Vitamin D and cardiovascular outcomes: a systematic review and meta-analysis

Hypertension, pulse, and other cardiovascular risk factors and vitamin D status in Finnish men

BACKGROUND

Debate exists about the relationship between hypovitaminosis D and cardiovascular (CVD) risk.

METHODS

This study investigated baseline (n=2,271) 25-hydroxyvitamin D (25(OH)D) and baseline and 4 year (n=1,957) CVD risk in a cohort of Finnish middle-aged male smokers.

RESULTS

The prevalences of measured hypertension, high pulse rate, diabetes, and coronary heart disease were 63%, 16%, 5%, and 10% at baseline and were 64%, 20%, 6%, and 16% at 4 years after baseline. The mean 25(OH)D was 41±18 nmol/L. At baseline, systolic blood pressure (β = -0.048; P = 0.02), and pulse rate (β = -0.043; P = 0.04) were both associated with lower 25(OH)D levels but not coronary heart disease or diabetes prevalence. On remeasuring CVD risk 4 years after baseline, the only significant association with baseline 25(OH)D levels was high pulse rate (β = -0.077; P = 0.001). In addition, a higher 25(OH)D level at baseline was associated with a change in pulse rate (β = -0.055; P = 0.01). These trends for hypertension (baseline) and high pulse rate (baseline and 4 years after baseline) were also seen on adjusted categorical analysis (P trend < 0.05).

CONCLUSIONS

Vitamin D deficiency at baseline was associated with hypertension in Finnish male smokers, but not after 4 years. These results are consistent with recent findings in other large cohort studies with measured blood pressure. Change in pulse rate over time continued to be significantly associated with lower 25(OH)D baseline levels; this new finding should be investigated further.

Does vitamin D modulate blood pressure?

PURPOSE OF REVIEW

Both vitamin D deficiency and hypertension are highly prevalent. It is unclear whether vitamin D modulates blood pressure and therefore whether vitamin D testing and therapy should become part of routine hypertension prevention and management. This article provides an overview of the data, with special emphasis on the work published in the last 2 years.

RECENT FINDINGS

Several animal studies corroborate the strong effect of vitamin D on the renin-angiotensin-aldosterone axis. Small and large observational studies have found associations between vitamin D, increased blood pressure, and the risk of developing hypertension. In contrast, recent data from randomized trials are mixed. Two randomized trials with approximately 1 year of follow-up detected no association between vitamin D treatment and blood pressure, whereas another study of active vitamin D reported a 9-mmHg decrease in systolic blood pressure. Meta-analyses have linked vitamin D levels with blood pressure, but the effect of vitamin D administration on blood pressure remains controversial.

SUMMARY

Vitamin D deficiency is asociated with high blood pressure in observational studies. This effect is thought to be partly mediated through regulation of the renin-angiotensin-aldosterone axis. However, randomized clinical trials and their meta-analyses have yielded inconclusive results. Large randomized trials focusing on patients with severe vitamin D deficiency and hypertension are needed before vitamin D can be recommended for the prevention or treatment of hypertension.

Vitamin D and subsequent all-age and premature mortality: a systematic review

Background

All-cause mortality in the population < 65 years is 30% higher in Glasgow than in equally deprived Liverpool and Manchester. We investigated a hypothesis that low vitamin D in this population may be associated with premature mortality via a systematic review and meta-analysis.

Methods

Medline, EMBASE, Web of Science, the Cochrane Library and grey literature sources were searched until February 2012 for relevant studies. Summary statistics were combined in an age-stratified meta-analysis.

Results

Nine studies were included in the meta-analysis, representing 24,297 participants, 5,324 of whom died during follow-up. The pooled hazard ratio for low compared to high vitamin D demonstrated a significant inverse association (HR 1.19, 95% CI 1.12-1.27) between vitamin D levels and all-cause mortality after adjustment for available confounders. In an age-stratified meta-analysis, the hazard ratio for older participants was 1.25 (95% CI 1.14-1.36) and for younger participants 1.12 (95% CI 1.01-1.24).

Conclusions

Low vitamin D status is inversely associated with all-cause mortality but the risk is higher amongst older individuals and the relationship is prone to residual confounding. Further studies investigating the association between vitamin D deficiency and all-cause mortality in younger adults with adjustment for all important confounders (or using randomised trials of supplementation) are required to clarify this relationship.

Extraskeletal effects and manifestations of Vitamin D deficiency

The actions of vitamin D are not confined to bone. Vitamin D receptors are present in nearly all the nuclei and its actions are manifold. Populations deficient in vitamin D are at higher risk of developing autoimmune diseases, diabetes, cancer, infections, allergies and other chronic illnesses.

[Knowledge and prevention management of vitamin D deficiency in primary care]

OBJECTIVES

To determine the knowledge and management of vitamin D (Vit D) in primary care (PC).

DESIGN

Observational study.

LOCATION

A total of 69 primary care centres, with 57 in Barcelona and 12 in Huesca.

PARTICIPANTS

All medical and nursing graduates of these centres.

MAIN MEASUREMENTS

A specifically designed questionnaire was used to collect knowledge on the actions of Vit D (on bone metabolism, cardiovascular and immune systems), its deficiency and prevention measures.

RESULTS

Of the total of 2100 professionals, 785 completed the survey (37.78%), of whom 79.9% were women. Their mean age was 47 years (SD: 9.7). Only 4.8% knew the overall actions of Vitamin D, although the majority (66%) knew only its effects on bone metabolism. Almost two-thirds (62.4%) were unaware that its deficiency was a common problem, and 54.9% believed that photoprotection was contraindicated. Almost three-quarters of those surveyed (73.6%) never or almost never determined Vit D levels in their patients. A minority (23%) offered advice to maintain an adequate level of Vit D, with the most frequent being sun exposure (16.8%). Pediatricians were more knowledgeable (p<.001) and offered more advice for maintaining adequate levels of Vit D in blood (p<.001).

CONCLUSIONS

Most of the professionals were unaware of the overall actions of Vit D, or that its deficiency was common, or the factors contributing to this. The advice that was more often offered to avoid its deficiency was not the safest. Paediatricians are more aware of how to prevent Vit D deficiency.

Vitamin D and cardiovascular disease: is the evidence solid?

Vitamin D deficiency, prevalent in 30-50% of adults in developed countries, is largely due to inadequate cutaneous production that results from decreased exposure to sunlight, and to a lesser degree from low dietary intake of vitamin D. Serum levels of 25-hydroxyvitamin D (25-OH D) <20 ng/mL indicate vitamin D deficiency and levels >30 ng/mL are considered optimal. While the endocrine functions of vitamin D related to bone metabolism and mineral ion homoeostasis have been extensively studied, robust epidemiological evidence also suggests a close association between vitamin D deficiency and cardiovascular morbidity and mortality. Experimental studies have demonstrated novel actions of vitamin D metabolites on cardiomyocytes, and endothelial and vascular smooth muscle cells. Low 25-OH D levels are associated with left ventricular hypertrophy, vascular dysfunction, and renin-angiotensin system activation. Despite a large body of experimental, cross-sectional, and prospective evidence implicating vitamin D deficiency in the pathogenesis of cardiovascular disease, a causal relationship remains to be established. Moreover, the cardiovascular benefits of normalizing 25-OH D levels in those without renal disease or hyperparathyroidism have not been established, and questions of an epiphenomenon where vitamin D status merely reflects a classic risk burden have been raised. Randomized trials of vitamin D replacement employing cardiovascular endpoints will provide much needed evidence for determining its role in cardiovascular protection.

Plasma vitamin D and biomarkers of cardiometabolic disease risk in adult Canadians, 2007-2009

Introduction

Vitamin D may modulate cardiometabolic disease risk, although the relationship has not been investigated in the general Canadian population. Understanding this relationship may inform public health strategies to curb the incidence of cardiometabolic disease in Canada and elsewhere. The objectives of this study were to examine the association between vitamin D and traditional and novel biomarkers of cardiometabolic disease and to describe the extent of the month-to-month fluctuations of vitamin D in the Canadian population.

Methods

We examined the association between plasma 25-hydroxyvitamin D and a range of cardiometabolic risk biomarkers in participants (n = 1,928; age range, 16–79 years) from the Canadian Health Measures Survey. We conducted linear regressions analyses (adjusted for sex, waist circumference, physical activity, hormone use, and season) to assess the relationship between 25-hydroxyvitamin D and biomarkers of dysglycemia, dyslipidemia, and inflammation in the study population. We repeated analyses stratified by sex, and we evaluated monthly fluctuations in 25-hydroxyvitamin D in men and women.

Results

We observed wide month-to-month variations in 25-hydroxyvitamin D; fluctuations were more pronounced in men. Plasma 25-hydroxyvitamin D was inversely associated with insulin, insulin resistance, triglycerides, total cholesterol, low-density lipoprotein cholesterol, and the ratio of total to high-density lipoprotein cholesterol but not with fasting glucose, apolipoprotein A1, apolipoprotein B, C-reactive protein, fibrinogen, or homocysteine. This pattern varied between men and women.

Conclusion

Vitamin D may modulate various metabolic processes and may influence cardiometabolic disease risk in Canadians. These findings may have public health implications when recommending vitamin D for the prevention of cardiometabolic disease and related conditions.

Serum vitamin D and parathyroid hormone in relation to cardiac structure and function: the ICELAND-MI substudy of AGES-Reykjavik

CONTEXT

Emerging evidence suggests that vitamin D and PTH may play a role in the development of cardiac diseases.

OBJECTIVE

We investigated whether 25-hydroxyvitamin D (25OHD) and PTH concentrations are cross-sectionally associated with cardiac structure and function using magnetic resonance imaging (MRI).

DESIGN, SETTING, AND PARTICIPANTS

ICELAND-MI is a substudy of the Age, Gene/Environment Susceptibility-Reykjavik Study, an older-aged community-dwelling cohort with oversampling of participants with diabetes (29%) and measurements between 2004 and 2007. Serum 25OHD concentrations were measured using an immunoassay (n = 992). Intact PTH concentrations were measured using a 2-site immunoassay (n = 203). We included 969 participants for this cross-sectional analysis (mean age 76 ± 5.3 years, 51% female). Mean 25OHD was 54.2 ± 25.5 nmol/L and the median PTH was 4.5 pmol/L (range 1.5-18).

MAIN OUTCOMES

MRI to measure cardiac structure and function was the main outcome.

RESULTS

The lowest 25OHD category (<25 nmol/L) compared with the highest category (≥75 nmol/L) was associated with a smaller left and right atrial area in unadjusted analyses; however, the associations became nonsignificant after adjustment for covariates. The highest PTH quartile compared with the lowest quartile was significantly associated with a 7.3 g (95% confidence interval 0.8, 13.8) greater left ventricular (LV) mass and a 5.1% (-9.1, -1.1) lower LV ejection fraction compared with the lowest PTH quartile in the fully adjusted model.

CONCLUSIONS

Serum 25OHD concentrations were not associated with MRI measures in an older white population. Higher PTH concentrations were associated with greater LV mass and lower systolic function and may point to a potential role for PTH as a determinant of cardiac remodeling.

Vitamin D status and incident cardiovascular disease and all-cause mortality: a general population study

Low vitamin D status has been associated with cardiovascular disease (CVD) and mortality primarily in selected groups, smaller studies, or with self-reported vitamin D intake. We investigated the association of serum vitamin D status with the incidence of a registry-based diagnosis of ischemic heart disease (IHD), stroke, and all-cause mortality in a large sample of the general population. A total of 9,146 individuals from the two population-based studies, Monica10 and Inter99, were included. Measurements of serum 25-hydroxyvitamin D at baseline were carried out using the IDS ISYS immunoassay system in Monica10 and High-performance liquid chromatography in Inter99. Information on CVDs and causes of death was obtained from Danish registries until 31 December 2008. There were 478 cases of IHD, 316 cases of stroke, and 633 deaths during follow-up (mean follow-up 10 years). Cox regression analyses with age as underlying time axis showed a significant association between vitamin D status and all-cause mortality with a HR = 0.95 (P = 0.005) per 10 nmol/l higher vitamin D level. We found no association between vitamin D status and incidence of IHD or stroke (HR = 1.01, P = 0.442 and HR = 1.00, P = 0.920, respectively). In this large general population study, the observed inverse association between serum vitamin D status and all-cause mortality was not explained by a similar inverse association with IHD or stroke.

The relationship between vitamin D and PTH levels and cardiovascular risk in the elderly hypertensives

INTRODUCTION AND OBJECTIVE

In this study, we aimed to investigate the relationship between vitamin D, parathyroid hormone (PTH) and cardiovascular risk (CVR) in hypertensive patients aged 65 years and over.

PATIENTS AND METHODS

This study was performed with 84 hypertensive patients and 68 normotensive control group in Afyon Kocatepe University Faculty of Medicine Hospital. The determined cardiovascular risk degrees and the stages of blood pressure were compared with the levels of 25-(OH) vitamin D and PTH.

RESULTS

Mean systolic and diastolic blood pressure (BP) levels of the patients with vitamin D deficiency (VDD) were significantly higher than those without VDD (p<0.001 for both). Mean systolic and diastolic BP levels of the patients with hyperparathyroidism were significantly higher than those without hyperparathyroidism (p=0.012, p=0.036, respectively). CVR was reversely correlated with vitamin D but the correlation with hyperparathyroidism did not reach statistically significant level (r=-0.752, p<0.001) and (r=0.210, p=0.055), respectively.

CONCLUSION

These results indicate that the presence of hypertension is associated with VDD, as well as the stage of hypertension contributes to insufficiency, hyperparathyroidism and increased CVR. Clinicians should be aware and perhaps more aggressive for the treatment of HT and VDD in patients over 65 years of age.

Low serum vitamin D is not associated with an increase in mortality in oldest old subjects: the Octabaix three-year follow-up study

BACKGROUND

Poor vitamin D status, i.e. low serum levels of 25-hydroxyvitamin D [25(OH)D], is common in the general population. Prospective epidemiologic data on the association between vitamin D and mortality in oldest old subjects are limited.

OBJECTIVE

This study aimed to determine whether 25(OH)D concentrations were prospectively and independently associated with cardiovascular disease (CVD) mortality and all-cause mortality in oldest old subjects.

METHODS

A total of 312 subjects aged 85 years old at baseline (Octabaix study) were followed for 3 years. Sociodemographic and overall geriatric assessment data were collected. Serum 25(OH)D concentrations were used to assess vitamin D status. Data on overall and cardiovascular mortality were collected.

RESULTS

The mean serum 25(OH)D levels were 28 ± 30 ng/ml. During the follow-up period, 58 subjects (18.5%) died. Twenty-five of the deaths (8%) were related to CVD. There were no differences in mortality rates according to the different quartiles of vitamin D (p = 0.41 for total mortality and p = 0.86 for CVD mortality).

CONCLUSION

In community-dwelling oldest old subjects, serum 25(OH)D levels were not associated with overall or CVD mortality after a 3-year follow-up.

Study protocol: the effect of vitamin D supplements on cardiometabolic risk factors among urban premenopausal women in a tropical country -- a randomized controlled trial

BACKGROUND

Besides its classical role in musculoskeletal diseases, vitamin D deficiency has recently been found to be associated with cardiometabolic risks such as hypertension, diabetes mellitus and hypercholesterolemia. Although Malaysia is a sunshine-abundant country, recent studies found that vitamin D deficiency prevalence was significantly high. However, few published studies that measured its effect on cardiometabolic risk factors were found in Malaysia. There are also limited clinical trials carried out globally that tried to establish the causality of vitamin D and cardiometabolic risks. Therefore, a double blind, parallel, randomized controlled trial on vitamin D and cardiometabolic risks is planned to be carried out.The objective of this study is to investigate whether vitamin D supplements can reduce the cardiometabolic risk and improve the quality of life in urban premenopausal women with vitamin D deficiency.

METHODS/DESIGN

Three hundred and twenty premenopausal women working in a public university in Kuala Lumpur, Malaysia will be randomized to receive either vitamin D supplement (50,000 IU weekly for 8 weeks and 50,000 IU monthly for 10 months) or placebo for 12 months. At baseline, all participants are vitamin D deficient (≤ 20 ng/ml or 50 nmol/l). Both participants and researchers will be blinded. The serum vitamin D levels of all participants collected at various time points will only be analysed at the end of the trial. Outcome measures such as 25(OH) D3, HOMA-IR, blood pressure, full lipid profiles will be taken at baseline, 6 months and 12 months. Health related quality of life will be measured at baseline and 12 months. The placebo group will be given delayed treatment for six months after the trial.

DISCUSSION

This trial will be the first study investigating the effect of vitamin D supplements on both the cardiometabolic risk and quality of life among urban premenopausal women in Malaysia. Our findings will contribute to the growing body of knowledge in the role of vitamin D supplements in the primary prevention for cardiometabolic disease.

TRIAL REGISTRATION

ACTRN12612000452897.

Decreased serum concentrations of 25-hydroxycholecalciferol are associated with increased risk of progression to impaired fasting glucose and diabetes

OBJECTIVE

To study the association between vitamin D status and the risk of incident impaired fasting glucose (IFG) and diabetes in a population-based cohort of diabetes-free subjects.

RESEARCH DESIGN AND METHODS

In a historical prospective cohort study of subjects from the Clalit Health Services database, which includes information on nearly 4 million people, diabetes-free subjects aged 40-70 years with serum 25-hydroxycholecalciferol (25-OHD) measurements available were followed for 2 years to assess the development of IFG and diabetes in five 25-OHD subgroups: ≥25, 25.1-37.5, 37.6-50, 50.1-75, and >75 nmol/L.

RESULTS

The baseline cohort included 117,960 adults: 83,526 normoglycemic subjects and 34,434 subjects with IFG. During follow-up, 8,629 subjects (10.3% of the normoglycemic group) developed IFG, and 2,162 subjects (1.8% of the total cohort) progressed to diabetes. A multivariable model adjusted for age, sex, population group, immigrant status, BMI, season of vitamin D measurement, LDL and HDL cholesterol, triglycerides, estimated glomerular filtration rate, history of hypertension or cardiovascular disease, Charlson comorbidity index, smoking, and socioeconomic status revealed an inverse association between 25-OHD and the risk of progression to IFG and diabetes. The odds of transitioning from normoglycemia to IFG, from normoglycemia to diabetes, and from IFG to diabetes in subjects with a 25-OHD level ≤25 nmol/L were greater than those of subjects with a 25-OHD level >75 nmol/L [odds ratio 1.13 (95% CI 1.03-1.24), 1.77 (1.11-2.83), and 1.43 (1.16-1.76), respectively].

CONCLUSIONS

Vitamin D deficiency appears to be an independent risk factor for the development of IFG and diabetes.

The effect of vitamin D status on risk factors for cardiovascular disease

Vitamin-D-related pathways are implicated in various endocrine, inflammatory and endothelial functions. An estimated 1 billion people in the world have vitamin D deficiency or insufficiency, and undiagnosed vitamin D deficiency is common. Vitamin D deficiency is associated with substantial increases in the incidence of hypertension, hyperlipidaemia, myocardial infarction and stroke, as well as in diseases such as chronic kidney disease and type 2 diabetes. Low vitamin D levels also upregulate the renin-angiotensin-aldosterone system, increase inflammation and cause endothelial dysfunction. However, the role of vitamin D deficiency in cardiovascular morbidity and mortality is an emerging and hotly debated topic. Epidemiological studies suggest an association between low vitamin D levels and risk factors for cardiovascular disease, but a causal relationship has not been established, and clinical trials and meta-analyses have not demonstrated convincing evidence that vitamin D therapy improves cardiovascular outcomes. Some evidence suggests that vitamin D status is a biomarker of lifestyle, since unhealthy and sedentary lifestyles are associated with vitamin D insufficiency or deficiency and are also risk factors for cardiovascular complications.

Circulating biomarkers for predicting cardiovascular disease risk; a systematic review and comprehensive overview of meta-analyses

BACKGROUND

Cardiovascular disease is one of the major causes of death worldwide. Assessing the risk for cardiovascular disease is an important aspect in clinical decision making and setting a therapeutic strategy, and the use of serological biomarkers may improve this. Despite an overwhelming number of studies and meta-analyses on biomarkers and cardiovascular disease, there are no comprehensive studies comparing the relevance of each biomarker. We performed a systematic review of meta-analyses on levels of serological biomarkers for atherothrombosis to compare the relevance of the most commonly studied biomarkers.

METHODS AND FINDINGS

Medline and Embase were screened on search terms that were related to "arterial ischemic events" and "meta-analyses". The meta-analyses were sorted by patient groups without pre-existing cardiovascular disease, with cardiovascular disease and heterogeneous groups concerning general populations, groups with and without cardiovascular disease, or miscellaneous. These were subsequently sorted by end-point for cardiovascular disease or stroke and summarized in tables. We have identified 85 relevant full text articles, with 214 meta-analyses. Markers for primary cardiovascular events include, from high to low result: C-reactive protein, fibrinogen, cholesterol, apolipoprotein B, the apolipoprotein A/apolipoprotein B ratio, high density lipoprotein, and vitamin D. Markers for secondary cardiovascular events include, from high to low result: cardiac troponins I and T, C-reactive protein, serum creatinine, and cystatin C. For primary stroke, fibrinogen and serum uric acid are strong risk markers. Limitations reside in that there is no acknowledged search strategy for prognostic studies or meta-analyses.

CONCLUSIONS

For primary cardiovascular events, markers with strong predictive potential are mainly associated with lipids. For secondary cardiovascular events, markers are more associated with ischemia. Fibrinogen is a strong predictor for primary stroke.

Circulating biomarkers for predicting cardiovascular disease risk; a systematic review and comprehensive overview of meta-analyses

BACKGROUND

Cardiovascular disease is one of the major causes of death worldwide. Assessing the risk for cardiovascular disease is an important aspect in clinical decision making and setting a therapeutic strategy, and the use of serological biomarkers may improve this. Despite an overwhelming number of studies and meta-analyses on biomarkers and cardiovascular disease, there are no comprehensive studies comparing the relevance of each biomarker. We performed a systematic review of meta-analyses on levels of serological biomarkers for atherothrombosis to compare the relevance of the most commonly studied biomarkers.

METHODS AND FINDINGS

Medline and Embase were screened on search terms that were related to "arterial ischemic events" and "meta-analyses". The meta-analyses were sorted by patient groups without pre-existing cardiovascular disease, with cardiovascular disease and heterogeneous groups concerning general populations, groups with and without cardiovascular disease, or miscellaneous. These were subsequently sorted by end-point for cardiovascular disease or stroke and summarized in tables. We have identified 85 relevant full text articles, with 214 meta-analyses. Markers for primary cardiovascular events include, from high to low result: C-reactive protein, fibrinogen, cholesterol, apolipoprotein B, the apolipoprotein A/apolipoprotein B ratio, high density lipoprotein, and vitamin D. Markers for secondary cardiovascular events include, from high to low result: cardiac troponins I and T, C-reactive protein, serum creatinine, and cystatin C. For primary stroke, fibrinogen and serum uric acid are strong risk markers. Limitations reside in that there is no acknowledged search strategy for prognostic studies or meta-analyses.

CONCLUSIONS

For primary cardiovascular events, markers with strong predictive potential are mainly associated with lipids. For secondary cardiovascular events, markers are more associated with ischemia. Fibrinogen is a strong predictor for primary stroke.

Is hypovitaminosis D associated with abdominal aortic aneurysm, and is there a dose-response relationship?

OBJECTIVE

This study aims to investigate the association between plasma 25-hydroxyvitamin D (25(OH)D) concentrations with the presence of abdominal aortic aneurysm (AAA) and aortic diameter.

DESIGN

An observational study of 4233 community-dwelling men aged 70-88 years, who participated in a randomised controlled trial of screening for AAA.

METHODS

Infrarenal aortic diameter measured by ultrasound and 25(OH)D by immunoassay.

RESULTS

A total of 311 men (7.4%) with AAA (defined as aortic diameter ≥ 30 mm) comprised the study. Multivariable models were adjusted for age, smoking, cardiovascular disease, hypertension, diabetes, dyslipidaemia, body mass index and serum creatinine concentration. Amongst men with the lowest 25(OH)D quartile of values compared with the highest quartile, the adjusted odds ratio of having an AAA increased in a graded fashion from 1.23 (95% confidence interval (CI) 0.87-1.73) for AAA ≥ 30 mm to 5.42 (95% CI 1.85-15.88) for AAA ≥ 40 mm. Similarly, there was a dose-response relationship between 25(OH)D concentrations and the size of the AAA: every 10-nmol l(-1) decrease in 25(OH)D levels was associated with 0.49 mm (95% CI 0.11-0.87) increase in mean aortic diameter.

CONCLUSIONS

Low vitamin D status is associated with the presence of larger AAA in older men, and there is a graded inverse relationship between 25(OH)D concentrations and AAA diameter. Further research is needed to clarify the mechanisms underlying these associations.

25-OH-Vitamin D and procalcitonin levels after correction of acute hyperglycemia

BACKGROUND

Hyperglycemia is a common complication of diabetes melitis (DM) and in the absence of metabolic decompensation is a common finding in the Emergency Department (ED). We aimed to evaluate the 25 OH Vit D [25(OH)D] and procalcitonin (PCT) levels during hyperglycemia and after normalization of blood glucose.

MATERIAL AND METHODS

The study included 88 patients over the age of 18 years who presented with acute hyperglycemia at the Hacettepe University Department of Emergency Medicine. Euglycemia was obtained within 6-12 hours and serum samples were taken from patients on admission and 6 hours after normalization of blood glucose. Along with plasma glucose, plasma 25(OH)D and PCT levels were measured using ELISA.

RESULTS

There were 88 (45 males) patients, with a median age of 60.0±13.9 years. Serum 25(OH)D levels increased in all patients after normalization of blood glucose, and serum PCT levels decreased in the whole group. This decrease was independent of type of diabetes or presence of infection.

CONCLUSIONS

We demonstrated an increase in 25(OH)D after normalization of blood glucose, and a decrease in PCT in patients with hyperglycemia. This effect was independent of the type of diabetes and presence of infection. Further studies are needed to evaluate the faster link between metabolic abnormalities, vitamin D, PCT, and inflammation.

Effect of vitamin D supplementation on blood pressure in blacks

Blacks have significantly higher rates of hypertension than whites, and lower circulating levels of 25-hydroxyvitamin D. There are few data about the effect of vitamin D3 (cholecalciferol) supplementation on blood pressure in blacks. During 2 winters from 2008 to 2010, 283 blacks (median age, 51 years) were randomized into a 4-arm, double-blind trial for 3 months of placebo, 1000, 2000, or 4000 international units of cholecalciferol per day. At baseline, 3 months, and 6 months, systolic and diastolic pressure and 25-hydroxyvitamin D were measured. The 3-month follow-up was completed in 250 (88%) participants. The difference in systolic pressure between baseline and 3 months was +1.7 mm Hg for those receiving placebo, -0.66 mm Hg for 1000 U/d, -3.4 mm Hg for 2000 U/d, and -4.0 mm Hg for 4000 U/d of cholecalciferol (-1.4 mm Hg for each additional 1000 U/d of cholecalciferol; P=0.04). For each 1-ng/mL increase in plasma 25-hydroxyvitamin D, there was a significant 0.2-mm Hg reduction in systolic pressure (P=0.02). There was no effect of cholecalciferol supplementation on diastolic pressure (P=0.37). Within an unselected population of blacks, 3 months of oral vitamin D3 supplementation significantly, yet modestly, lowered systolic pressure. Future trials of vitamin D supplementation on blood pressure are needed to confirm these promising results, particularly among blacks, a population for whom vitamin D deficiency may play a more specific mechanistic role in the pathogenesis of hypertension.

Vitamin D deficiency in medical patients at a central hospital in Malawi: a comparison with TB patients from a previous study

Objectives

To determine the prevalence of vitamin D deficiency (VDD) in adult medical, non-tuberculous (non-TB) patients. To investigate associations with VDD. To compare the results with a similar study in TB patients at the same hospital.

Design

Cross-sectional sample.

Setting

Central hospital in Malawi.

Participants

Adult non-TB patients (n = 157), inpatients and outpatients.

Outcome Measures

The primary outcome was the prevalence of VDD. Potentially causal associations sought included nutritional status, in/outpatient status, HIV status, anti-retroviral therapy (ART) and, by comparison with a previous study, a diagnosis of tuberculosis (TB).

Results

Hypovitaminosis D (≤75 nmol/L) occurred in 47.8% (75/157) of patients, 16.6% (26/157) of whom had VDD (≤50 nmol/L). None had severe VDD (≤25 nmol/L). VDD was found in 22.8% (23/101) of in-patients and 5.4% (3/56) of out-patients. In univariable analysis in-patient status, ART use and low dietary vitamin D were significant predictors of VDD. VDD was less prevalent than in previously studied TB patients in the same hospital (68/161 = 42%). In multivariate analysis of the combined data set from both studies, having TB (OR 3.61, 95%CI 2.02–6.43) and being an in-patient (OR 2.70, 95%CI 1.46–5.01) were significant independent predictors of VDD.

Conclusions

About half of adult medical patients without TB have suboptimal vitamin D status, which is more common in in-patients. VDD is much more common in TB patients than non-TB patients, even when other variables are controlled for, suggesting that vitamin D deficiency is associated with TB.

Association of low serum 25-hydroxyvitamin D levels in pregnancy with glucose homeostasis and obstetric and newborn outcomes

OBJECTIVE

To evaluate the association of maternal serum 25-hydroxyvitamin D (25[OH]D) status with glucose homeostasis and obstetric and newborn outcomes in women screened for gestational diabetes mellitus (GDM).

METHODS

Consecutive women were screened for GDM at 24 to 28 weeks' gestation during the months of maximal sunlight exposure in Spain (June through September). Serum 25(OH)D levels and parameters of glucose homeostasis were measured. Outcomes of the delivery and newborn were collected.

RESULTS

Two hundred sixty-six women were screened. Vitamin D deficiency (25[OH]D <20 ng/mL) was observed in 157 women (59%). We observed an inverse correlation between 25(OH)D levels and hemoglobin A1c, homeostasis model assessment of insulin resistance, serum insulin, and fasting and 1-hour oral glucose tolerance test glucose levels (P<.001). With a 25(OH)D concentration less than 20 ng/mL, the odds ratios were 3.31 for premature birth (95% confidence interval, 1.52-7.19; P<.002) and 3.93 for cesarean delivery (95% confidence interval, 2.00-7.73; P<.001). A 25(OH)D concentration of 20 ng/mL had 79% sensitivity and 51% specificity for cesarean delivery and 80% sensitivity and 45% specificity for premature birth. The cutoffs with the best combination of sensitivity and specificity were 16 ng/mL for cesarean delivery (62.9% sensitivity and 61.2% specificity) and 14 ng/mL for premature birth (66.7% sensitivity and 71.0% specificity).

CONCLUSIONS

In the population we sampled, vitamin D deficiency is very common during pregnancy. Lower 25(OH)D levels are associated with disorders of glucose homeostasis and adverse obstetric and newborn outcomes.

Plasma 25-hydroxyvitamin D, hormonal contraceptive use, and the plasma proteome in Caucasian, East Asian, and South Asian young adults

Vitamin D affects gene expression, but its downstream effects on the proteome are unclear. Hormonal contraceptives (HC), which affect vitamin D metabolism and have widespread effects on the plasma proteome, may confound the association between vitamin D and the proteome. We determined whether HC use modified the association between 25-hydroxyvitamin D (25D) and a panel of 54 high-abundance plasma proteins. Cross-sectional analyses were conducted in healthy, nonsmoking female HC users (n = 216), female HC nonusers (n = 502), and men (n = 301) from Toronto, Canada. Plasma 25D was measured by HPLC-MS/MS, and proteins were measured by LC-multiple-reaction-monitoring (MRM)-MS. The 54 proteins clustered into four distinct proteomic profiles. A positive association was observed between Profile 1, containing positive acute phase proteins, and 25D. In female HC users, a J-shaped association existed between Profile 1 and 25D, but no associations existed in female HC nonusers and men. Twelve proteins were individually associated with 25D in female HC users, but only two were associated with 25D in female HC nonusers and no associations were observed in men. After accounting for hormone dose, only three proteins were associated with 25D. In summary, HC use is an important confounder of the association between circulating 25D and numerous plasma proteins.

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 receptor gene polymorphism and cardiovascular risk variables in elderly Polish subjects

The aim of this work was to evaluate whether the FokI and BsmI polymorphisms of the VDR gene are associated with anthropometric and biochemical features of cardiovascular disease (CVD) in a Caucasian population aged over 65, participants of the Polish PolSenior study. We performed the study on randomly selected subjects: 427 women and 454 men aged over 65. Measurements of anthropometric parameters were carried out and biochemical parameters were estimated using commercial kits. VDR polymorphisms (rs10735810, rs1544410) were genotyped by PCR and FRLP. The prevalence of BsmI genotypes was 50% Bb, 23% bb, 27% BB in women and 48% Bb, 20% bb, 32% BB in men. The prevalence of FokI was 48% Ff, 22% ff, 30% FF in women and 50% Ff, 18% ff, 32% FF in men. The women bearing the rare allele b differ in homeostatic model assessment (HOMA) (p < 0.049) from women bearing common allele B, and the men differ in insulin level (p < 0.047) and HOMA (p < 0.017). There were no significant differences in anthropometric or biochemical parameters between genotypes in FokI in female and male groups. The common allele B is connected with biochemical risk factors of CVD in older Caucasian men and women.

Serum 25-hydroxyvitamin D levels and overall mortality. A systematic review and meta-analysis of prospective cohort studies

OBJECTIVE

To provide a systematic review and meta-analysis of prospective, population-based cohort studies on the association of serum 25-hydroxyvitamin D (25(OH)D) and all-cause mortality.

METHODS

Relevant studies were identified by systematically searching Medline, EMBASE and ISI Web of Knowledge. Reported hazard ratios (HRs) for 25(OH)D categories were recalculated employing comprehensive trend estimation from summarized dose-response data and pooled in a random effects model meta-analysis.

RESULTS

Overall, 12 original studies were included in the review and meta-analysis comprising 32,142 mainly elderly study participants with measured 25(OH)D of whom 6921 died during follow-up. An inverse association between 25(OH)D levels and all-cause mortality was found in all but two studies that was statistically significant in several of the individual studies. In meta-analysis, 25(OH)D levels were significantly inversely associated with all-cause mortality with a pooled HR of 0.92 (95% confidence interval: 0.89-0.95) for a 20 nmol/l increase in 25(OH)D levels.

CONCLUSION

In this meta-analysis of prospective, population-based cohort studies, a 20 nmol/l increase in 25(OH)D levels was associated with an 8% lower mortality in the general elderly population. This agrees with results from meta-analyses on randomized controlled trials that found a decrease in mortality with vitamin D3 supplementation of a comparable magnitude.

The influence of selective vitamin D receptor activator paricalcitol on cardiovascular system and cardiorenal protection

The ubiquitous distribution of vitamin D receptors in the human body is responsible for the pleiotropic effects of vitamin D-receptor activation. We discuss the possible beneficial effects of a selective activator of vitamin D receptor, paricalcitol, on the cardiovascular system in chronic heart failure patients and chronic kidney patients, in light of new trials. Paricalcitol should provide additional clinical benefits over the standard treatment for chronic kidney and heart failure, especially in cases of cardiorenal syndrome.

Genetic regulation of vitamin D levels

Vitamin D plays several roles in the body, influencing bone health as well as serum calcium and phosphate levels. Further, vitamin D may modify immune function, cell proliferation, differentiation, and apoptosis. Vitamin D deficiency has been associated with numerous health outcomes, including bone disease, cancer, autoimmune disease, infectious disease, type 1 and type 2 diabetes, hypertension, and heart disease, although it is unclear whether or not these associations are causal. Various twin and family studies have demonstrated moderate to high heritability for circulating vitamin D levels. Accordingly, many studies have investigated the genetic determinants of this hormone. Recent advances in the methodology of large-scale genetic association studies, including coordinated international collaboration, have identified associations of CG, DHCR1, CYP2R1, VDR, and CYP24A1 with serum levels of vitamin D. Here, we review the genetic determinants of vitamin D levels by focusing on new findings arising from candidate gene and genomewide association studies.

Health benefits of seafood; is it just the fatty acids?

There is a considerable body of literature suggesting a wide range of health benefits associated with diets high in seafood. However, the demand for seafood across the world now exceeds that available from capture fisheries. This has created a rapidly increasing market for aquaculture products, the nutrient composition of which is dependent on feed composition. The use of fishmeal in this food chain does little to counteract the environmental impact of fisheries and so the on-going development of alternative sources is to be welcomed. Nevertheless, an in-depth understanding as to which nutrients in seafood provide benefit is required to permit the production of foods of maximal health benefit to humans. This paper reviews our current knowledge of the beneficial nutrient composition of seafood, in particular omega-3 fatty acids, selenium, taurine, vitamins D and B12, in the context of the development of environmentally sustainable aquaculture.

Efficacy of vitamin and antioxidant supplements in prevention of cardiovascular disease: systematic review and meta-analysis of randomised controlled trials

OBJECTIVE

To assess the efficacy of vitamin and antioxidant supplements in the prevention of cardiovascular diseases.

DESIGN

Meta-analysis of randomised controlled trials.

DATA SOURCES AND STUDY SELECTION

PubMed, EMBASE, the Cochrane Library, Scopus, CINAHL, and ClinicalTrials.gov searched in June and November 2012. Two authors independently reviewed and selected eligible randomised controlled trials, based on predetermined selection criteria.

RESULTS

Out of 2240 articles retrieved from databases and relevant bibliographies, 50 randomised controlled trials with 294,478 participants (156,663 in intervention groups and 137,815 in control groups) were included in the final analyses. In a fixed effect meta-analysis of the 50 trials, supplementation with vitamins and antioxidants was not associated with reductions in the risk of major cardiovascular events (relative risk 1.00, 95% confidence interval 0.98 to 1.02; I(2)=42%). Overall, there was no beneficial effect of these supplements in the subgroup meta-analyses by type of prevention, type of vitamins and antioxidants, type of cardiovascular outcomes, study design, methodological quality, duration of treatment, funding source, provider of supplements, type of control, number of participants in each trial, and supplements given singly or in combination with other supplements. Among the subgroup meta-analyses by type of cardiovascular outcomes, vitamin and antioxidant supplementation was associated with a marginally increased risk of angina pectoris, while low dose vitamin B(6) supplementation was associated with a slightly decreased risk of major cardiovascular events. Those beneficial or harmful effects disappeared in subgroup meta-analysis of high quality randomised controlled trials within each category. Also, even though supplementation with vitamin B(6) was associated with a decreased risk of cardiovascular death in high quality trials, and vitamin E supplementation with a decreased risk of myocardial infarction, those beneficial effects were seen only in randomised controlled trials in which the supplements were supplied by the pharmaceutical industry.

CONCLUSION

There is no evidence to support the use of vitamin and antioxidant supplements for prevention of cardiovascular diseases.

Association of vitamin D with cardiometabolic risk factors in rheumatoid arthritis

OBJECTIVE

Individuals with rheumatoid arthritis (RA) are at a greater risk for cardiovascular disease (CVD). Vitamin D deficiency is a potential risk factor for CVD and metabolic syndrome. Since patients with RA have a high prevalence of vitamin D deficiency, we investigated the association of vitamin D levels with cardiometabolic risk factors in a cohort of RA patients with no prior history of CVD.

METHODS

Serum 25-hydroxyvitamin D (25[OH]D) levels were measured among RA patients enrolled in a cohort study of subclinical CVD. The cross-sectional associations of 25(OH)D levels with traditional CVD risk factors such as insulin resistance (IR; estimated using the homeostatic model assessment [HOMA]), adipokines, markers of systemic inflammation, and endothelial activation were explored, adjusting for pertinent sociodemographic, lifestyle, and RA characteristics.

RESULTS

Among 179 RA patients, 73 (41%) had a 25(OH)D level <30 ng/ml. Only 23 patients (13%) had a 25(OH)D level ≥45 ng/ml. After adjusting for demographics and body mass index (BMI), 25(OH)D remained significantly associated with high-density lipoprotein (HDL) cholesterol and inversely associated with HOMA-IR, fibrinogen, E-selectin, and soluble intercellular adhesion molecule 1 (sICAM-1). Significant associations with HDL cholesterol, E-selectin, and sICAM-1 were maintained after adjusting for the Disease Activity Score in 28 joints (DAS28) and autoantibody status. These associations were similar between the groups subdivided by sex, ethnicity, BMI, DAS28 level, and autoantibody status.

CONCLUSION

These data suggest that vitamin D deficiency is common in RA and may be independently associated with several cardiometabolic intermediates in this population.

Vitamin D - effects on skeletal and extraskeletal health and the need for supplementation

Vitamin D, the sunshine vitamin, has received a lot of attention recently as a result of a meteoric rise in the number of publications showing that vitamin D plays a crucial role in a plethora of physiological functions and associating vitamin D deficiency with many acute and chronic illnesses including disorders of calcium metabolism, autoimmune diseases, some cancers, type 2 diabetes mellitus, cardiovascular disease and infectious diseases. Vitamin D deficiency is now recognized as a global pandemic. The major cause for vitamin D deficiency is the lack of appreciation that sun exposure has been and continues to be the major source of vitamin D for children and adults of all ages. Vitamin D plays a crucial role in the development and maintenance of a healthy skeleton throughout life. There remains some controversy regarding what blood level of 25-hydroxyvitamin D should be attained for both bone health and reducing risk for vitamin D deficiency associated acute and chronic diseases and how much vitamin D should be supplemented.

Cholecalciferol administration blunts the systemic renin-angiotensin system in essential hypertensives with hypovitaminosis D

INTRODUCTION

Vitamin D plasma levels are negatively associated with blood pressure and cardiovascular mortality, and vitamin D supplementation reduces cardiovascular events. Renin-angiotensin system (RAS) suppression may be one of the mechanisms involved. However, there are no interventional prospective studies demonstrating a reduction in circulating RAS components after vitamin D treatment.

METHODS

Fifteen consecutive drug-free patients with essential hypertension and hypovitaminosis D underwent therapy with an oral dose of 25000 I.U. of cholecalciferol once a week for two months, while maintaining a constant-salt diet. In basal conditions and at the end of the study, RAS activity (plasma angiotensinogen, renin, PRA, angiotensin II, aldosterone and urinary angiotensinogen) was investigated, in addition to blood pressure and plasma vitamin D levels (25(OH)D).

RESULTS

After cholecalciferol administration, all patients exhibited normalized plasma 25(OH)D values. At the end of the study, a reduction (p < 0.05) in plasma renin and aldosterone, and a decrement, although not significant, of PRA and angiotensin II, was observed. No difference was found in plasma and urinary angiotensinogen or blood pressure values.

CONCLUSIONS

Our data indicate that in essential hypertensives with hypovitaminosis D, pharmacological correction of vitamin D levels can blunt systemic RAS activity.

Protective cardiovascular and renal actions of vitamin D and estrogen

Both basic science and clinical studies support the concept that vitamin D deficiency is involved in the pathogenesis of cardiovascular and renal diseases through its association with diabetes, obesity, and hypertension. Understanding the underlying mechanisms may provide a rationale for advocating adequate intake of vitamin D and calcium in all populations, thereby preventing many chronic diseases. This review explores the effect of vitamin D deficiency in the development of cardiovascular and renal diseases, and the role of vitamin D supplementation on cardiovascular outcomes. In addition, it highlights the importance of vitamin D intake for the prevention of adverse long-term health consequences, and in ways to facilitate the management of cardiovascular disease. This is particularly true for African American and postmenopausal women, who are at added risk for cardiovascular disease. We suggest that the negative cardiovascular effects of low vitamin D in postmenopausal women could be improved by a combined treatment of vitamin D and sex steroids acting through endothelium-dependent and/or -independent mechanisms, resulting in the generation of nitric oxide and calcitonin gene-related peptide (CGRP).

Randomized controlled trial of vitamin D supplement on endothelial function in patients with type 2 diabetes

BACKGROUND

Suboptimal vitamin D status is associated with endothelial dysfunction and an increased risk of cardiovascular diseases but it is unclear whether vitamin D supplementation is beneficial. The aim was to investigate the effect of vitamin D supplementation on endothelial function in patients with type 2 diabetes mellitus (DM).

METHODS

In a double-blind, placebo-controlled trial, we randomized 100 type 2 DM patients to vitamin D supplement (5000 IU/day, n = 50) or placebo (controls, n = 50) for 12 weeks. Assessment of vascular function with brachial artery flow-mediated dilatation (FMD), circulating levels of endothelial progenitor cells (EPCs) and brachial-ankle pulse wave velocity, and metabolic parameter, high-sensitivity C-reactive protein (hsCRP) and oxidative stress markers were performed before and after the supplementation.

RESULTS

After 12 weeks, vitamin D treated patients had significant increases in serum 25-hydroxyvitamin D [25(OH)D] concentration (treatment effect 34.7 ng/mL, 95% CI 26.4-42.9, P < 0.001) and serum ionized calcium (treatment effect 0.037 mmol/L, 95% CI 0.007-0.067, P = 0.018); decreased serum parathyroid hormone concentration (treatment effect -0.55 pmol/L, 95% CI -1.08 to -0.02, P = 0.042) compared to patients who received placebo. Nevertheless, vitamin D supplementation did not improve vascular function as determined by FMD, circulating EPC count or baPWV (all P > 0.05). Furthermore, hsCRP, oxidative stress markers, low- and high-density lipoprotein and glycated hemoglobin were also similar between two groups (all P > 0.05).

CONCLUSION

In patients with type 2 DM, 12 weeks oral supplementation of vitamin D did not significantly affect vascular function or serum biomarkers of inflammation and oxidative stress.

CLINICAL TRIAL NUMBER

HKCTR-867, www.hkclinicaltrials.com.

Hypovitaminosis D and peripheral arterial disease: emerging link beyond cardiovascular risk factors

Vitamin D has received increasing interest for its beneficial effect on health. Beyond its conventional role in bone metabolism, emerging evidence suggests a possible link between low vitamin D levels and cardiovascular disease (CVD), including peripheral arterial disease (PAD), and cardiovascular risk factors. Vitamin D interacts either directly with the vascular tree or indirectly through its association with cardiovascular risk factors, but the exact mechanism remains controversial. This review outlines the association between hypovitaminosis D and PAD. Both entities are quite prevalent in the general population and, therefore, their potential association might have important clinical implications. Whether vitamin D deficiency represents a novel risk factor for PAD/CVD, and whether vitamin D supplementation would reduce the burden of CVD still remains to be answered. Until then, vitamin D intake is not recommended for PAD/CVD prevention. Outdoor physical activity, coupled with adequate but safe sun exposure, is a healthy lifestyle practice suggested for the prevention of both PAD and hypovitaminosis D.

Vitamin D and overall mortality

Vitamin D is a steroid molecule, mainly produced in the skin that regulates the expression of a large number of genes. Several meta-analyses of epidemiological studies support the evidence that low vitamin D serum level, which is highly prevalent worldwide, could be a 'new' risk factor for many chronic diseases including cancer, and for all-cause mortality. A meta-analysis in healthy subjects suggested that current doses of vitamin D supplements could be associated with decrease in total mortality rates. However, these associations are insufficient to establish causality between vitamin D and all-cause mortality. Furthermore, long-term health effects of high doses of vitamin D, that is, prolonged supplementation and association with different baseline vitamin D levels, remain to be investigated. Several trials are ongoing but population-based, placebo-controlled randomized trials with total mortality as the main endpoint should be planned to confirm a real beneficial effect of vitamin D for non-skeletal diseases and to prove causality.

Levels of 25-hydroxyvitamin D in familial longevity: the Leiden Longevity Study

BACKGROUND

Low levels of 25(OH) vitamin D are associated with various age-related diseases and mortality, but causality has not been determined. We investigated vitamin D levels in the offspring of nonagenarians who had at least one nonagenarian sibling; these offspring have a lower prevalence of age-related diseases and a higher propensity to reach old age compared with their partners.

METHODS

We assessed anthropometric characteristics, 25(OH) vitamin D levels, parathyroid hormone levels, dietary vitamin D intake and single nucleotide polymorphisms (SNPs) associated with vitamin D levels. We included offspring (n = 1038) of nonagenarians who had at least one nonagenarian sibling, and the offsprings' partners (n = 461; controls) from the Leiden Longevity Study. We included age, sex, body mass index, month during which blood sampling was performed, dietary and supplemental vitamin D intake, and creatinine levels as possible confounding factors.

RESULTS

The offspring had significantly lower levels of vitamin D (64.3 nmol/L) compared with controls (68.4 nmol/L; p = 0.002), independent of possible confounding factors. There was no difference in the levels of parathyroid hormone between groups. Compared with controls, the offspring had a lower frequency of a genetic variant in the CYP2R1 gene (rs2060793) (p = 0.04). The difference in vitamin D levels between offspring and controls persisted over the 2 most prevalent genotypes of this SNP.

INTERPRETATION

Compared with controls, the offspring of nonagenarians who had at least one nonagenarian sibling had a reduced frequency of a common variant in the CYP2R1 gene, which predisposes people to high vitamin D levels; they also had lower levels of vitamin D that persisted over the 2 most prevalent genotypes. These results cast doubt on the causal nature of previously reported associations between low levels of vitamin D and age-related diseases and mortality.

Evidence-based D-bate on health benefits of vitamin D revisited

Vitamin D has received worldwide attention not only for its importance for bone health in children and adults but also for reducing risk for many chronic diseases including autoimmune diseases, type 2 diabetes, heart disease, many cancers and infectious diseases. Vitamin D deficiency is pandemic due to the fact that most humans have depended on sun for their vitamin D requirement which they now either avoid or wear sun protection for fear of skin cancer. There are few foods that naturally contain vitamin D. Some countries permit vitamin D fortification especially dairy products, some cereals and juice products. The Institute of Medicine made its recommendations based on a population-based model; the Endocrine Society's Practice Guidelines on Vitamin D was for the prevention and treatment of vitamin D deficiency, which helps explain the differences in the recommendations. The Guidelines defined vitamin D deficiency as a 25-hydroxyvitamin D < 20 ng/mL, insufficiency as 21-29 ng/mL and sufficiency as 30-100 ng/mL. To prevent vitamin D deficiency The Guidelines recommended vitamin D intake should be: children < 1 y 400-1,000 IU/d, children 1-18 y 600-1,000 IU/d and adults 1,500-2,000 IU/d.

Beneficial effects of UV radiation other than via vitamin D production

Most of the positive effects of solar radiation are mediated via ultraviolet-B (UVB) induced production of vitamin D in skin. However, several other pathways may exist for the action of ultraviolet (UV) radiation on humans as focused on in this review. One is induction of cosmetic tanning (immediate pigment darkening, persistent pigment darkening and delayed tanning). UVB-induced, delayed tanning (increases melanin in skin after several days), acts as a sunscreen. Several human skin diseases, like psoriasis, vitiligo, atopic dermatitis and localized scleroderma, can be treated with solar radiation (heliotherapy) or artificial UV radiation (phototherapy). UV exposure can suppress the clinical symptoms of multiple sclerosis independently of vitamin D synthesis. Furthermore, UV generates nitric oxide (NO), which may reduce blood pressure and generally improve cardiovascular health. UVA-induced NO may also have antimicrobial effects and furthermore, act as a neurotransmitter. Finally, UV exposure may improve mood through the release of endorphins.

Vitamin D deficiency in postmenopausal, healthy women predicts increased cardiovascular events: a 16-year follow-up study

OBJECTIVE

To investigate the relationship between vitamin D status in healthy women and cardiovascular outcome.

DESIGN AND METHODS

Between 1990 and 1993, 2016 healthy, recently postmenopausal women were enrolled in the Danish Osteoporosis Prevention Study. Serum levels of 25-hydroxyvitamin D (25(OH)D, nmol/l) were measured at baseline. Participants were followed for 16 years. The primary end point was a combination of death, heart failure, myocardial infarction (MI) and stroke. Vitamin D deficiency was defined as serum 25(OH)D<50 nmol/l. The primary end point was adjusted for other risk factors of adverse cardiovascular events (age, smoking, blood pressure, hip-waist ratio, education and family history of MI).

RESULTS

At baseline, mean age was 50 years and BMI 25. Women with vitamin D deficiency (n=788) had more cardiovascular risk factors than vitamin D-replete women (n=1225). Compared with vitamin D-replete women, women with low 25(OH)D levels had significantly higher BMI and triglycerides, lower HDL and hip-waist ratio and less education. More were smokers among the vitamin D deficient (47 vs 38%). A primary end point was experienced by 118 (15%) with vitamin D deficiency and by 125 (10%) of the vitamin D replete. Hazard ratio (HR) was 1.49 (95% confidence interval: 1.16-1.92; P=0.002) in the vitamin D deficient. Adjusted HR was 1.32 (1.02-1.71; P=0.03). In total, 135 women died; of these, 65 (8%) were of the vitamin D deficient and 70 (6%) in the vitamin D-replete group; unadjusted HR was 1.44 (1.02-2.01; P=0.04) for vitamin D deficiency.

CONCLUSION

Healthy women with vitamin D deficiency have increased risk of adverse cardiovascular outcome.

High-dose cholecalciferol reduces parathyroid hormone in patients with early chronic kidney disease: a pilot, randomized, double-blind, placebo-controlled trial

BACKGROUND

Vitamin D deficiency contributes to secondary hyperparathyroidism, which occurs early in chronic kidney disease (CKD).

OBJECTIVES

We aimed to determine whether high-dose cholecalciferol supplementation for 1 y in early CKD is sufficient to maintain optimal vitamin D status (serum 25-hydroxyvitamin D [25(OH)D] concentration ≥30 ng/mL) and decrease serum parathyroid hormone (PTH). A secondary aim was to determine the effect of cholecalciferol on blood pressure and serum fibroblast growth factor-23 (FGF23).

DESIGN

This was a double-blind, randomized, placebo-controlled trial. Forty-six subjects with early CKD (stages 2-3) were supplemented with oral cholecalciferol (vitamin D group; 50,000 IU/wk for 12 wk followed by 50,000 IU every other week for 40 wk) or a matching placebo for 1 y.

RESULTS

By 12 wk, serum 25(OH)D increased in the vitamin D group only [baseline (mean ± SD): 26.7 ± 6.8 to 42.8 ± 16.9 ng/mL; P < 0.05] and remained elevated at 1 y (group-by-time interaction: P < 0.001). PTH decreased from baseline only in the vitamin D group (baseline: 89.1 ± 49.3 to 70.1 ± 24.8 pg/mL; P = 0.01) at 12 wk, but values were not significantly different from baseline at 1 y (75.4 ± 29.5 pg/mL; P = 0.16; group-by-time interaction: P = 0.09). Group differences were more pronounced in participants with secondary hyperparathyroidism (group-by-time interaction: P = 0.004). Blood pressure and FGF23 did not change in either group.

CONCLUSIONS

After 1 y, this oral cholecalciferol regimen was safe and sufficient to maintain serum 25(OH)D concentrations and prevent vitamin D insufficiency in early CKD. Furthermore, serum PTH improved after cholecalciferol treatment, particularly in patients who had secondary hyperparathyroidism.