Insulin Resistance among vitamin D deficient/insufficient adolescents were assessed using multivariable logistic regression.

Results

A significant negative association was found between serum 25(OH)D and the TyG index, where a 10% increase in serum 25(OH)D was associated with 0.56 (95% CI = -0.67, -0.45) unit decrement in the TyG index. The odds of having IR were 90% higher among vitamin D deficient adolescents (OR: 1.90; 95% CI = 1.62—2.23) compared to adolescents with adequate levels of vitamin D. The association between vitamin D deficiency and IR was independent of sex; in other words, the association between vitamin D and IR was significant in both the sexes.

Conclusion

Independent of sex, this study found a significant inverse association between vitamin D and insulin resistance in Indian adolescents. The findings of this study highlight the utility of TyG index and the importance of vitamin D in lowering the risk of T2DM in future generations of the country.

L-shaped association of serum 25-hydroxyvitamin D concentrations with cardiovascular and all-cause mortality in individuals with osteoarthritis: results from the NHANES database prospective cohort study

BACKGROUND

The relationship between vitamin D status and mortality in patients with osteoarthritis (OA) is unknown. This study investigated the associations of serum 25-hydroxyvitamin D [25(OH)D] concentrations with all-cause and cause-specific mortality among American adults with OA.

METHODS

This study included 2556 adults with OA from the National Health and Nutrition Examination Survey (2001-2014). Death outcomes were ascertained by linkage to National Death Index (NDI) records through 31 December 2015. Cox proportional hazards model and two-piecewise Cox proportional hazards model were used to elucidate the nonlinear relationship between serum 25(OH)D concentrations and mortality in OA patients, and stratified analyses were performed to identify patients with higher mortality risk.

RESULTS

During 16,606 person-years of follow-up, 438 all-cause deaths occurred, including 74 cardiovascular disease (CVD)-related and 78 cancer deaths. After multivariable adjustment, lower serum 25(OH)D levels were significantly and nonlinearly associated with higher risks of all-cause and CVD mortality among participants with OA. Furthermore, we discovered L-shaped associations between serum 25(OH)D levels and all-cause and CVD mortality, with mortality plateauing at 54.40 nmol/L for all-cause mortality and 27.70 nmol/L for CVD mortality. Compared to participants with 25(OH)D levels below the inflection points, those with higher levels had a 2% lower risk for all-cause mortality (hazard ratio [HR] 0.98, 95% confidence interval [CI] 0.96-0.99) and 17% lower risk for CVD mortality (HR 0.83, 95% CI 0.72-0.95).

CONCLUSIONS

Nonlinear associations of serum 25(OH)D levels with all-cause and CVD mortality were observed in American patients with OA. The thresholds of 27.70 and 54.40 nmol/L for CVD and all-cause mortality, respectively, may represent intervention targets for lowering the risk of premature death and cardiovascular disease, but this needs to be confirmed in large clinical trials.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

LEVEL OF EVIDENCE

V.

Concentration levels of serum 25-Hydroxyvitamin-D and vitamin D deficiency among children and adolescents of India: a descriptive cross-sectional study

Background

Vitamin D is an essential micronutrient for the overall health and well-being of individuals. For strong musculoskeletal and neurological development of human body, vitamin D levels during childhood and adolescence have key importance. This is the first national-level study that analyzes the deficiency and concentration of serum 25-Hydroxyvitamin D [25(OH)D)] among Indian children and adolescents with respect to various demographic and socioeconomic characteristics.

Methods

Data of Comprehensive National Nutrition Survey (CNNS, 2016–18) was utilized for the present study. Vitamin D levels were assessed based on serum 25-hydroxyvitamin D concentration. Prevalence of vitamin D deficiency has been shown for the three age groups: 0–4 years (n = 12,764), 5–9 years (n = 13,482), 10–19 years (n = 13,065). Vitamin D deficiency was defined as: serum 25(OH)D < 12 ng/mL; and insufficiency as: 12 ng/ml ≤ 25(OH) < 20 ng/ml. 25(OH) D level higher than 20 ng/mL was accepted as adequate. Random slope multilevel logistic regression models were employed to assess the demographic and socioeconomic correlates of vitamin D deficiency.

Results

Mean serum 25(OH)D concentration level was found to be 19.51 ± 8.76, 17.73 ± 7.91, and 17.07 ± 8.16 ng/ml in age group 0–4 years, 5–9 years and 10–19 years respectively. 49.12% of the children aged 0–4 years were having insufficient level of vitamin D. Prevalence of vitamin D deficiency was comparatively higher among female adolescents (76.16%), adolescents living in rural region (67.48), Sikh individuals (0–4 years: 76.28%; 5–9 years: 90.26%; 10–19 years: 89.56%), and adolescents coming from rich households. North-Indian individuals were having substantially higher odds of vitamin D deficiency in all the three age groups.

Conclusion

The present study demonstrated that the prevalence of vitamin D deficiency is considerably high among children and adolescents of India. The study highlights high-risk group which require prompt policy interventions.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12887-021-02803-z.

Non-Musculoskeletal Benefits of Vitamin D beyond the Musculoskeletal System

Vitamin D, a fat-soluble prohormone, is endogenously synthesized in response to sunlight or taken from dietary supplements. Since vitamin D receptors are present in most tissues and cells in the body, the mounting understanding of the role of vitamin D in humans indicates that it does not only play an important role in the musculoskeletal system, but has beneficial effects elsewhere as well. This review summarizes the metabolism of vitamin D, the research regarding the possible risk factors leading to vitamin D deficiency, and the relationships between vitamin D deficiency and numerous illnesses, including rickets, osteoporosis and osteomalacia, muscle weakness and falls, autoimmune disorders, infectious diseases, cardiovascular diseases (CVDs), cancers, and neurological disorders. The system-wide effects of vitamin D and the mechanisms of the diseases are also discussed. Although accumulating evidence supports associations of vitamin D deficiency with physical and mental disorders and beneficial effects of vitamin D with health maintenance and disease prevention, there continue to be controversies over the beneficial effects of vitamin D. Thus, more well-designed and statistically powered trials are required to enable the assessment of vitamin D’s role in optimizing health and preventing disease.

Environmental, Nutritional, and Socioeconomic Determinants of IBD Incidence: A Global Ecological Study

BACKGROUND AND AIMS

The wide variation in inflammatory bowel disease [IBD] incidence across countries entails an opportunity to recognise global disease determinants and hypothesise preventive policies.

METHODS

We fitted multivariable models to identify putative environmental, nutritional, and socioeconomic determinants associated with the incidence of IBD (i.e. ulcerative colitis [UC] and Crohn's disease [CD]). We used the latest available country-specific incidence rates, and aggregate data for 20 determinants, from over 50 countries accounting for more than half of the global population. We presented the associations with exponentiated beta coefficients (exp[β]) indicating the relative increase of disease incidence per unit increase in the predictor variables.

RESULTS

Country-specific incidence estimates demonstrate wide variability across the world, with a median of 4.8 new UC cases (interquartile range [IQR] 2.4-9.3), and 3.5 new CD cases [IQR 0.8-5.7] per 100 000 population per year. Latitude (exp[β] 1.05, 95% confidence interval [CI] 1.04‒1.06, per degree increase), prevalence of obesity [1.05, 1.02‒1.07, per 1% increase], and of tobacco smoking [0.97, 0.95‒0.99, per 1% increase] explained 71.5% of UC incidence variation across countries in the adjusted analysis. The model for CD included latitude [1.04, 1.02‒1.06], expenditure for health (1.03, 1.01‒1.05, per 100 purchasing power parity [PPP]/year per capita increase), and physical inactivity prevalence [1.03, 1.00‒1.06, per 1% increase], explaining 58.3% of incidence variation across countries. Besides expenditure for health, these associations were consistent in low/middle- and high-income countries.

CONCLUSIONS

Our analysis highlights factors able to explain a substantial portion of incidence variation across countries. Further high-quality research is warranted to develop global strategies for IBD prevention.

Heart failure and fracture risk: a meta-analysis

This meta-analysis was conducted to investigate whether heart failure is associated with an increased risk of fractures by summarizing all the available evidence. The PubMed, EMBASE, and Cochrane Library databases were searched for all relevant studies published from the date of database inception to April 2018. Studies that investigated the association between heart failure and fracture risk and conducted a comparison with controls were included. Seven cohort studies were finally identified as eligible for inclusion in the meta-analysis. All included studies were of high quality as evaluated by the Newcastle-Ottawa Scale. There was a significantly higher risk of any fracture in patients diagnosed with heart failure (N = 53,038) than in controls (N = 126,727) (RR 1.66, 95% CI 1.14-2.43, I² = 94%, P = 0.008). The results were the same for hip (RR 3.45, 95% CI: 1.86-6.40, I² = 95%, P < 0.0001) and humerus fractures (RR 1.91, 95% CI 1.07-3.40, I² = 39%, P = 0.03) but not for vertebral and forearm fractures. To conclude, this meta-analysis demonstrated that patients with heart failure had an increased risk of fractures, especially hip and humerus fractures. Patients with heart failure may need to pay greater attention to their bone health. This meta-analysis found a significantly higher risk of fractures in patients with heart failure than in those without heart failure. Greater attention should be paid to bone health in patients with heart failure.

Severity of Vitamin D Deficiency Predicts Mortality in Ischemic Stroke Patients

Background

Vitamin D (VD) deficiency is considered an independent risk factor for death due to cardiovascular events including ischemic stroke (IS). We assessed the hypothesis that decreased levels of 25-hydroxyvitamin D (25-OH-D) are associated with increased risk of mortality in patients with IS.

Methods

Serum 25-OH-D, intact parathyroid hormone (iPTH), and intact fibroblast growth factor 23 (iFGF23) levels were assessed in serum of 240 consecutive patients admitted within the 24 hours after the onset of IS. Mortality data was obtained from the local registry office.

Results

Only three subjects (1.3%) had an optimal 25-OH-D level (30-80 ng/mL), 25 (10.4%) had a mildly reduced (insufficient) level, 61 (25.4%) had moderate deficiency, and 151 (62.9%) had a severe VD deficiency. 20% subjects had secondary hyperparathyroidism. The serum 25-OH-D level was significantly lower than that in 480 matched subjects (9.9 ± 7.1 vs. 21.0 ± 8.7 ng/mL). Of all the patients, 79 (32.9%) died during follow-up observation (44.9 months). The mortality rates (per year) were 4.81 and 1.89 in a group with and without severe VD deficiency, respectively (incidence rate ratio: 2.52; 95% CI: 1.44–4.68). There was no effect of secondary hyperparathyroidism and iFGF23 levels on mortality rates. Age, 25 − OH − D < 10 ng/mL, and functional status (modified Rankin scale) were significant factors increasing the risk of death in multivariable Cox proportional hazard regression test.

Conclusions

Severe VD deficiency is an emerging, strong negative predictor for survival after IS, independent of age and functional status. VD supplementation in IS survivals may be considered due to high prevalence of its deficiency. However, it is uncertain whether it will improve their survival.

Vitamin D Supplementation, Serum 25(OH)D Concentrations and Cardiovascular Disease Risk Factors: A Systematic Review and Meta-Analysis

Background: Cardiovascular disease (CVD) risk factors are associated with low serum 25 hydroxyvitamin D (25(OH)D) concentrations in observational studies; however, clinical trial findings are inconsistent.

Objective: We assessed the effect of vitamin D supplementation and increased serum 25(OH)D concentrations on CVD risk factors in a systemic review and meta-analysis of randomized controlled trials (RCTs).

Design: MEDLINE, CINAHL, EMBASE, and Google Scholar were searched for RCTs that evaluated vitamin D supplementation and cardiovascular outcomes [blood pressure, parathyroid hormone (PTH), serum high-sensitivity C-reactive protein (hs-CRP), total cholesterol, high and low density lipoprotein (HDL and LDL, respectively), triglycerides, peak wave velocity (PWV) and Augmentation Index (AI)] from 1992 through 2017. Meta-analysis was based on a random-effects model and inverse variance method to calculate standardized mean difference (SMD) as effect sizes, followed by a leave-one-out method for sensitivity analysis. Risk of publication bias was assessed using Cochrane checklist and Begg funnel plots. The systematic review is registered as CRD42015025346.

Results: We identified 2341 studies from which 81 met inclusion criteria. The meta-analysis indicated a significant reduction in systolic blood pressure (SMD = −0.102 ± 0.04 mmHg, 95% confidence interval (CI), −0.20 to −0.03), diastolic blood pressure (SMD = −0.07 ± 0.03 mmHg, 95% CI, −0.14 to −0.006), serum PTH (SMD = −0.66 ± 0.08 ng/L, 95% CI, −0.82 to −0.49), hs-CRP (SMD = −0.20 ± 0.07 mg/L, 95% CI, −0.34 to −0.06), total cholesterol (SMD = −0.15 ± 0.06 mmol/L, 95% CI, −0.25 to −0.04), LDL (SMD = −0.10 ± 0.05 mmol/L, 95% CI, −0.20 to −0.003), triglycerides (SMD = −0.12 ± 0.06 mmol/L, 95% CI, −0.23 to −0.003) and a significant increase in HDL (SMD = 0.09 ± 0.04 mmol/L, 95% CI, 0.00 to 0.17) with vitamin D supplementation. These findings remained significant in sensitivity analyses for blood pressure, lipid profile, serum PTH, and serum hs-CRP. There was no significant effect of vitamin D supplementation on PWV (SMD = −0.20 ± 0.13 m/s, 95% CI, −0.46 to 0.06, p = 0.14) and AI (SMD = −0.09 ± 0.14%, 95% CI, −0.37 to 0.19, p = 0.52) for vitamin D supplemented groups.

Conclusion: These findings suggest that vitamin D supplementation may act to protect against CVD through improving risk factors, including high blood pressure, elevated PTH, dyslipidemia, and inflammation.

Genetic polymorphisms of vitamin D3 metabolizing CYP24A1 and CYP2R1 enzymes in Turkish patients with ischemic stroke

Objective Vitamin D deficiency is known as an important risk factor in pathogenesis of atherosclerosis, which contributes to stroke development. Genetic variations including single nucleotide polymorphisms (SNPs) in enzymes involved in vitamin D metabolism can affect susceptibility to the development of stroke. Therefore, the objective of this study was to investigate the association between polymorphisms of vitamin D metabolizing enzymes (rs927650 SNP in CYP24A1, and rs10741657 SNP in CYP2R1 genes,) and ischemic stroke risk in Turkish population. Materials and methods To test this hypothesis, we designed a case-control study which consisted of 256 ischemic stroke patients and 132 controls. Genotypes were determined by PCR-RFLP technique. Results No significant differences were found between patients and controls in terms of CYP24A1 rs927650 and CYP2R1 rs10741657 genotype frequencies. Polymorphic allele frequencies of CYP24A1 rs927650 and CYP2R1 rs10741657 were 0.414 and 0.660 in stroke patients, respectively. Conclusion This is the first study conducted regarding the association of CYP24A1 rs927650 and CYP2R1 rs10741657 genetic polymorphisms and ischemic stroke risk. The polymorphic genotypes of these polymorphisms, together with hypertension, diabetes, smoking, and obesity, were found as significant risk factors for ischemic stroke.

Serum vitamin D deficiency and risk of hospitalization for heart failure: Prospective results from the Moli-sani study

BACKGROUND AND AIMS

Evidence indicates that Vitamin D deficiency may be associated with increased risk of cardiovascular disease, although findings on risk of heart failure (HF) are controversial. We investigated the relationship between serum Vitamin D and the incidence of hospitalization for HF in a large prospective cohort of Italian adults.

METHODS AND RESULTS

19,092 (49% men, age range 35-99 years) HF-free individuals from the Moli-sani study, with complete data on serum Vitamin D (25-hydroxyvitamin) levels and incident hospitalized HF, were analysed. The cohort was followed up for a median of 6.2 years. Baseline serum Vitamin D levels were categorized in deficient (<10 ng/mL), insufficient (10-29 ng/mL), and normal (≥30 ng/mL) Incident cases of hospitalization for HF were identified by linkage with the regional hospital discharge registry. Hazard ratios (HRs) were calculated using Cox-proportional hazard models. The prevalence of normal, insufficient or deficient levels of Vitamin D was 12.2%, 79.6% and 8.2%, respectively. During follow-up, 562 admissions to hospital for HF were identified. The incidence of HF was 1.6%, 2.9% and 5.3%, respectively in subjects with normal, insufficient and deficient levels of Vitamin D. After multivariable analysis, individuals with deficiency of Vitamin D had a higher risk of hospitalization for HF (HR: 1.61, 95%CI: 1.06-2.43) than those with normal levels. Further adjustment for subclinical inflammation did not substantially change the association between Vitamin D deficiency and HF.

CONCLUSION

Deficiency of Vitamin D was associated, independently of known HF risk factors, with an increased risk of hospitalization for HF in an Italian adult population.

Limitations of vitamin D supplementation trials: Why observational studies will continue to help determine the role of vitamin D in health

Observational studies have shown that low vitamin D status is associated with an increased risk of a wide range of diseases. The body of observational evidence now is so large, that there have been many calls for randomized controlled trials (RCT) of vitamin D supplementation to confirm once and for all whether increasing body vitamin D levels prevents these diseases. These calls have arisen because of concern that confounding and reverse causation may explain many of the results from observational studies. However, RCTs also are prone to limitations that compromise their validity. These include low response rates that affect their external validity; and biases that affect their internal validity, such as recruitment of vitamin D sufficient people which decreases the power to detect beneficial effects, studies of long-term outcomes requiring participation for many years which decreases compliance and retention, and easy access for participants to vitamin D supplements and blood testing which increase contamination and unblinding. Because of these potential limitations, it is possible that RCTs of vitamin D supplementation may not to give a clear answer by themselves. Future decisions about the role of vitamin D in health are likely to be based on the evidence from a range of study designs including RCTs, mendelian randomization studies and other observational designs.

Vitamin D and progression of carotid intima-media thickness in HIV-positive Canadians

OBJECTIVES

Based on a growing body of evidence implicating low vitamin D status in the development of cardiovascular disease (CVD), we hypothesized that in Canadian HIV-positive adults, low 25-hydroxyvitamin D (25(OH)D) concentration would be associated with increased subclinical vascular disease progression.

METHODS

We prospectively studied the relationship between baseline 25(OH)D and subsequent progression of carotid intima-media thickness (CIMT) between 2002 and 2011, in the Canadian HIV Vascular Study using stored blood specimens.

RESULTS

Of the 128 participants, 89.1% were men, the mean age (standard deviation [SD]) was 46.5 (8.2) years, 93.8% were white, and 36.7% were current smokers. Mean (SD) annual CIMT follow-up was 5.9 (1.8) years (maximum 8.5 years), providing approximately 750 patient-years of follow-up. Mean (SD) CIMT progression was 0.027 (0.030) mm/year. Mean (SD) 25(OH)D was 95.0 (46.9) nmol/L. Only 13.3% of participants were vitamin D deficient (25(OH)D < 50 nmol/L), whereas 61.7% had a 25(OH)D exceeding the sufficiency threshold (75 nmol/L). Vitamin D quartiles were inversely associated with body mass index (BMI) (P = 0.034), total cholesterol to high-density lipoprotein (HDL) cholesterol ratio (P = 0.001) and parathyroid hormone concentration (P = 0.003), but not efavirenz exposure (P = 0.141). In linear regression analyses, baseline 25(OH)D as a continuous variable was inversely associated with CIMT progression in univariable (P < 0.001) and multivariable (P < 0.001) models.

CONCLUSIONS

Baseline 25(OH)D was associated with CIMT progression in this relatively vitamin D replete, predominately white and male, Canadian HIV-positive population. Future research needs to establish causality as this may warrant more targeted screening or supplementation.

Vitamin D status and cardiometabolic risk factors across latitudinal gradient in Iranian adults: National food and nutrition surveillance

BACKGROUND

This study aimed to evaluate the vitamin D status in an adult population across latitudinal gradient and to investigate its possible associations with certain cardiometabolic risk factors.

METHODS

A total of 1406 healthy subjects aged 19-60 years were randomly selected from six regions of Iran across latitudinal gradient from 29° N to 37.5° N. Anthropometric and biochemical assessments were performed. The combination of high body mass index (>25 kg/m²), low high-density lipoprotein cholesterol (< 40 mg/dl in males and < 50 mg/dl in females) and high triglycerides (> 150 mg/dl) was defined as cardiometabolic risk factors.

RESULTS

The mean concentration of serum 25-hydroxycalciferol (25(OH)D) was 26.8±17.7 nmol/l. There were no significant differences in the mean serum 25(OH)D levels among different latitudes. Undesirable vitamin D status (deficiency and insufficiency) was found in 90.7% of the subjects. After adjustment for age and gender, the association between weight status and serum 25(OH)D was significant ( p< 0.04, odds ratio:1.49; confidence interval: 1.01-2.19). The prevalence of cardiometabolic risk factors among the subjects with serum 25(OH)D less than 27.5 nmol/l was significantly higher than those with serum calcidiol concentrations above 27.5 nmol/l (13.3% vs. 10.0%, p = 0.033).

CONCLUSION

Undesirable vitamin D status is highly prevalent among Iranian adults of both sexes irrespective of latitude and even in sunny regions. The occurrence of cardiometabolic risk factors was significantly higher in those subjects with circulating calcidiol concentrations below 27.5 nmol/l.

Vitamin D Status, Latitude and their Associations with Some Health Parameters in Children: National Food and Nutrition Surveillance

BACKGROUND

Recent data indicate a role for vitamin D in many health aspects including anthropometric measures and blood lipid profiles. Dermal vitamin D synthesis may be influenced by latitude. However, the contribution of latitude in vitamin D status and its association with anthropometric and blood lipid measures in Iranian children have not been studied to date.

METHODS

We used data from the National Food and Nutritional Surveillance Program. In total, 667 apparently healthy children aged 5-18 years were randomly selected from six provinces of Iran with different latitudes, from 29 to 37°. Weight, height, circulating 25-hydroxycalciferol; calcidiol [25(OH)D] and blood lipids were measured.

RESULTS

In total, 16.7 and 4.1% of children were overweight or obese, respectively. The mean 25(OH)D concentration was 27.3 ± 17.6 nmol/l (95% confidence interval: 26.0-28.7 nmol/l). Over 93% of all children had suboptimal circulating calcidiol concentrations. Undesirable status of vitamin D, serum triglyceride and low-density lipoprotein were all more prevalent in children living in regions  >33° latitude than those in  <33°, significantly. There was no significant difference in duration of sun exposure between children living in latitudes below and above 33° (p = 0.093). In multivariate regression model, sex, latitude, body mass index for age z-score and sun exposure duration were independently related to 25(OH)D concentrations, but age was not.

CONCLUSION

Despite significant association of latitude and vitamin D status, hypovitaminosis D is prevalent across latitude gradient in Iranian children. Our findings warrant immediate sustainable nutritional intervention, including supplementation, to protect children from hypovitaminosis D irrespective of the latitude of their residence.

The Vitamin D Assessment (ViDA) Study: design of a randomized controlled trial of vitamin D supplementation for the prevention of cardiovascular disease, acute respiratory infection, falls and non-vertebral fractures

Observational studies have shown that low vitamin D status is associated with an increased risk of cardiovascular disease, acute respiratory infection, falls and non-vertebral fractures. We recruited 5110 Auckland adults, aged 50-84 years, into a randomized, double-blind, placebo-controlled trial to test whether vitamin D supplementation protects against these four major outcomes. The intervention is a monthly cholecalciferol dose of 100,000IU (2.5mg) for an estimated median 3.3 years (range 2.5-4.2) during 2011-2015. Participants were recruited primarily from family practices, plus community groups with a high proportion of Maori, Pacific, or South Asian individuals. The baseline evaluation included medical history, lifestyle, physical measurements (e.g. blood pressure, arterial waveform, lung function, muscle function), and a blood sample (stored at -80°C for later testing). Capsules are being mailed to home addresses with a questionnaire to collect data on non-hospitalized outcomes and to monitor adherence and potential adverse effects. Other data sources include New Zealand Ministry of Health data on mortality, hospitalization, cancer registrations and dispensed pharmaceuticals. A random sample of 438 participants returned for annual collection of blood samples to monitor adherence and safety (hypercalcemia), including repeat physical measurements at 12 months follow-up. The trial will allow testing of a priori hypotheses on several other endpoints including: weight, blood pressure, arterial waveform parameters, heart rate variability, lung function, muscle strength, gait and balance, mood, psoriasis, bone density, and chronic pain.

The Role of Vitamin D in the Aging Adult

The number of individuals aged 65 and older is expected to more than double from 2012 to 2060. The role of vitamin D in the prevention and treatment of diseases associated with aging has not been well studied. Traditionally, the role of vitamin D focused on the maintenance of skeletal health in the older adult. With the discovery of vitamin D receptors in the nervous, cardiovascular and endocrine systems, the role of vitamin D and its impact on these systems has become an important area of research. Older adults are at risk for lower levels of vitamin D as a result of decreased cutaneous synthesis and dietary intake of vitamin D. Epidemiologic evidence indicates an association between low levels of vitamin D and diseases associated with aging such as cognitive decline, depression, osteoporosis, cardiovascular disease, hypertension, type 2 diabetes, and cancer. Clinical trials to determine the benefit of vitamin D supplementation in preventing and treating such diseases are in progress. This paper highlights current evidence regarding the role that vitamin D may play in diseases associated with aging and addresses the need for well-designed randomized trials to examine its benefit on health outcomes in the older adult.

Dietary intake and adherence to the 2010 Dietary Guidelines for Americans among individuals with chronic spinal cord injury: a pilot study

OBJECTIVE

To investigate dietary intake and adherence to the 2010 Dietary Guidelines for Americans in individuals with chronic spinal cord injury (SCI) and able-bodied individuals.

DESIGN

A pilot study of dietary intake among a sample of individuals with SCI >1 year ago from a single site compared with able-bodied individuals.

PARTICIPANTS/METHODS

One hundred black or white adults aged 38-55 years old with SCI >1 year and 100 age-, sex-, and race-matched adults enrolled in the Coronary Artery Risk Development in Young Adults (CARDIA) study. Dietary intake was assessed by the CARDIA dietary history. Linear regression analysis was used to compare dietary intake between the subjects with SCI and those enrolled in the CARDIA study. Further, adherence to the 2010 Dietary Guidelines for dairy, fruits, and vegetables, and whole-grain foods was assessed.

RESULTS

Compared with CARDIA participants, participants with SCI consumed fewer daily servings of dairy (2.10 vs. 5.0, P < 0.001), fruit (2.01 vs. 3.64, P = 0.002), and whole grain foods (1.20 vs. 2.44 P = 0.007). For each food group, fewer participants with SCI met the recommended servings compared with the CARDIA participants. Specifically, the participants with SCI and in CARDIA who met the guidelines were, respectively: dairy, 22% vs. 54% (P < 0.001), fruits and vegetables 39% vs. 70% (P = 0.001), and whole-grain foods 8% vs. 69.6% (P = 0.001).

CONCLUSIONS

Compared with able-bodied individuals, SCI participants consumed fewer daily servings of fruit, dairy, and whole grain foods than proposed by the 2010 Dietary Guideline recommendations. Nutrition education for this population may be warranted.

25-Hydroxyvitamin D and ankle-brachial blood pressure index in adults without peripheral artery disease

BACKGROUND

Inverse association between lower level of 25-hydroxyvitamin D [25(OH)D] and higher prevalence of peripheral arterial disease (PAD) among individuals with cardiovascular diseases (CVD) is known. Less is known about the relationship between 25(OH)D and ankle-brachial blood pressure index (ABPI) in asymptomatic adults. We hypothesized a nonlinear relationship between 25(OH)D and ABPI in asymptomatic adults without PAD.

METHODS

Data from the continuous NHANES (2001-2004) was used. Minimum of the two reported ABPI value was chosen for each individual (>18 years). Linear regression models with spline adjusted for demographic and traditional risk factors for CVD were used to examine nonlinear relationship between 25(OH)D and ABPI. Mean changes in ABPI per 10 ng/mL change in 25(OH)D were reported.

RESULTS

Mean (SD) age and 25(OH)D levels of 4979 participants (48% females) were 60.4 (13.22) years and 22.1 (8.68) ng/mL, respectively, while mean (SD) ABPI was 1.07 (0.15). We observed positive association between 25(OH)D and ABPI both in the univariable and multivariable regression models (all p < 0.05). In univariable regression with spline, a significant increase in ABPI (ß = 0.03, 95% CI: 0.02-0.04) was observed until 25(OH)D reached but not above 27 ng/mL. Similarly, in multivariable spline models, 25(OH)D was positively associated with ABPI (ß = 0.02, 95% CI: 0.01-0.03) only up to 27 ng/mL.

CONCLUSIONS

In asymptomatic adults without PAD, rising serum 25(OH)D concentration but not above 27 ng/mL was associated with statistically significant increase in ABPI.

Investigating the association of vitamin D seasonality on inflammatory and hemostatic markers

Seasonal variations in health outcomes are commonly used to hypothesize a link with nutritional vitamin D (25-hydroxyvitamin D, 25(OH)D) status. The majority of vitamin D intake is from skin exposure to sunlight and varies seasonally in countries at a distance away from the Equator. However, despite the strong seasonality of vitamin D intake, no statistical method using cyclical patterns has been proposed to deduce an association between 25(OH)D and health indicators. Our motivation was to overcome the influence of related confounders, such as obesity, between 25(OH)D and health indicators: obesity would be expected to have little or no effect on the seasonal variations in 25(OH)D and in five inflammatory/hemostatic health outcomes (fibrinogen, tissue plasminogen activator [tPA], von Willebrand factor [vWF], C-reactive protein [CRP], and D-dimer). The data analyzed was from the 1958 British birth cohort biomedical survey (n = 6195) and the biomarkers were ascertained from blood drawn over an 18-mo period. We used mediation analysis to determine whether the seasonal variations of the outcomes were mediated by 25(OH)D to infer an association. The assumptions of mediation analysis fit naturally into the study's cross-sectional setting, where day of year of blood collection is the independent variable transformed by the harmonic function, and 25(OH)D is the mediator of the seasonal variation of the outcomes. The harmonic terms were tested to establish the presence of seasonal variation in the outcomes and 25(OH)D in order to determine whether the statistical mediation test could be applied. The data were collected over an 18-mo period and assayed in multiple batches to measure the serum biomarkers. When the assay batches were modeled as fixed effects, significant correlation was found with date of when blood was drawn. Thus, variation in assay batches was accounted for as random effects terms on the intercept in linear mixed-effects models. Inferences were based on tests from mediation analysis defined by the product of regression coefficients; we extended this test to allow for harmonic functions with multiple frequencies in order to statistically test the mediated effect through 25(OH)D. This was done using parametric bootstrap when the models were run in the Frequentist setting. We also replicated the analyses in the Bayesian setting to ascertain the change in amplitude of the seasonal variation that was due to 25(OH)D. Out of the five health outcomes, three (tPA, D-dimer, and fibrinogen) had significant seasonal associations that were partially mediated through 25(OH)D, one (vWF) had a seasonal pattern not mediated through 25(OH)D, and finally another (CRP) had no significant seasonal pattern. The association of 25(OH)D was strongest for tPA, and less so for D-dimer and fibrinogen. Our results and adaption of the mediation test show that there is broad potential in using seasonal variations of health indicators to deduce an association that may have not been affected by nonseasonal confounding.

Vitamin D and risk of future hypertension: meta-analysis of 283,537 participants

The evidence on the association between baseline vitamin D status and risk of incident hypertension in general populations is limited and has not been reliably quantified. We conducted a systematic review and meta-analysis of published prospective studies evaluating the associations of baseline vitamin D status (circulating 25-hydroxyvitamin D [25(OH)D] levels and dietary vitamin D intake) with risk of hypertension. Eligible studies were identified in a literature search of MEDLINE, EMBASE, and Web of Science up to November 2012. Pooled relative risks (RRs) with 95% confidence intervals were calculated using random effects models. Generalized least-squares trend estimation was used to assess dose-response relationships. Of the 2,432 articles reviewed for eligibility, eight unique prospective cohorts with aggregate data on 283,537 non-overlapping participants and 55,816 incident hypertension cases were included. The RRs (95% CIs) for hypertension in a comparison of extreme thirds of baseline levels of vitamin D were 0.70 (0.58, 0.86) for seven studies that measured blood 25(OH) D levels and 1.00 (0.95, 1.05) for four studies that assessed dietary vitamin D intake. The pooled RR of incident hypertension per 10 ng/mL increment in baseline 25(OH)D levels was 0.88 (0.81, 0.97) in dose-response analysis. Evidence was lacking of heterogeneity among studies that measured blood 25(OH) D levels and those that assessed dietary vitamin D status. Studies are needed to determine whether the association of vitamin D with hypertension represents a causal association and also to determine whether vitamin D therapy may be beneficial in the prevention or the treatment of hypertension.

Vitamin D levels do not predict cardiovascular events in statin-treated patients with stable coronary disease

BACKGROUND

This post hoc nested case-control analysis of the TNT study was designed to investigate whether baseline vitamin D level is a significant predictor of cardiovascular risk among statin-treated patients and whether changes in vitamin D after treatment with atorvastatin are associated with improved cardiovascular outcomes.

METHODS

A total of 10,001 patients with stable coronary heart disease were randomized to atorvastatin 80 or 10 mg for a median of 4.9 years. This analysis included 1,509 patients (497 with a subsequent cardiovascular event and 1,012 without an event) with vitamin D levels determined at baseline and 1 year. Event rates were analyzed by Cox proportional hazard model by baseline vitamin D levels, with vitamin D as a continuous variable, and with change in vitamin D level as the predictor.

RESULTS

Vitamin D deficiency (<15 ng/mL) or insufficiency (15- <30 ng/mL) was present in 108 (7.2%) of 1,509 and 625 (41.4%) of 1,509 of patients, whereas 46 (3.0%) of 1,509 had elevated vitamin D. There was no relationship between baseline vitamin D levels or change in vitamin D levels and cardiovascular events or mortality. Modeling of events with vitamin D as a continuous variable similarly showed no relationship of vitamin D to events. These findings held true after adjustment for seasonal variations in vitamin D and other confounders.

CONCLUSION

In statin-treated patients with stable coronary heart disease, vitamin D levels did not predict cardiovascular risk. Changes in plasma concentrations of vitamin D after 1 year of treatment made no contribution to the efficacy of atorvastatin therapy.

The association between vitamin D levels and recurrent group A streptococcal tonsillopharyngitis in adults

OBJECTIVES

To determine the association between recurrent group A streptococcal (GAS) tonsillopharyngitis and serum 25-hydroxy (25(OH)) vitamin D among adult subjects.

METHODS

Adult patients with tonsillopharyngitis between January 2007 and December 2009 were reviewed and identified retrospectively. Cases with a medical history of recurrent GAS tonsillopharyngitis were compared to age- and gender-matched individuals without a medical history of GAS tonsillopharyngitis. Recurrent tonsillopharyngitis was defined as three or more episodes of GAS tonsillopharyngitis per year for a period of two consecutive years.

RESULTS

Fifty-four cases with recurrent GAS tonsillopharyngitis and 50 controls were enrolled. There were no significant differences between cases and controls with regard to mean age (41 ± 13 vs. 42 ± 12 years; p=0.7) and male gender (55% vs. 54%; p=0.6). Mean serum levels of 25(OH) vitamin D among subjects with recurrent GAS tonsillopharyngitis were significantly lower from the controls (11.5 ng/ml ± 4.7 vs. 26 ng/ml ± 7; p=0.001). Multiple regression analysis showed that a serum 25(OH) vitamin D level <20 ng/ml was associated with recurrent GAS tonsillopharyngitis (odds ratio 1.62, 95% confidence interval 1.51-1.76; p < 0.001).

CONCLUSIONS

Our findings indicate a link between vitamin D deficiency and the recurrence of GAS tonsillopharyngitis.

Vitamin D deficiency-induced hypertension is associated with vascular oxidative stress and altered heart gene expression

Vitamin D deficiency (VDD) is associated with an increased cardiovascular risk. We investigated the effect of VDD on the cardiovascular system of growing male rats fed with a vitamin D-deficient diet. Using isolated rat aorta, we assessed both superoxide anion and endothelial-dependent relaxations. Microarray technology was used to identify changes induced by VDD in cardiac gene expression. Compared with control, VDD increased systolic blood pressure (P < 0.05) and superoxide anion production in the aortic wall (P < 0.05) and tended to increase serum levels of angiotensin II and atrial natriuretic peptide (P < 0.15). However, VDD slightly improved maximal relaxation to acetylcholine from 75 % ± 3% to 83% ± 2% (P < 0.05). Incubation of aortic rings either with nitro-l-arginine methyl ester (l-NAME) or catalase did not eliminate the enhancement of endothelial-mediated relaxation observed in vitamin D-deficient rats. Only incubation with indometacin or calcium-activated potassium channels blockers suppressed this difference. Compared with control, the expression of 51 genes showed different expression, including several genes involved in the regulation of oxidative stress and myocardial hypertrophy. In conclusion, VDD in early life increases arterial blood pressure, promotes vascular oxidative stress, and induces changes in cardiac gene expression. However, the endothelial-mediated regulation of vasomotor tone is maintained throughout the enhancement of an NO-independent compensatory pathway.

Associations of 25-hydroxyvitamin D2 and D3 with cardiovascular risk factors in childhood: cross-sectional findings from the Avon Longitudinal Study of Parents and Children

CONTEXT

Studies in adults have reported associations of low circulating total 25-hydroxyvitamin D with increased cardiovascular disease and risk factors. Evidence of associations in children, however, is limited, and it is unknown whether associations with risk factors differ for each 25-hydroxyvitamin D analog [25-hydroxyvitamin D(2) (25[OH]D(2)) and 25-hydroxyvitamin D(2) (25[OH]D(3))].

OBJECTIVE

The objective of the study was to compare associations of 25(OH)D(2) and 25(OH)D(3) with cardiovascular risk factors in children.

DESIGN/SETTING

The design of the study was a cross-sectional study of 4274 children (mean age 9.9 yr) from the Avon Longitudinal Study of Parents and Children.

MAIN OUTCOMES

The main outcomes included blood pressure, lipids [triglycerides, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol (HDL-C)], apolipoproteins (Apo-A1 and Apo-B), adiponectin, leptin, C-reactive protein, and IL-6.

RESULTS

In confounder-adjusted models, 25(OH)D(2) was inversely associated with Apo-A1 (change per doubling of exposure: -0.74 mg/dl; 95% confidence interval -0.14, -0.04) and triglycerides (relative percentage change per doubling of exposure: -1.64%; -3.27, 0.01) and positively associated with C-reactive protein (8.42%; 3.40, 13.58) and IL-6 (5.75%; 1.83, 9.25). 25(OH)D(3) was positively associated with HDL-C (0.04 mmol/liter; 0.02, 0.06), Apo-A1 (1.96 mg/dl; 0.65, 3.24), and adiponectin (0.47 μg/ml; 0.15, 0.79). There was statistical evidence that associations of 25(OH)D(2) and 25(OH)D(3) with HDL-C, Apo-A1, and IL-6 differed from each other (all P values for differences ≤0.02).

CONCLUSIONS

Higher circulating 25(OH)D(3) was associated with cardioprotective levels of HDL-C, Apo-A1, and adiponectin in children. Associations of 25(OH)D(2) with cardiovascular risk factors were in mixed directions. It is necessary to see whether these associations are replicated in large prospective studies.

Vitamin composition of ethnic foods commonly consumed in Europe

BACKGROUND

Vitamin analyses are particularly important for estimating dietary intakes, determining nutritional status and regulating food labelling. Due to the increased popularity of ethnic foods, the vitamin composition of these foods is required to ensure that national food databases are up-to-date.

OBJECTIVES

The key objective of this study was to generate new and reliable data on the contents of fat-soluble vitamins, including vitamins A (all trans-retinol), D(3) & E (α-tocopherol) and those that are water-soluble (vitamins B(6), B(12), C, biotin, folate, niacin, pantothenic acid, riboflavin, and thiamin) in ethnic foods commonly consumed in Europe.

DESIGN

Thirty commonly-consumed ethnic foods in Europe (from Belgium, France, Israel, Italy, The Netherlands, and the UK) were analysed using harmonised methodologies for identification of representative foods, sampling, data scrutiny and documentation to generate reliable data. Analyses were carried out using International standard methods.

RESULTS

CERTAIN VITAMINS WERE PRESENT IN APPRECIABLE AMOUNTS: β-carotene in tayer leaves (7919µg/100g), thiamin in frik dry (0.24mg/100g), riboflavin in mbinzo worms (0.79mg/100g,) and niacin in commercial soy patty (17.5mg/100g). However, retinol, pantothenic acid, vitamins D and B(12) were below detectable levels in the majority of the foods analysed.

CONCLUSIONS

The majority of the foods contained most of the water-soluble vitamins but lacked fat-soluble vitamins. However, these preliminary data represent only a small number of foods per country and so no conclusions about vitamin imbalances can be drawn. Additional data are required on a much wider range of commonly-consumed ethnic foods to make firm conclusions about adequacy of diets.

Heart failure is a clinically and densitometrically independent risk factor for osteoporotic fractures: population-based cohort study of 45,509 subjects

OBJECTIVE

The aim of the study was to determine whether heart failure is associated with an increased risk of major osteoporotic fractures that is independent of bone mineral density (BMD).

METHODS

We conducted a population-based cohort study in Manitoba, Canada, by linking a clinical registry of all adults 50 yr of age and older who underwent initial BMD testing from 1998-2009 with administrative databases. We collected osteoporosis risk factors, comorbidities, medications, and BMD results. Validated algorithms identified recent-onset heart failure before the BMD test and new fractures after. The main outcome was time to major osteoporotic fractures (i.e. clinical vertebrae, distal forearm, humerus, and hip), and multivariable proportional hazards models were used for analyses.

RESULTS

The cohort consisted of 45,509 adults; 1,841 (4%) had recent-onset heart failure. Subjects with heart failure were significantly (P < 0.001) older (74 vs. 66 yr) and had more previous fractures (21 vs. 13%) and lower total hip BMD [T-score, -1.3 (sd 1.3) vs. -0.9 (sd 1.2)] than those without. There were 2703 incident fractures over the 5-yr observation. Overall, 10% of heart failure subjects had incident major fractures compared with 5% of those without [unadjusted hazard ratio (HR), 2.45; 95% confidence interval (CI), 2.11-2.85]. Adjustment for osteoporosis risk factors, comorbidities, and medications attenuated but did not eliminate this association (HR, 1.33; 95% CI, 1.11-1.60), nor did further adjustment for total hip BMD (HR, 1.28; 95% CI, 1.06-1.53).

CONCLUSIONS

Heart failure is associated with a 30% increase in major fractures that is independent of traditional risk factors and BMD, and it also identifies a high-risk population that may benefit from increased screening and treatment for osteoporosis.

Vitamin D deficiency is a predictor of reduced survival in patients with heart failure; vitamin D supplementation improves outcome

AIMS

Vitamin D deficiency is a highly prevalent, global phenomenon. The prevalence in heart failure (HF) patients and its effect on outcome are less clear. We evaluated vitamin D levels and vitamin D supplementation in patients with HF and its effect on mortality.

METHODS AND RESULTS

25-Hydroxyvitamin D [25(OH)D] levels were evaluated in HF patients from a health maintenance organization (HMO), and compared them with those of the rest of the members of the HMO. Patients with HF (n = 3009) had a lower median 25(OH)D level compared with the control group (n = 46 825): 36.9 nmol/L (interquartile range 23.2-55.9) vs. 40.7 nmol/L (26.7-56.9), respectively, P < 0.00001. The percentage of patients with vitamin D deficiency [25(OH)D <25 nmol/L] was higher in patients with HF compared with the control group (28% vs. 22%, P < 0.00001). Only 8.8% of the HF patients had optimal 25(OH)D levels (≥75 nmol/L). Median clinical follow-up was 518 days. Cox regression analysis demonstrated that vitamin D deficiency was an independent predictor of increased mortality in patients with HF [hazard ratio (HR) 1.52, 95% confidence interval (CI) 1.21-1.92, P < 0.001] and in the control group (HR 1.91, 95% CI 1.48-2.46, P < 0.00001). Vitamin D supplementation was independently associated with reduced mortality in HF patients (HR 0.68, 95% CI 0.54-0.85, P < 0.0001). Parameters associated with vitamin D deficiency in HF patients were decreased previous solar radiation exposure, body mass index, diabetes, female gender, pulse, and decreased calcium and haemoglobin levels.

CONCLUSIONS

Vitamin D deficiency is highly prevalent in HF patients and is a significant predictor of reduced survival. Vitamin D supplementation was associated with improved outcome.

Receptor activator of nuclear factor-κB ligand is a novel inducer of myocardial inflammation

AIMS

Although increased levels of myocardial receptor activator of nuclear factor (NF)-κB ligand (RANKL) have been reported in heart failure, the role of this pathway in mediating activation of inflammatory pathways during myocardial remodelling is less well understood. This study sought to determine the role of myocardial RANKL in regulating cytokine expression.

METHODS AND RESULTS

A marked increase in RANKL expression occurred as early as 6h following transverse aortic constriction (TAC) in mouse hearts and persisted at 3 and 17 days. An increase in tumour necrosis factor-α (TNF-α), interleukin (IL)-1α, and IL-1β was observed in the hypertrophied hearts only at 3 or 17 days after TAC. Treatment with losartan significantly attenuated TAC-induced cardiac hypertrophy, in parallel with decreased expression of RANKL, TNF-α, IL-1α, and IL-1β. Furthermore, injection of a RANKL-neutralizing monoclonal antibody attenuated RANKL-induced cytokine expression. RANKL stimulated expression of TNF-α, IL-1α, and IL-1β in neonatal rat cardiomyocytes via activation of NF-κB. RANKL-induced NF-κB activation and expression of these cytokines were both attenuated when RANK, receptor for RANKL, or TRAF2 or TRAF6, adaptors for RANK, was silenced by siRNA. Furthermore, inhibitors of phospholipase C (PLC), protein kinase C (PKC), and inhibitor of κB kinase also significantly inhibited RANKL-induced cellular activities, but inhibitors of phosphatidylinositol 3-kinase, extracellular signal-regulated kinase, or p38 mitogen-activated protein kinase were without effect.

CONCLUSION

Our data demonstrate for the first time that the pressure-overloaded myocardium generates RANKL, which induces TNF-α, IL-1α, and IL-1β production via a RANK-TRAF2/TRAF6-PLC-PKC-NF-κB-mediated autocrine mechanism.

Vitamin D in chronic kidney disease

In chronic kidney disease (CKD), abnormalities in vitamin D metabolism contribute to the development of mineral and skeletal disorders, elevations in parathyroid hormone (PTH), hypertension, systemic inflammation, renal and cardiovascular damage. CKD induces a progressive loss of the capacity of the kidney not only to convert 25-hydroxyvitamin D [25(OH)D] to circulating calcitriol, the vitamin D hormone, but also to maintain serum 25(OH)D levels for non-renal calcitriol synthesis. The resulting calcitriol and 25(OH)D deficiency associates directly with accelerated disease progression and death. This chapter presents our understanding of the pathophysiology behind 25(OH)D and calcitriol deficiency in CKD, of the adequacy of current recommendations for vitamin D supplementation and PTH suppression, and of potential markers of renal and cardiovascular lesions unrelated to PTH suppression, a knowledge required for the design of trials to obtain evidence-based recommendations for vitamin D and calcitriol replacement that improve outcomes at all stages of CKD.

Parathyroid hormone, vitamin D, renal dysfunction, and cardiovascular disease: dependent or independent risk factors?

BACKGROUND

Vitamin D (Vit D) deficiency has been associated with prevalent and incident cardiovascular (CV) disease, suggesting a role for bioregulators of bone and mineral metabolism in CV health. Vitamin D deficiency leads to secondary hyperparathyroidism, and both primary and secondary hyperparathyroidism are associated with CV pathology. Parathyroid hormone (PTH) is an important regulator of calcium homeostasis, and its impact on CV disease risk is of interest. We tested whether elevated PTH is associated with CV disease and whether risk associations depend on Vit D status and renal function.

METHODS

Patients in the Intermountain Healthcare system with concurrent PTH and Vit D as 25-hydroxy-vitamin D (25[OH]D) levels were studied (N = 9,369, age 63 ± 16 years, 36% male). Parathyroid hormone levels were defined as low (<15 pg/mL), normal (15-75 pg/mL), or elevated (>75 pg/mL). Prevalence and incidence of hypertension, diabetes, hyperlipidemia, coronary artery disease/myocardial infarction, heart failure, stroke, and peripheral vascular disease were determined by the International Classification of Diseases, Ninth Revision codes documented in electronic medical records at baseline and, for incident events, during an average of 2.0 ± 1.5 years (maximum 7.5 years) of follow-up.

RESULTS

Parathyroid hormone elevation at baseline was noted in 26.1% of the study population. Highly significant differential CV prevalence/incidence rates for most CV risk factors, disease diagnoses, and mortality were noted for PTH >75 pg/mL (by 1.25- to 3-fold). Parathyroid hormone correlated only weakly (r = -0.15) with 25(OH)D and moderately with glomerular filtration rate (r = -0.36). 25(OH)D, standard risk factors, and renal dysfunction variably attenuated PTH risk associations, but risk persisted after full multivariable adjustment.

CONCLUSIONS

Elevated PTH is associated with a greater prevalence and incidence of CV risk factors and predicts a greater likelihood of prevalent and incident disease, including mortality. Risk persists when adjusted for 25(OH)D, renal function, and standard risk factors. Parathyroid hormone represents an important new CV risk factor that adds complementary and independent predictive value for CV disease and mortality.

Vitamin D deficiency prevalence and cardiovascular risk in Israel

BACKGROUND

Accumulated data in the past years suggest that vitamin D deficiency has an adverse effect on cardiovascular (CVD) health and that its prevalence is significantly higher among patients with CVD risk factors, contributing to the pathogenesis of CVD.

MATERIALS AND METHODS

This is a cross-sectional analysis of a relatively large database derived from a health care maintenance organization. The population consisted of individuals 18 years and older who had undergone blood tests for vitamin D levels for any reason during 2001-2008.

RESULTS

The study population consisted of 34,874 individuals: 26,699 (76·6%) were women at a mean ± SD age of 55 ± 15 and 8175 men (23·4%) aged 55 ± 17. The mean ± SD vitamin D level was 23·2 ± 10·1 and 22·7 ± 9·9 for men and women, respectively. The prevalence of vitamin D deficiency or insufficiency (vitamin D levels < 30 ng mL(-1)) for the entire study population was surprisingly high for men and women (79·2% and 77·5%, respectively). This remained consistent with only little variation when stratified by age. The group with vitamin D < 15 ng mL(-1) vs. the group with vitamin D levels ≥ 30 ng mL(-1) demonstrated a significant (P < 0·031) age-adjusted odds ratios for the presence of hypertension, diabetes mellitus, dyslipidemia, obesity and peripheral vascular disease for women (OR = 1·19; 1·65; 1·13; 2·28; 1·85, respectively), and the presence of all the above except hypertension in men (OR = 1·51; 1·28; 2·06; 1·73, respectively).

CONCLUSIONS

Vitamin D deficiency is associated with CVD and other risk factors in this Israeli study population. The prevalence of the deficiency in Israel is similar to the prevalence found in less sunny regions.

Relation of vitamin D deficiency to cardiovascular risk factors, disease status, and incident events in a general healthcare population

Vitamin D recently has been proposed to play an important role in a broad range of organ functions, including cardiovascular (CV) health; however, the CV evidence-base is limited. We prospectively analyzed a large electronic medical records database to determine the prevalence of vitamin D deficiency and the relation of vitamin D levels to prevalent and incident CV risk factors and diseases, including mortality. The database contained 41,504 patient records with at least one measured vitamin D level. The prevalence of vitamin D deficiency (≤30 ng/ml) was 63.6%, with only minor differences by gender or age. Vitamin D deficiency was associated with highly significant (p <0.0001) increases in the prevalence of diabetes, hypertension, hyperlipidemia, and peripheral vascular disease. Also, those without risk factors but with severe deficiency had an increased likelihood of developing diabetes, hypertension, and hyperlipidemia. The vitamin D levels were also highly associated with coronary artery disease, myocardial infarction, heart failure, and stroke (all p <0.0001), as well as with incident death, heart failure, coronary artery disease/myocardial infarction (all p <0.0001), stroke (p = 0.003), and their composite (p <0.0001). In conclusion, we have confirmed a high prevalence of vitamin D deficiency in the general healthcare population and an association between vitamin D levels and prevalent and incident CV risk factors and outcomes. These observations lend strong support to the hypothesis that vitamin D might play a primary role in CV risk factors and disease. Given the ease of vitamin D measurement and replacement, prospective studies of vitamin D supplementation to prevent and treat CV disease are urgently needed.

[Solaria, vitamin D, and skin cancer]

BACKGROUND

Some researchers have suggested to use an indoor tanning device (solarium) as a vitamin D source for disease prevention.

MATERIAL AND METHODS

The article is based on non-systematic searches in PubMed and ISI, and the authors' experience from epidemiologic research and studies of solarium irradiance.

RESULTS

Vitamin D deficiency is an established risk factor for rickets in children and osteomalacia in adults; and is associated with an increased risk of osteoporosis and fractures. Several studies have found a beneficial role of vitamin D on both incidence and prognosis for other diseases, e.g. cancer, but causal relationships with vitamin D cannot yet be concluded. Sun exposure, our main source of vitamin D, is also an established risk factor of skin cancer. Moderate sun exposure generally provides an adequate amount of vitamin D during summer. Dietary intake of vitamin D is adamant when sun exposure is low. Solarium use seems to increase. Mean irradiance from solariums is higher than that from the summer sun in Oslo; 1.5 times higher for UVB and 3.5 times for UVA . Use of solarium increases the risk of skin cancer and was classified as carcinogenic to humans in 2009; positive health effects are not sufficiently documented.

INTERPRETATION

Recommendations on restricted solarium use should be maintained.

High latitude and marine diet: vitamin D status in elderly Faroese

Human subjects obtain their vitamin D from the diet, especially from marine food, and from endogenous synthesis following cutaneous sun exposure. The risk of an insufficient vitamin D synthesis is increased in northern populations, but it may be counteracted by a high intake of marine food in fishing populations, e.g. at the Faroe Islands. We examined the vitamin D status and its statistical determinants in a cross-sectional study of 713 elderly Faroese aged 70-74 years, about two-thirds of all the eligible residents in this age group. Clinical examination included measurement of body weight and height, and marine food intake was estimated using a questionnaire. We measured serum 25-hydroxyvitamin D3 (S-25(OH)D3) by LC-MS/MS in 669 of the 713 subjects in whom sufficient serum was available. Of the population, 19% had S-25(OH)D3 concentrations < 25 nmol/l, and only 10.3% of the population had S-25(OH)D3 concentrations >80 nmol/l. In a logistic regression analysis, BMI < 30 kg/m2, blood sampling in summer season, eating pilot whale blubber more than once per month and female sex were positively associated with vitamin D levels >80 nmol/l. The high prevalence of low vitamin D levels among the elderly Faroese population reflects the low skin synthesis during most months of the year, which is caused by the limited sun exposure and insufficient benefits from marine diet. Thus, even in a population with a high intake of marine food, the northern latitude causes a low vitamin D status. Efforts to improve vitamin D status in this population are warranted.

Seasonal and age-related differences in serum 25-hydroxyvitamin D, 1,25-dihydroxyvitamin D and parathyroid hormone in patients from Western Norway

OBJECTIVE

The aim of this study was to investigate the seasonal and age-related variation of vitamin D and PTH serum concentrations in a large general patient population in Western Norway.

DESIGN

A retrospective study was conducted at the Hormone laboratory, Haukeland University Hospital, Bergen, Norway. All analyses of 25-hydroxyvitamin D (25(OH)D) (n = 8325), 1,25-dihydroxyvitamin D (1,25(OH)2D) (n = 4509) and PTH (n = 4203) requested from private practitioners from 2005 to 2008 were included. All three analytes were available in 1551 subjects. Subjects. Mean age of the study population was 49.8 years and 70.9% of the samples were from women.

RESULTS

The highest concentrations of 25(OH)D and 1,25(OH)2D were observed in July-September. In April 43% of the studied population had 25(OH)D concentrations below 50 nmol/L. There was a positive correlation between 25(OH)D and 1,25(OH)2D (p < 0.001). The levels of 25(OH)D and PTH were negatively correlated (p < 0.001) while 1,25(OH)2D and PTH showed a weak positive correlation (p = 0.015). We observed higher concentrations of 25(OH)D (p = 0.003) and lower 1,25(OH)2D levels (p < 0.001) in the older age groups. PTH increased throughout the whole age span (p < 0.001).

CONCLUSION

We observed a seasonal variation in 25(OH)D and 1,25(OH)2D with low serum concentrations during winter/early spring while PTH showed an inverse pattern. Higher levels of PTH in winter and the elderly may reflect an impaired vitamin D status that may affect calcium homeostasis and bone health.

Vitamin D and depression: where is all the sunshine?

Depression in its own right is a disabling condition impairing all aspects of human function. In persons with a chronic medical disease, depression often makes the management of chronic illness more difficult. Recently, vitamin D has been reported in the scientific and lay press as an important factor that may have significant health benefits in the prevention and the treatment of many chronic illnesses. Most individuals in this country have insufficient levels of vitamin D. This is also true for persons with depression as well as other mental disorders. Whether this is due to insufficient dietary intake, lifestyle (e.g., little outdoor exposure to sunshine), or other factors is addressed in this paper. In addition, groups at risk and suggested treatment for inadequate vitamin D levels are addressed. Effective detection and treatment of inadequate vitamin D levels in persons with depression and other mental disorders may be an easy and cost-effective therapy which could improve patients' long-term health outcomes as well as their quality of life.

Levels of vitamin D and cardiometabolic disorders: systematic review and meta-analysis

Cardiometabolic disorders and vitamin D deficiency are becoming increasingly more prevalent across multiple populations. Different studies have suggested a potential association between abnormal vitamin D levels and multiple pathological conditions including cardiovascular diseases and diabetes. We aimed to evaluate the association between vitamin D levels, using 25-hydroxy vitamin D (25OHD) as an indicator of vitamin D status, and the presence of cardiometabolic disorders including cardiovascular disease, diabetes and metabolic syndrome. We performed a systematic review of the current literature on vitamin D and cardiometabolic disorders using the PubMed and Web of Knowledge databases in September 2009. Studies in adults looking at the effect of vitamin D levels on outcomes relating to cardiometabolic disorders were selected. We performed a meta-analysis to assess the risk of developing cardiometabolic disorders comparing the highest and lowest groups of serum 25OHD. From 6130 references we identified 28 studies that met our inclusion criteria, including 99,745 participants. There was moderate variation between the studies in their grouping of 25OHD levels, design and analytical approach. We found that the highest levels of serum 25OHD were associated with a 43% reduction in cardiometabolic disorders [OR 0.57, 95% (CI 0.48-0.68)]. Similar levels were observed, irrespective of the individual cardiometabolic outcome evaluated or study design. High levels of vitamin D among middle-age and elderly populations are associated with a substantial decrease in cardiovascular disease, type 2 diabetes and metabolic syndrome. If the relationship proves to be causal, interventions targeting vitamin D deficiency in adult populations could potentially slow the current epidemics of cardiometabolic disorders.