The role of vitamin D in cardiovascular disease: From present evidence to future perspectives

Vitamin D and Toxic Metals in Pregnancy - a Biological Perspective

Purpose of Review

To discuss the potential biological mechanisms between vitamin D and toxic metals and summarize epidemiological studies examining this association in pregnant women.

Recent Findings

We identified four plausible mechanisms whereby vitamin D and toxic metals may interact: nephrotoxicity, intestinal absorption of metals, endocrine disruption, and oxidative stress. Few studies have examined the association between vitamin D and toxic metals in pregnant women. North American studies suggest that higher vitamin D status early in pregnancy are associated with lower blood metals later in pregnancy. However, a trial of vitamin D supplementation in a pregnant population, with higher metal exposures and lower overall nutritional status, does not corroborate these findings.

Summary

Given ubiquitous exposure to many toxic metals, nutritional intervention could be a means for prevention of adverse outcomes. Future prospective studies are needed to establish a causal relationship and clarify the directionality of vitamin D and metals.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40471-024-00348-0.

Nutrient patterns in relation to insulin resistance and endothelial dysfunction in Iranian women

Prior studies have mainly focused on the association of one specific nutrient with insulin resistance (IR) and endothelial dysfunction and limited studies have assessed the association with different nutrient patterns (NPs). We examined the association between various NPs and IR and endothelial dysfunction among Iranian women. This cross-sectional study was carried out on a sample of 368 female nurses. A 106-items food frequency questionnaire (FFQ) was applied for dietary assessments. Using factor analysis, the relationships between NPs and markers of insulin resistance (HOMA-IR, HOMA-β, and QUICKY), and endothelial dysfunction (E-selectin, sICAM-1, and sVCAM-1) were assessed. Mean age and body mass index of participants were respectively 35.21 years and 24.04 kg/m2. Three major NPs were identified. NP1, named as "dairy, fruits, and vegetables" had high values of potassium, folate, vitamins A and C, magnesium, and beta carotene. No significant association was observed between this NP and insulin resistance or endothelial dysfunction indices. The second NP was full of chromium, selenium, copper, vitamin B6, monounsaturated fatty acid (MUFA), thiamin, vitamin D, and iron. Adherence to NP2 (named "legumes, nuts, and protein foods") was associated with lower values of insulin (6.8 ± 1.1 versus 8.4 ± 1.1, P = 0.01), homeostasis model assessment-Insulin resistance (HOMA-IR) (1.3 ± 0.2 versus 1.7 ± 0.2, P = 0.02), and vascular adhesion molecule 1 (VCAM-1) (444.2 ± 27.9 versus 475.8 ± 28.4, P = 0.03). However, adherence to the third NP, rich in saturated fatty acid (SFA), cholesterol, sodium, zinc, vitamin E, and B12, described as "animal fat and meat + vitamin E", was associated with higher amounts of homeostasis model assessment-β (HOMA-β) (531.3 ± 176.2 versus 48.7 ± 179.8, P = 0.03). In conclusion, following the NP2, correlated with higher intakes of chromium, selenium, copper, vitamin B6, MUFA and thiamin was associated with lower values of insulin, HOMA-IR, and sVCAM-1. Adherence to NP3, rich in SFA, cholesterol, vitamin E, vitamin B12, and zinc was associated with higher levels of HOMA-β.

Relationship between vitamin D and coronary artery disease in Egyptian patients

BACKGROUND

Previous studies have reported conflicting results about the association of vitamin D (VD) level with coronary artery disease (CAD). We aimed to study the association of VD with atherosclerotic CAD in Egyptian individuals.

RESULTS

We prospectively enrolled 188 consecutive CAD patients with a median age of 55(50-62) years; 151(80.3%) were male. All patients were diagnosed by cardiac catheterization and were compared with 131 healthy controls. VD levels were measured in serum samples of all participants. Compared to controls, CAD patients had a significantly lower median VD level, 14.65 (9.25-21.45) versus 42.0 (32.0-53.0) ng/mL, p < 0.001. VD was correlated with the number of diseased coronary arteries and lipid profile (total cholesterol, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, and triglycerides, p < 0.001 for each). By multivariate analyses, VD was an independent predictor of CAD [OR 1.22 (95% CI 1.07-1.4), p = 0.003, optimal cut-off value 30 ng/mL (AUC 0.92, sensitivity 81% and specificity 81.4%), p < 0.001], and the number of diseased coronary arteries, p < 0.001, especially three-vessel disease [OR 0.83 (95% CI 0.72-0.95), p = 0.008].

CONCLUSIONS

We have shown that low VD should be considered a non-traditional risk factor for CAD in Egyptian individuals. Low VD was correlated with coronary atherosclerosis, especially in patients with multivessel effects.

The Role of Vitamin D and Its Molecular Bases in Insulin Resistance, Diabetes, Metabolic Syndrome, and Cardiovascular Disease: State of the Art

In the last decade, an increasing awareness was directed to the role of Vitamin D in non-skeletal and preventive roles for chronic diseases. Vitamin D is an essential hormone in regulating calcium/phosphorous balance and in the pathogenesis of inflammation, insulin resistance, and obesity. The main forms of vitamin D, Cholecalciferol (Vitamin D3) and Ergocalciferol (Vitamin D2) are converted into the active form (1,25-dihydroxyvitamin D) thanks to two hydroxylations in the liver, kidney, pancreas, and immune cells. Some anti-inflammatory cytokines are produced at higher levels by vitamin D, while some pro-inflammatory cytokines are released at lower levels. Toll-Like Receptor (TLR) expression is increased, and a pro-inflammatory state is also linked to low levels of vitamin D. Regardless of how it affects inflammation, various pathways suggest that vitamin D directly improves insulin sensitivity and secretion. The level of vitamin D in the body may change the ratio of pro- to anti-inflammatory cytokines, which would impact insulin action, lipid metabolism, and the development and function of adipose tissue. Many studies have demonstrated an inverse relationship between vitamin D concentrations and pro-inflammatory markers, insulin resistance, glucose intolerance, metabolic syndrome, obesity, and cardiovascular disease. It is interesting to note that several long-term studies also revealed an inverse correlation between vitamin D levels and the occurrence of diabetes mellitus. Vitamin D supplementation in people has controversial effects. While some studies demonstrated improvements in insulin sensitivity, glucose, and lipid metabolism, others revealed no significant effect on glycemic homeostasis and inflammation. This review aims to provide insight into the molecular basis of the relationship between vitamin D, insulin resistance, metabolic syndrome, type 1 and 2 diabetes, gestational diabetes, and cardiovascular diseases.

The critically low levels of vitamin D predicts the resolution of the ST-segment elevation after the primary percutaneous coronary intervention

AIMS

To investigate the role of vitamin D2 on the resolution of ST-segment elevation (STE) after a primary percutaneous coronary intervention (PCI), as serum levels of vitamin D have been associated with the severity of coronary artery disease.

METHODS AND RESULTS

All patients who underwent PCI for STEMI were screened for enrolment. Vitamin D2 levels were measured on admission along with other biochemical and haematologic assays. The electrocardiography (ECG) was recorded upon arrival and 60 min after the completion of PCI. The primary endpoint of the study was a ≥ 50% resolution of ST-segment amplitude (+STR) when compared to the initial ECG. A logistic regression multivariate analysis was performed to examine the association of STR with all confounding variables, including the admission levels of vitamin D. Receiver-operator characteristics analysis was used to determine the cut-off value of vitamin D that was predictive of STR. Although there was no difference in STR based on standard classification of vitamin D sufficiency, critically low levels of vitamin D (<7.5 ng/mL) were significantly associated with the absence of STR after PCI (AUC was 0.65 ± 0.07; p < 0.001). Critical vitamin D deficiency was a moderate predictor of STR in these patients, with a sensitivity of 86% and specificity of 54%.

CONCLUSION

We concluded that although levels below ten ng/mL were generally accepted as vitamin D deficiency, only critically low levels of this vitamin (<7.5 ng/dL) reliably predicted the resolution of ST-segment after a primary PCI for patients with STEMI.

Endothelial Function Assessment by Flow-Mediated Dilation Method: A Valuable Tool in the Evaluation of the Cardiovascular System

Cardiovascular diseases (CVDs) in the course of atherosclerosis are one of the most critical public health problems in the world. Endothelial cells synthesize numerous biologically active substances involved in regulating the functions of the cardiovascular system. Endothelial dysfunction is an essential element in the pathogenesis of atherosclerosis. Thus, the assessment of endothelial function in people without overt CVD allows for a more accurate estimate of the risk of developing CVD and cardiovascular events. The assessment of endothelial function is primarily used in scientific research, and to a lesser extent in clinical practice. Among the tools for assessing endothelial function, we can distinguish biochemical and physical methods, while physical methods can be divided into invasive and non-invasive methods. Flow-mediated dilation (FMD) is based on the ultrasound assessment of changes in the diameter of the brachial artery as a result of increased blood flow. FMD is a non-invasive, safe, and repeatable test, but it must be performed by qualified and experienced medical staff. The purpose of this paper is to present the literature review results on the assessment of endothelial function using the FMD method, including its methodology, applications in clinical practice and research, limitations, and future perspectives.

The Role of Vitamin D3 as an Independent Predicting Marker for One-Year Mortality in Patients with Acute Heart Failure

Background: Deficiency in vitamin D3 and its metabolites has been linked to dismal outcomes in patients with chronic diseases, including cardiovascular disease and heart failure (HF). It remains unclear if a vitamin D3 status is a prognostic feature in patients with acute decompensated HF. Methods: We assessed serum levels of 25-OH-vitamin D3 and 1,25-(OH)2-vitamin D3 in 139 patients with acute HF who had been admitted to the intermediate care unit of a maximum care hospital. The follow-up period was one year. After exclusion of patients with sampling errors and those who were lost to follow-up, 118 patients remained in the final study cohort. Outcome estimates by 25-OH-vitamin D3 and 1,25-(OH)2-vitamin D3 levels were compared to the Seattle Heart Failure (SHF) Model. Results: More than two-thirds (79.7%) of the patients showed inadequate 25-OH-vitamin D3 levels (i.e., <30 ng/mL) upon admission. Low levels of 1,25-(OH)2-vitamin D3 (i.e., <19.9 pg/mL) were observed in 16.1% of patients. Of the 118 HF patients, 22 (19%) died during the following 12 months. There were no differences in vitamin D3 levels between patients who died and those who survived, neither in 25-OH-vitamin D3 (23.37 ± 19.14 ng/mL vs. 19.11 ± 12.25 ng/mL; p = 0.19) nor in 1,25-(OH)2-vitamin D3 levels (31.10 ± 19.75 ng/mL vs. 38.25 ± 15.73 ng/mL; p = 0.02); therefore, vitamin D3 levels alone did not predict one-year survival (AUC [25-OH-vitamin D3] 0.50; 95% CI 0.34−0.65; AUC [1,25-(OH)2-vitamin D3] 0.62; 95% CI 0.48−0.76). Moreover, whilst the SHF model exhibited acceptable discriminatory ability for predicting one-year mortality (AUC 0.79; 95% CI 0.66−0.91), adding vitamin D levels on admission to the SHF score did not improve its discriminatory value. Conclusion: Our data do not support the use of vitamin D3 screening in patients admitted with acute decompensated HF to aid prognostication.

Vitamin D as therapeutic modulator in cerebrovascular diseases: a mechanistic perspectives

Vitamin D deficiency has been linked to several major chronic diseases, such as cardiovascular and neurodegenerative diseases, diabetes, and cancer, linked to oxidative stress, inflammation, and aging. Vitamin D deficiency appears to be particularly harmful to the cardiovascular system, as it can cause endothelial dysfunctioning and vascular abnormalities through the modulation of various downstream mechanisms. As a result, new research indicates that therapeutic approaches targeting vitamin D inadequacies or its significant downstream effects, such as impaired autophagy, abnormal pro-inflammatory and pro-oxidant reactions, may delay the onset and severity of major cerebrovascular disorders such as stroke and neurologic malformations. Vitamin D modulates the various molecular pathways, i.e., Nitric Oxide, PI3K-Akt Pathway, cAMP pathway, NF-kB Pathway, Sirtuin 1, Nrf2, FOXO, in cerebrovascular disorder. The current review shows evidence for vitamin D's mitigating or slowing the progression of these cerebrovascular disorders, which are significant causes of disability and death worldwide.

Vitamin D Level in Patients with Consecutive Acute Coronary Syndrome Is Not Correlated with the Parameters of Platelet Activity

Coronary artery disease continues to be the leading cause of death in developed countries. Elevated mean platelet volume (MPV) is associated with an increased incidence of myocardial infarction (MI) and MI-related mortality. Vitamin D concentrations affect the level and function of platelets, which are the crucial mediator of atherothrombosis and plaque rupture. The main aim of this study was to examine the relationship of serum 25-hydroxyvitamin D (25(OH)D) levels with the platelet activity in patients with a history of an acute coronary syndrome (ACS). This prospective study recruited 268 patients with a history of MI who underwent coronary angiography due to the suspicion of another ACS. Serum 25(OH)D concentration was determined by electrochemiluminescence. Platelet activity was assessed using the MPV and platelet-large cell ratio (P-LCR) parameters. There was no significant difference in MPV and P-LCR values between patients diagnosed with subsequent MI and patients with chronic coronary syndrome (CCS). A significantly lower level of 25(OH)D was demonstrated in patients who had another MI compared to those with CCS (p < 0.05). No significant correlation of 25(OH)D concentrations with platelet activity parameters values was found. The subgroup of patients with consecutive MI was characterized by significantly lower serum vitamin D levels, but this was not related to the analyzed parameters of platelet activity.

Vitamin supplementation as a potential adjunctive therapeutic approach for COVID-19: biological and clinical plausibility

The recent pandemic, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the causative agent of Coronavirus Disease 2019 (COVID-19) has introduced itself into the human population in the 21st century after the coronavirus diseases SARS-CoV and Middle East respiratory syndrome (MERS-CoV). Major investigations are underway worldwide in the search for pharmaceutical interventions for COVID-19 and many agents are administered in off-label routes. Several cases are under study to check or restrict clinical manifestations of COVID-19. According to the fact that the efficacy of some micro-nutrients like vitamins is proven to treat or prevent infectious diseases because of their antimicrobial and immunomodulatory activity, the potential role of vitamins in the COVID-19 treatment or prevention must be considered.

Vitamin D, Its Role in Recovery after Muscular Damage Following Exercise

Aside from its role in bone metabolism, vitamin D is a key immunomodulatory micronutrient. The active form of vitamin D (1,25(OH)D) seems to modulate the innate immune system through different mechanisms. The vitamin is involved in the differentiation of monocytes into macrophages, increasing the phagocytic and chemotactic functions of these cells. At the same time, vitamin D enables efferocytosis and prevents immunopathology. In addition, vitamin D is involved in other processes related to immune function, such as inflammation. Regarding muscle tissue, vitamin D plays an active role in muscle inflammatory response, protein synthesis, and regulation of skeletal muscle function. Two mechanisms have been proposed: A direct role of 1,25(OH)D binding to vitamin D receptors (VDRs) in muscle cells and the modulation of calcium transport in the sarcoplasmic reticulum. This second mechanism needs additional investigation. In conclusion, vitamin D seems to be effective in cases of deficiency and/or if there is a great muscular commitment, such as in high intensity exercises.

The effect of vitamin D supplementation on flow-mediated dilatation, oxidized LDL and intracellular adhesion molecule 1 on type 2 diabetic patients with hypertension: A randomized, placebo-controlled, double-blind trial

AIMS

Current study aimed to evaluate the effect of vitamin D supplementation on flow-mediated dilatation (FMD), oxidized LDL (oxLDL) and intracellular adhesion molecule 1 (ICAM1) in type 2 diabetic patients with hypertension.

METHODS

In a double-blinded, placebo-controlled trial, 44 patients were randomly divided into vitamin D group (2000 IU/d, n = 23) and placebo group (control, n = 21) for 12 weeks. Vascular function with FMD, Serum 25-OH vitamin D, oxLDL and ICAM1 were assessed at the baseline and after the intervention. This clinical trial was registered at Iranian Registry of Clinical Trials (IRCT20191223045861N1).

RESULTS

In intervention group serum level of vitamin D increased from 32.42 ± 10.56 to 40.45 ± 12.94 (p < 0.001). In the vitamin D group, oxLDL and ICAM1 significantly decreased and FMD increased significantly in both groups (p < 0.001). The level of oxLDL (p = 0.017) and ICAM1 (p < 0.001) were significantly lower in the vitamin D group than the placebo group and FMD (p < 0.001) was significantly higher in the vitamin D group.

CONCLUSIONS

Vitamin D supplementation of 2000 IU/d for 12 weeks can improve endothelial function and decrease ICAM1 and oxLDL in type 2 diabetic patients with hypertension.

[Interest of vitamin D in COVID-19]

Vitamin D, which is increasingly in demand in pharmacies and increasingly prescribed, could be an asset in the treatment of Covid-19 by reducing mortality or the severity of the condition. Its potential immunomodulatory effect is currently being studied by numerous international teams of researchers.

The effect of PCOS status on atherosclerosis markers and cardiovascular disease risk factors in young women with vitamin D deficiency

OBJECTIVE

To investigate whether polycystic ovary syndrome (PCOS) had further deteriorating influence on endothelial function or cardiometabolic parameters in women with vitamin D deficiency during reproductive age.

STUDY DESIGN

The study group was composed of women with PCOS and vitamin D deficiency and insufficiency between the ages of 18 and 35 years. Age and body mass index (BMI)-matched women were chosen as controls. Serum 25(OH) Vit D levels below 20 ng/mL were considered as vitamin D deficiency. The cutoff level of vitamin D insufficiency was suggested at 30 ng/mL. Serum FSH, LH, estradiol, testosterone, DHEA-S, fasting glucose, total cholesterol, HDL, LDL, triglyceride levels were analyzed. Carotid artery intima-media thickness (CIMT) was measured, and the flow-mediated vasodilation (FMD) was calculated.

RESULTS

CIMT and FMD values in both vitamin D deficiency and insufficiency subgroups showed no significant difference between PCOS and non-PCOS groups. There was a weak negative correlation between BMI, waist/hip ratio, CRP, and 25(OH) Vitamin D.

CONCLUSION

PCOS is a heterogeneous disease with different combinations of the diagnostic components. Vitamin D is an important variable for a healthy cardiovascular system. We did not find any difference in early atherosclerotic markers and cardiometabolic features between PCOS and non-PCOS group with Vitamin D deficiency.

Understanding the Biological Activities of Vitamin D in Type 1 Neurofibromatosis: New Insights into Disease Pathogenesis and Therapeutic Design

Vitamin D is a fat-soluble steroid hormone playing a pivotal role in calcium and phosphate homeostasis as well as in bone health. Vitamin D levels are not exclusively dependent on food intake. Indeed, the endogenous production-occurring in the skin and dependent on sun exposure-contributes to the majority amount of vitamin D present in the body. Since vitamin D receptors (VDRs) are ubiquitous and drive the expression of hundreds of genes, the interest in vitamin D has tremendously grown and its role in different diseases has been extensively studied. Several investigations indicated that vitamin D action extends far beyond bone health and calcium metabolism, showing broad effects on a variety of critical illnesses, including cancer, infections, cardiovascular and autoimmune diseases. Epidemiological studies indicated that low circulating vitamin D levels inversely correlate with cutaneous manifestations and bone abnormalities, clinical hallmarks of neurofibromatosis type 1 (NF1). NF1 is an autosomal dominant tumour predisposition syndrome causing significant pain and morbidity, for which limited treatment options are available. In this context, vitamin D or its analogues have been used to treat both skin and bone lesions in NF1 patients, alone or combined with other therapeutic agents. Here we provide an overview of vitamin D, its characteristic nutritional properties relevant for health benefits and its role in NF1 disorder. We focus on preclinical and clinical studies that demonstrated the clinical correlation between vitamin D status and NF1 disease, thus providing important insights into disease pathogenesis and new opportunities for targeted therapy.

Vitamin D and Endothelial Function

Vitamin D is known to elicit a vasoprotective effect, while vitamin D deficiency is a risk factor for endothelial dysfunction (ED). ED is characterized by reduced bioavailability of a potent endothelium-dependent vasodilator, nitric oxide (NO), and is an early event in the development of atherosclerosis. In endothelial cells, vitamin D regulates NO synthesis by mediating the activity of the endothelial NO synthase (eNOS). Under pathogenic conditions, the oxidative stress caused by excessive production of reactive oxygen species (ROS) facilitates NO degradation and suppresses NO synthesis, consequently reducing NO bioavailability. Vitamin D, however, counteracts the activity of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase which produces ROS, and improves antioxidant capacity by enhancing the activity of antioxidative enzymes such as superoxide dismutase. In addition to ROS, proinflammatory mediators such as TNF-α and IL-6 are risk factors for ED, restraining NO and eNOS bioactivity and upregulating the expression of various atherosclerotic factors through the NF-κB pathway. These proinflammatory activities are inhibited by vitamin D by suppressing NF-κB signaling and production of proinflammatory cytokines. In this review, we discuss the diverse activities of vitamin D in regulating NO bioavailability and endothelial function.

Limited role for fibroblast growth factor 23 in assessing prognosis in heart failure patients: data from the TIME-CHF trial

AIM

Fibroblast growth factor 23 (FGF23) is an intensively studied biomarker at the crossroads of cardiovascular disease, heart failure (HF) and chronic kidney disease. Independent associations between increasing FGF23 levels and cardiovascular events were found in many, but not all studies. By analysing data from the TIME-CHF cohort, we sought to investigate the prognostic value of FGF23 in an elderly, multimorbid HF patient cohort. We determined differences between intact (iFGF23) and C-terminal FGF23 (cFGF23) regarding their prognostic value and their levels over time in different HF subgroups according to left ventricular ejection fraction (LVEF).

METHODS AND RESULTS

In this multicentre trial of 622 patients with symptomatic HF aged ≥60 years, we determined iFGF23 and cFGF23 at baseline, 3, 6 and 12-month follow-up. In unadjusted analyses, cFGF23 significantly predicted all HF-related outcomes at all time points. The predictive value of iFGF23 was less and not statistically significant at baseline. After multivariable adjustments, the association between both cFGF23 and iFGF23 and outcome lost statistical significance apart from cFGF23 at month 3. Overall, patients with preserved and mid-range LVEF had higher levels of iFGF23 and cFGF23 than those with reduced LVEF. Levels decreased significantly during the first 3 months in mid-range and reduced LVEF patients, but did not significantly change over time in those with preserved LVEF.

CONCLUSIONS

Fibroblast growth factor 23 is of limited value regarding risk prediction in this elderly HF population. Potentially heterogeneous roles of FGF23 in different LVEF groups deserve further investigation.

Five salmon dinners per week were not sufficient to prevent the reduction in serum vitamin D in autumn at 60° north latitude: a randomised trial

Low serum concentrations of several vitamins have been linked to increased risk of diseases including insulin resistance and type 2 diabetes (T2D). Fish is a good source of several vitamins, and the prevalence of T2D is low in populations with high fish intake. The aim of the present study was to investigate the effects of high fish intake on vitamins in serum from adults in autumn in South-Western Norway at 60° north latitude. In this randomised clinical trial, sixty-three healthy participants with overweight/obesity consumed 750 g/week of either cod (n22) or salmon (n22) as five weekly dinners or were instructed to continue their normal eating habits but avoid fish intake (Control group,n19) for 8 weeks. The estimated vitamin D intake was significantly increased in the Salmon group when compared with the Cod group (P= 6·3 × 10−4) and with the Control group (P= 3·5 × 10−6), with no differences between groups for estimated intake of vitamins A, B1, B2, B3, B6, B9, C and E. Serum 25-hydroxyvitamin D3concentration was decreased in all groups after 8 weeks; however, the reduction in the Salmon group was significantly smaller compared with the Cod group (P= 0·013) and the Control group (P= 0·0060). Cod and salmon intake did not affect serum concentrations of the other measured vitamins. The findings suggest that 750 g/week of salmon was not sufficient to prevent a decrease in serum 25-hydroxyvitamin D3in autumn in South-Western Norway in adults with overweight/obesity.

Gender Differences in Vitamin D Status in China

Background

Vitamin D insufficiency is widespread in China. Various factors influence vitamin D level in the body. The present study investigated vitamin D status of residents in Jinzhong city, China, and analyzed the influence of gender on vitamin D status.

Material/Methods

In this cross-sectional study, 302 participants (176 men and 126 women) were recruited. Anthropometric data (body circumferences and height, weight) were collected, and serum vitamin D concentration was tested.

Results

Inadequate levels of vitamin D were found in 69% of men and 75% of women. Women’s 25(OH)D level (38.40±12.37 nmol/l) was substantially lower than that of the men (43.49±14.78 nmol/l) (p<0.01). The young women group had the lowest vitamin D level, which was even significantly below that of the elderly women group. Multiple linear regression analysis showed gender was significantly associated with vitamin D status (p<0.01).

Conclusions

Vitamin D deficiency is common in residents of Jinzhong during the winter. Compared to men, women are more prone to have inadequate vitamin D levels.

Vitamin D supplementation has no effect on matrix metalloproteinases-2, -9, and tissue inhibitor matrix metalloproteinase-1 in subjects with metabolic syndrome: A pilot study

The present randomized, double-blind, placebo controlled study aimed to evaluate the effect of vitamin D supplementation on matrix metalloproteinases-2, -9 (MMP-2 and MMP-9) and tissue inhibitor of metalloproteinase-1 (TIMP-1) in subjects with metabolic syndrome. Forty-six eligible subjects were randomly assigned to either vitamin D or placebo groups for 16 weeks. The participants were asked to take 50,000 IU vitamin D or matching placebo every week. Metabolic and anthropometric indices, serum MMP-2, MMP-9, TIMP-1 and high-sensitivity C-reactive protein (hsCRP) were assessed before and after intervention. Moreover, dietary intake, sun exposure and physical activity were also determined. The trial was registered at http://www.irct.ir (No. IRCT201409033140N14). Participants were 40.20 ± 4.60 y and 45.50% males. Compared to the baseline values, MMP-9 and TIMP-1 concentrations were decreased after 16 weeks in the intervention group (p = 0.03 and p = 0.04, respectively). However, the changes of MMP-2, MMP-9, TIMP-1 and hsCRP in the intervention group were not significant compared to the placebo group (p > 0.05). Furthermore, the metabolic or anthropometric indices between two study groups remained unchanged (p > 0.05). The findings of the present study demonstrated no effect of vitamin D supplementation on MMP-2, MMP-9 and TIMP-1 concentrations in subjects with metabolic syndrome. However, there is a need for more longitudinal trials to investigate the role of vitamin D on atherosclerosis and cardiovascular diseases in subjects with metabolic syndrome.

Calcium and vitamin D supplement intake may increase arterial stiffness in systemic lupus erythematosus patients

OBJECTIVES

Low serum levels of 25-hydroxyvitamin D (25(OH)D) have been associated with a higher frequency of risk factors and cardiovascular disease. The aim of this study is to evaluate the association of 25(OH)D, cardiovascular risk factors, and subclinical atherosclerosis in systemic lupus erythematosus (SLE) patients.

METHOD

Forty-seven female SLE patients were studied. Data collected included demographics, SLE activity, disease damage, cardiovascular risk factors, and markers of subclinical atherosclerosis. Patient treatments and vitamin D and calcium supplementation (VitD-Ca) were recorded. Vitamin D deficiency was defined as serum 25(OH)D < 50 nmol/l measured by ultra-high-performance liquid chromatography. Atherosclerosis was assessed by measuring the carotid-femoral pulse wave velocity (PWV) by Doppler velocimetry and intima-media thickness (IMT) by B-mode ultrasound scanning.

RESULTS

61.7% of patients were vitamin D deficient with a mean level of 31.91 ± 10.21 nmol/l. Serum vitamin D concentration was significantly higher in the 23 patients taking VitD-Ca supplements than that in patients not supplemented (p = 0.004). No significant association was found between 25(OH)D serum levels and cardiovascular risk factors, disease activity, or different treatments for SLE. A significant positive correlation was found between 25(OH)D levels, PWV (p = 0.02), and IMT (p = 0.01); moreover, patients taking VitD-Ca supplements presented an increased arterial stiffness.

CONCLUSION

Patients with arterial stiffness showed higher levels of serum vitamin D and most of them were on VitD-Ca supplements. Although prospective studies with a larger number of patients and follow-up are needed, our findings suggest that VitD-Ca supplementation may have effects on SLE patients' arterial stiffness.

Crosstalk between advanced glycation end products and vitamin D: A compelling paradigm for the treatment of ovarian dysfunction in PCOS

Women with PCOS have elevated levels of the harmful advanced glycation end products (AGEs) and low serum levels of vitamin D. AGEs and their receptors may contribute to the pathogenesis of PCOS and its metabolic and reproductive consequences. On the other hand, vitamin D might improve PCOS phenotype and could alleviate the detrimental effects of AGEs. A literature review using PubMed was performed. Critical analysis was carried out for articles pertaining to: 1) the role of AGEs and their receptors in the pathophysiology of PCOS, in particular ovarian dysfunction, and 2) the action of vitamin D in attenuating the adverse effects of AGEs in women with PCOS at both the serum and the cellular levels. Data from in vitro experiments, animal models, and human studies provide compelling evidence that AGEs and their receptors may contribute to the pathogenesis of ovarian dysfunction in PCOS. The actions of AGEs in PCOS might be attenuated and/or reversed by the presence or supplementation of vitamin D. Once a mechanistic understanding of the relationship between AGEs and vitamin D is established, this knowledge might contribute to the subsequent development of new-targeted pharmacological therapies for improving ovarian health in women with PCOS.

Vitamin D deficiency and risk of cardiovascular diseases: a narrative review

Vitamin D, a fat-soluble prohormone, has wide-ranging roles in the regulation of many physiological processes through their interactions with the vitamin D receptors (VDR). It plays a major role in bones and calcium metabolism. Vitamin D deficiency is not uncommon and it has been associated with many health-related issues, including skeletal and non-skeletal complications. The association of low vitamin D and cardiovascular diseases and risk factors has been explored in both animal and human studies. However, studies and trials on the effect of vitamin D supplementation on cardiovascular risk factors and hypertension are conflicting with inconsistent results. Therefore, large, well-powered randomized controlled trials are warranted. If successful, supplementation with easy and low-cost vitamin D can impact our health positively. Here, we summarized the evidence for the association of vitamin D, cardiovascular diseases and risk factors, including coronary artery diseases, stroke, and hypertension, and mortality, with special consideration to resistant hypertension.

Effect of vitamin D on isoprenaline-induced myocardial infarction in rats: possible role of peroxisome proliferator-activated receptor-γ

Infarct-like lesion induced by isoprenaline is a well-known model to study myocardial infarction (MI). Vitamin D has been shown to have anti-inflammatory and antioxidant effects. Recent studies highlighted cross talk between vitamin D and peroxisome proliferator-activated receptor gamma (PPAR-γ). The present study was designed to investigate the effect of pretreatment with vitamin D on the isoprenaline-induced infarct-like lesion in rats and the role of PPAR-γ as a novel mechanism in vitamin-D-mediated cardioprotective effect. Markers chosen to assess cardiac damage included serum level of creatine kinase (CK), lactate dehydrogenase (LDH), tumor necrosis factor-alpha (TNF-α), and interleukin-6 (IL-6). Cardiac contents of malondialdehyde (MDA), superoxide dismutase (SOD), and glutathione peroxidase (GSH) were also assessed. Furthermore, ECG monitoring and measurement of injury extension were carried out. Isoprenaline increased the level of cardiac enzymes, as well as inflammatory and oxidative stress biomarkers. In addition, it produced ST-segment elevation. Pretreatment with vitamin D significantly improved previous parameters. The prior treatment with bisphenol A diglycidyl ether (BADGE), a PPAR-γ antagonist, significantly attenuated the protective effect of vitamin D. In conclusion, vitamin D can be demonstrated as a promising cardioprotective agent in MI and PPAR-γ significantly contributes toward vitamin-D-mediated protection.

Effect of Vitamin D Supplementation on Delayed Hyperphosphatemia in Pediatric Acute Lymphoblastic Leukemia Patients During Induction Chemotherapy

OBJECTIVES

Vitamin D plays a role in maintaining bone health and calcium metabolism, but recent studies cast doubt on vitamin D supplementation's benefits in survivors of acute lymphoblastic leukemia (ALL). Vitamin D supplementation could increase serum phosphate through increased intestinal absorption of phosphate and suppression of parathyroid hormone, which would lead to decreased renal phosphate excretion. Because of the potential for renal injury during induction chemotherapy for ALL, Vitamin D supplementation's potential for increasing hyperphosphatemia could outweigh its suggested but unproven benefits.

METHODS

To measure the interaction between vitamin D supplementation and phosphate during chemotherapy induction, a retrospective study was done. Demographic data; clinical information about the diagnosis; laboratory data regarding calcium, phosphate, and vitamin D concentrations; and medication histories were reviewed.

RESULTS

A retrospective study of 41 children with ALL showed no statistically significant difference in the final phosphate concentrations that were obtained (4.41 mg/dL vs. 4.53 mg/dL, p = 0.635) with regard to their vitamin D supplementation status. Longitudinal effects with vitamin D and phosphate showed a trend toward increasing phosphate concentrations in patients who received supplemental vitamin D (0.035 vs. 0.010 mg/dL per day; p = 0.102).

CONCLUSIONS

Vitamin D potentially poses a risk of hyperphosphatemia in children undergoing induction chemotherapy for ALL.

Cardiac involvement in patients with cirrhosis: a focus on clinical features and diagnosis

Cirrhotic heart has been traditionally considered protected from cardiovascular disease, even if a large amount of literature has recently shown that patients affected by chronic liver disease are exposed to cardiovascular events, as well. Since the first recognition of cardiac involvement in cirrhosis, all published studies explain that decompensated cirrhotic patients suffer from haemodynamic changes, currently known as hyperdynamic syndrome, which finally lead to cirrhotic cardiomyopathy. This is defined by the presence of a subclinical systolic dysfunction unmasked under stress conditions, impaired diastolic function and electrophysiological abnormalities, in the absence of any known cardiac disease. In this review, we will discuss the clinical and diagnostic features of this condition, the prevalence of associated comorbidities, echocardiographic, electrocardiographic and cardiac magnetic resonance hallmarks and the possible diagnostic role of serum biomarkers.

Vitamin D-rich marine Inuit diet and markers of inflammation - a population-based survey in Greenland

The traditional Inuit diet in Greenland consists mainly of fish and marine mammals, rich in vitamin D. Vitamin D has anti-inflammatory capacity but markers of inflammation have been found to be high in Inuit living on a marine diet. Yet, the effect of vitamin D on inflammation in Inuit remains unsettled. This led us to investigate the association between vitamin D and markers of inflammation in a population with a high intake of a marine diet. We studied 535 Inuit and non-Inuit living in West and East Greenland. Information concerning dietary habits was obtained by interview-based FFQ. Blood samples were drawn for analysis of 25-hydroxyvitamin D, high-sensitivity C-reactive protein (hsCRP) and chitinase-3-like protein 1(YKL-40). Participants were divided into three groups based on degree of intake of the traditional Inuit diet. The diet groups (Inuit diet/mixed diet/imported foods) were associated with vitamin D levels in serum (74·2, 69·8 and 52·9 nm; P < 0·001), hsCRP (1·6, 1·4 and 1·3 mg/l; P = 0·002) and YKL-40 (130, 95 and 61 ng/ml; P < 0·001), respectively. YKL-40 level decreased with rising vitamin D level in Inuit (Inuit diet P = 0·002; mixed diet P = 0·011). YKL-40 was lower in groups with higher vitamin D levels after adjusting for other factors known to influence inflammation (P < 0·001). This was not seen for hsCRP. In conclusion, vitamin D and markers of inflammation vary in parallel with the intake of the marine Inuit diet. Vitamin D levels were inversely associated with YKL-40 levels, but no association with hsCRP was found. The hypothesised anti-inflammatory effect of vitamin D was not supported. Other factors in the marine diet may be speculated to influence inflammation.

Effects of vitamin D supplementation as an adjuvant therapy in coronary artery disease patients

OBJECTIVES

Low vitamin D status has been shown to be associated with coronary artery disease. We planned to research the effects of vitamin D3 supplementation on the severity of coronary artery disease.

DESIGN

We investigated the effect of 0.5 μg vitamin D3 per day in a randomized, placebo-controlled, double-blind study in 90 stable coronary artery disease patients residing in Beijing. Coronary angiography was performed before and after 6 months of treatment that took place between January and June. 25-Hydroxyvitamin D was measured by chemiluminescence assay. Coronary artery disease severity was assessed by using the SYNTAX scores.

RESULTS

In vitamin D supplementation group, there was a significant increase in mean 25-hydroxyvitamin D levels from baseline (19.9 ± 9.8 ng/ml) to 6 months (35.8 ± 12.1 ng/ml; p < 0.001). At 6 months, the primary end point, a difference in the fall of SYNTAX score between the groups was -2.5 (95% CI -5.1 to -0.5; p < 0.001) under intention to treat analysis. Compared with the control group, patients treated with vitamin D3 also had greater decreases in high sensitivity C-reactive protein and renin-angiotensin system activity (p < 0.05).

CONCLUSIONS

Vitamin D supplementation has beneficial effects on coronary artery disease; it can be an adjuvant therapy for patients with coronary artery disease.

Circulating 25-hydroxyvitamin D and risk of lung cancer: a dose-response meta-analysis

BACKGROUND

Mounting experimental evidence supports a protective effect of high 25-hydroxyvitamin D (25[OH]D), a good indicator of vitamin D status, on risk of various cancers including lung cancer. However, prospective observational studies examining the 25(OH)D-lung cancer association reported inconsistent findings. A dose-response meta-analysis was carried out to elucidate the subject.

METHODS

Potentially eligible studies were identified by searching PubMed and EMBASE databases, and by carefully reviewing the bibliographies of retrieved publications. The summary relative risks (RRs) with 95% confidence intervals (CIs) were calculated using the random-effects model.

RESULTS

Thirteen reports from ten prospective studies were included, totaling 2,227 lung cancer events. Results of the meta-analysis showed a significant 5% (RR 0.95, 95% CI 0.91-0.99) reduction in the risk of lung cancer for each 10 nmol/L increment in 25(OH)D concentrations. This inverse association was not significantly modified by area, study duration, sex, methods for 25(OH)D measurement, baseline 25(OH)D levels, or quality score of included studies. There was evidence of a nonlinear relationship between 25(OH)D and risk of lung cancer (p-nonlinearity = 0.02), with the greatest reductions in risk observed at 25(OH)D of nearly 53 nmol/L, and remained protective until approximately 90 nmol/L. Further increases showed no significant association with cancer risk, but scanty data were included in the analyses of high-level 25(OH)D. There was no evidence of publication bias.

CONCLUSION

This dose-response meta-analysis of prospective studies suggests that 25(OH)D may be associated with reduced risk of lung cancer, in particular among subjects with vitamin D deficiencies.

Total 25-hydroxyvitamin D concentration as a predictor for all-cause death and cardiovascular event risk among ethnic Chinese adults: a cohort study in a Taiwan community

BACKGROUND

Evidence of an inverse association between serum 25-hydoroxyvitamin D [25(OH)D] and the risk of all-cause death and cardiovascular disease from prospective studies is inconsistent. We tested the relationship between 25(OH)D and the risk among adult ethnic Chinese in Taiwan.

METHODS

We conducted a community-based cohort study of 1816 participants (age 60.2±10.2 yrs, 45.0% women) in the Chin-Shan Community Cardiovascular Cohort Study who were free of cardiovascular diseases at baseline and provided 25(OH)D measurements.

RESULTS

During a median 9.6 (interquartile range, 8.8- 10.5) years' follow-up period, totally 263 cases developed cardiovascular death events and 559 participants were documented to death from any cause. As 25(OH)D concentration increased, the incidence rates of cardiovascular events and all-cause death decreased progressively. 25(OH)D was inversely associated with all-cause death: the adjusted hazard ratio was 0.49 (95% confidence interval [CI], 0.25-0.97) for the third quartile and a significant J-shape relationship was found. The performance measures by integrated discriminative improvement showed significant improvement after adding 25(OH)D information (0.14%, 95% CI, 0.03-0.31, P=0.050, for all-cause death and 0.32%, 95% CI, 0.02-0.62, P=0.018 for cardiovascular events).

CONCLUSION

These findings suggested a modest inverse association between 25(OH)D and the risk of all-cause death among diabetic participants and a good predictive factor in the community. Further studies to investigate the mechanism of vitamin D role on health effect are warranted.

Hypovitaminosis D and organ damage in patients with arterial hypertension: a multicenter double blind randomised controlled trial of cholecalciferol supplementation (HYPODD) : study design, clinical procedures and treatment protocol

INTRODUCTION

At this time, good quality randomized clinical trials assessing the effects of vitamin D supplementation on cardiometabolic outcomes are lacking in the international literature.

AIM

To fill this gap, the Working Group on Vitamin D and Cardiorenal Disorders established jointly by the Italian Society of Hypertension (SIIA) and the Forum in Bone and Mineral Research conceived the HYPODD study (HYPOvitaminosis D and organ Damage).

METHODS

HYPODD is a no-profit multicenter 12-month parallel-group double-blind placebo controlled randomized trial aiming to assess the effects of cholecalciferol supplementation on blood pressure control, antihypertensive drugs consumption and progression of target organ damage in patients with essential hypertension and 25-hydroxyvitamin D serum level lower than 20 ng/ml (vitamin D deficiency). HYPODD is coordinated by the European Society Excellence Center of Hypertension of Federico II University, Naples, and involves 12 academic institutions in Italy (Ancona, Milan, Padua, Perugia, Rome, Siena, Trieste, Turin, Udine, Varese, and Verona).

RESULTS AND CONCLUSION

The HYPODD study has been registered at the Agenzia Italiana del Farmaco-Osservatorio sulla Sperimentazione Clinica del Farmaco (AIFA-OsSC) and EUDRACT sites (n° 2012-003514-14) and has been approved by the Ethical Committees of all the Centers involved in the study. The patients' recruitment is currently underway.

Serum 25-hydroxyvitamin D levels are associated with carotid atherosclerosis in normotensive and euglycemic Chinese postmenopausal women: the Shanghai Changfeng study

Background

The role of serum 25-hydroxyvitamin D (25 (OH) D) in atherogenesis is unclear. We investigated whether the 25 (OH) D is independently associated with the carotid intima–media thickness (CIMT) and carotid plaques in normotensive and euglycemic postmenopausal women.

Methods

A total of 671 normotensive and euglycemic postmenopausal women (mean age, 58.8 years) were enrolled from the Changfeng Study. A standard interview, anthropometrics measurements and laboratory analyses were performed for each participant. Bilateral CIMTs were measured using ultrasonography, and the presence of carotid plaques was assessed. The serum 25 (OH) D was measured using electrochemiluminescence immunoassay.

Results

Serum 25 (OH) D was 43.6 ± 18.2 nmol/L in the postmenopausal women. Compared with subjects with 25 (OH) D in the first, second and third quartiles, subjects with 25 (OH) D in the fourth quartile had decreased CIMT and prevalence of carotid plaque (0.684 ± 0.009 mm vs 0.719 ± 0.009 mm, 0.708 ± 0.009 mm and 0.709 ± 0.009 mm; 10.8% vs 19.0%, 14.8% and 16.8%, respectively). After adjusting for conventional CVD risk factors, PTH, liver and renal function, postmenopausal women with 25 (OH) D in the fourth quartile still had lower CIMT than those in the first, second and third quartiles (p = 0.039) and the subjects in the fourth quartile had a 0.421-fold decreased risk of carotid plaques relative to those in the lowest quartile (95% confidence interval 0.209 to 0.848).

Conclusions

These results suggest serum 25 (OH) D is independently and inversely associated with carotid atherosclerosis in postmenopausal women with normal blood pressure and normal glucose tolerance.

Does sufficient evidence exist to support a causal association between vitamin D status and cardiovascular disease risk? An assessment using Hill's criteria for causality

Serum 25-hydroxyvitamin D (25(OH)D) levels have been found to be inversely associated with both prevalent and incident cardiovascular disease (CVD) risk factors; dyslipidemia, hypertension and diabetes mellitus. This review looks for evidence of a causal association between low 25(OH)D levels and increased CVD risk. We evaluated journal articles in light of Hill's criteria for causality in a biological system. The results of our assessment are as follows. Strength of association: many randomized controlled trials (RCTs), prospective and cross-sectional studies found statistically significant inverse associations between 25(OH)D levels and CVD risk factors. Consistency of observed association: most studies found statistically significant inverse associations between 25(OH)D levels and CVD risk factors in various populations, locations and circumstances. Temporality of association: many RCTs and prospective studies found statistically significant inverse associations between 25(OH)D levels and CVD risk factors. Biological gradient (dose-response curve): most studies assessing 25(OH)D levels and CVD risk found an inverse association exhibiting a linear biological gradient. Plausibility of biology: several plausible cellular-level causative mechanisms and biological pathways may lead from a low 25(OH)D level to increased risk for CVD with mediators, such as dyslipidemia, hypertension and diabetes mellitus. Experimental evidence: some well-designed RCTs found increased CVD risk factors with decreasing 25(OH)D levels. Analogy: the association between serum 25(OH)D levels and CVD risk is analogous to that between 25(OH)D levels and the risk of overall cancer, periodontal disease, multiple sclerosis and breast cancer.

CONCLUSION

all relevant Hill criteria for a causal association in a biological system are satisfied to indicate a low 25(OH)D level as a CVD risk factor.

Fibroblast growth factor 23 (FGF23) and mortality: the Ludwigshafen Risk and Cardiovascular Health Study

BACKGROUND

Fibroblast growth factor 23 (FGF23) is an important regulatory hormone in phosphate and vitamin D metabolism. Here, we investigated the associations of FGF23 with traditional cardiovascular risk factors and with bone metabolism parameters as well as the impact of FGF23 upon long-term mortality in a large cohort of patients referred for coronary angiography.

METHODS

We examined whether c-term FGF23 concentrations at baseline were associated with cardiovascular and total mortality in 2974 patients from the Ludwigshafen Risk and Cardiovascular Health Study (LURIC). We investigated if these associations were independent from established cardiovascular risk factors as well as from other mineral regulating factors and bone biomarkers such as calcium, parathyroid hormone (PTH), alkaline phosphatase (AP), vitamin D, and serum phosphate.

RESULTS

Mean age of participants was 63 ± 10 years; median c-term FGF23 serum levels were 54 (40-78) RU/ml. During a median follow-up of 9.9 years, 884 deaths (30%) occurred, 545 (18%) of which were cardiovascular. FGF23 significantly and inversely correlated with eGFR. AP, phosphate, and PTH increased in parallel with quartiles of FGF23. Age- and sex-adjusted hazard ratios (HRs) in the fourth quartile compared to the first quartile of FGF23 were 2.54 (95%CI, 2.09-3.09; p < 0.001) for all cause and 2.56 (95% CI, 1.99-3.28; p < 0.001) for cardiovascular mortality. These associations remained significant after additional adjustments for cardiovascular risk factors and bone biomarkers (calcium, PTH, AP, vitamin D, and phosphate): Adjusted HRs were 1.38 (95%CI, 1.26-1.52; p < 0.001) for all-cause and 1.35 (95%CI, 1.20-1.52; p < 0.001) for cardiovascular mortality for each increase by one standard deviation of c-term FGF23.

CONCLUSIONS

In patients undergoing coronary angiography baseline c-term FGF23 levels predict the risk for all-cause and cardiovascular mortality over 9.9 years of follow-up. These associations were independent of established cardiovascular risk factors and serum phosphate.

Egg consumption and carotid atherosclerosis in the Northern Manhattan study

BACKGROUND

The evidence supporting recommendations to limit intake of cholesterol rich foods is inconclusive. We aimed to examine the association between egg consumption and carotid atherosclerosis phenotypes, and the association with clinical vascular events in a prospective, urban, multi-ethnic population.

METHODS AND RESULTS

The Northern Manhattan Study is a population based cohort to determine stroke incidence, risk factors and prognosis. A sub-cohort of 1429 NOMAS participants with both carotid ultrasounds and comprehensive dietary information was evaluated (mean ± SD age of participants 65.80 ± 8.80, 40% male, 18% white, 20% black, 60% Hispanic). The association between egg consumption and carotid intima media thickness (cIMT) was assessed with linear regression. Logistic and quantile regression was used to examine the association between egg consumption and carotid plaque presence, thickness, and area. The relation between egg consumption and clinical vascular events (N = 2669) was examined with Cox models. The mean total cIMT was 0.91 ± 0.08 mm and 58% had carotid plaque present. Increasing egg consumption was inversely associated with cIMT, plaque presence, thickness, and area, in models adjusted for demographics, vascular risk factors and diet. For every additional egg consumed per week, the risk of plaque decreased by 11% (95% CI 3%-18%). No association was detected between egg consumption and risk of clinical vascular outcomes, over a mean follow up of 11 years and after adjustment for covariates.

CONCLUSIONS

Frequency of egg consumption in the low to moderate range was inversely related to several markers of carotid atherosclerosis. No association with clinical vascular events, including stroke, was detected. Our findings do not support current vascular health guidelines suggesting the extreme limitation or avoidance of egg consumption due to its cholesterol content.

The role of the intraplaque vitamin d system in atherogenesis

Vitamin D has been shown to play critical activities in several physiological pathways not involving the calcium/phosphorus homeostasis. The ubiquitous distribution of the vitamin D receptor that is expressed in a variety of human and mouse tissues has strongly supported research on these "nonclassical" activities of vitamin D. On the other hand, the recent discovery of the expression also for vitamin D-related enzymes (such as 25-hydroxyvitamin D-1 α -hydroxylase and the catabolic enzyme 1,25-dihydroxyvitamin D-24-hydroxylase) in several tissues suggested that the vitamin D system is more complex than previously shown and it may act within tissues through autocrine and paracrine pathways. This updated model of vitamin D axis within peripheral tissues has been particularly investigated in atherosclerotic pathophysiology. This review aims at updating the role of the local vitamin D within atherosclerotic plaques, providing an overview of both intracellular mechanisms and cell-to-cell interactions. In addition, clinical findings about the potential causal relationship between vitamin D deficiency and atherogenesis will be analysed and discussed.

Effects of vitamin d on blood pressure and endothelial function

Vitamin D deficiency is prevalent, primarily due to limited sun exposure, which may be observed in urban areas, or as a result of modern lifestyles. Common myths about vitamin D persist, including that it is mostly obtained from the diet and is only essential for bone and mineral homeostasis. Nonetheless, advances in biomedical science suggest that vitamin D is a hormone that is integral to numerous physiologic functions in most cells and tissues. Therefore, abnormal vitamin D levels may contribute to health disturbances. A number of recent reports on potential associations between vitamin D deficiency and cardiovascular disease have highlighted its role in this system. A focus over the previous decade has been to better understand the mechanisms behind vitamin D regulation and the pathophysiology associated with suboptimal vitamin D levels. Vitamin D deficiency is highly associated with the incidence of cardiovascular diseases, even when considering other well-known risk factors. In this process, the renin-angiotensin system is disrupted, and hypertension and endothelial dysfunction contribute to the risk of cardiovascular disease. Likewise, clinical outcomes upon the normalization of vitamin D levels have been investigated in different patient populations. It makes sense that vitamin D supplementation to improve vitamin D status among vitamin D-deficient individuals could be useful without requiring a sudden lifestyle change. This manuscript provides a brief overview of vitamin D metabolism and the vitamin D receptor. It also summarizes the current clinical research relating to vitamin D supplementation and its effects on hypertension and endothelial dysfunction in cardiovascular medicine.

Mutation in CYP27A1 identified in family with coronary artery disease

Coronary artery disease (CAD) is a leading cause of death worldwide. Myocardial infarction is the most severe outcome of CAD. Despite extensive efforts, the genetics of CAD is poorly understood. We aimed to identify the genetic cause of CAD in a pedigree with several affected individuals. Exome sequencing led to identification of a mutation in CYP27A1 that causes p.Arg225His in the encoded protein sterol 27-hydroxylase as the likely cause of CAD in the pedigree. The enzyme is multifunctional, and several of its functions including its functions in vitamin D metabolism and reverse cholesterol transport (RCT) are relevant to the CAD phenotype. Measurements of vitamin D levels suggested that the mutation does not affect CAD by affecting this parameter. We suggest that the mutation may cause CAD by affecting RCT. Screening of all coding regions of the CYP27A1 in 100 additional patients led to finding four variations (p.Arg14Gly, p.Arg26Lys, p.Ala27Arg, and p.Val86Met) in seven patients that may contribute to their CAD status. CYP27A1 is the known causative gene of cerebrotendinous xanthomatosis, a disorder which is sometimes accompanied by early onset atherosclerosis. This and the observation of potentially harmful variations in unrelated CAD patients provide additional evidence for the suggested causative role of the p.Arg225His mutation in CAD.

Plasma vitamin D-binding protein and risk of heart failure in male physicians

Previous studies have suggested that vitamin D deficiency might contribute to the pathogenesis of heart failure (HF); however, limited data are available on the association of vitamin D-binding protein (VDBP)--a major transport protein for vitamin D--and the development of HF. Thus, we investigated whether plasma VDBP is inversely associated with HF risk. Using a prospective nested case-control design, we selected 464 cases and 464 matched controls from the Physicians' Health Study for the present analyses. VDBP was determined using an enzyme-linked immunoassay. Self-reported HF was obtained through annual follow-up questionnaires and validated in a subsample by a review of the medical records. We used conditional logistic regression analyses to compute the adjusted odds ratios. The mean age was 58.6 years, and the median VDBP was 307.8 μg/ml (interquartile range 265.2 to 354.6). Plasma VDBP was not associated with HF in our study. Across the consecutive quintiles of VDBP, the odds ratio was 1.0 (95% confidence interval [CI] reference), 1.05 (95% CI 0.66 to 1.65), 1.28 (95% CI 0.80 to 2.06), 1.07 (95% CI 0.65 to 1.75), and 1.28 (95% CI 0.76 to 2.15); p for linear trend = 0.41, after adjustment for matching factors, body mass index, diabetes, atrial fibrillation, hypertension, and high-sensitivity C-reactive protein. In conclusion, our data have shown no significant association between the plasma levels of VDBP and HF risk in apparently healthy male physicians.

Plasma 25-hydroxyvitamin D and its genetic determinants in relation to incident myocardial infarction and stroke in the European prospective investigation into cancer and nutrition (EPIC)-Germany study

Circulating 25-hydroxyvitamin D (25(OH)D) has been associated with cardiovascular disease (CVD) risk in observational studies. Also, SNPs to explain variation in 25(OH)D have been identified by genome-wide association studies. Detection of direct associations between SNPs that significantly affect 25(OH)D and CVD risk would indicate a causal role of vitamin D, as reverse causation could be excluded and confounding could be better controlled. Thus, a combined analysis of candidate SNPs in relation to circulating 25(OH)D and CVD risk was carried out. A case-cohort study within the EPIC-Germany study was conducted comprising a randomly drawn subcohort of 2,132 subjects (57.9% women, mean age: 50.6 years) and incident cases of myocardial infarction (n=559) and stroke (n=471) that occurred during a mean follow-up duration of 7.6 years. 25(OH)D concentrations were measured by LC-MS/MS in baseline plasma samples. Additionally, eight candidate SNPs were assayed. Associations between 25(OH)D, SNPs and the risks of myocardial infarction and stroke were assessed by multivariable regression analyses. Mean 25(OH)D level was 47.2 nmol/L in the subcohort. Four SNPs were associated with 25(OH)D (p<0.05). In subjects with 25(OH)D levels <25 nmol/L, the risks of CVD as composite endpoint (Hazard Ratio: 1.53, 95% confidence interval: 1.12–2.09), myocardial infarction, and stroke were significantly increased compared to subjects with levels ≥50 nmol/L, while no significant linear associations were observed. A SNP score was not related to the risks of total CVD (Hazard Ratio: 1.0, 95% confidence interval: 0.71–1.42), myocardial infarction, or stroke. The same was true concerning single SNPs. Given the lack of association between SNPs and the risks of stroke and myocardial infarction, the present findings do not point to a major causal role of vitamin D in the development of these diseases. However, a detection of modest associations between genetic markers and CVD risk in larger consortia cannot be ruled out.

Egg consumption and risk of coronary heart disease and stroke: dose-response meta-analysis of prospective cohort studies

OBJECTIVE

To investigate and quantify the potential dose-response association between egg consumption and risk of coronary heart disease and stroke.

DESIGN

Dose-response meta-analysis of prospective cohort studies.

DATA SOURCES

PubMed and Embase prior to June 2012 and references of relevant original papers and review articles.

ELIGIBILITY CRITERIA FOR SELECTING STUDIES

Prospective cohort studies with relative risks and 95% confidence intervals of coronary heart disease or stroke for three or more categories of egg consumption.

RESULTS

Eight articles with 17 reports (nine for coronary heart disease, eight for stroke) were eligible for inclusion in the meta-analysis (3,081,269 person years and 5847 incident cases for coronary heart disease, and 4,148,095 person years and 7579 incident cases for stroke). No evidence of a curve linear association was seen between egg consumption and risk of coronary heart disease or stroke (P=0.67 and P=0.27 for non-linearity, respectively). The summary relative risk of coronary heart disease for an increase of one egg consumed per day was 0.99 (95% confidence interval 0.85 to 1.15; P=0.88 for linear trend) without heterogeneity among studies (P=0.97, I(2)=0%). For stroke, the combined relative risk for an increase of one egg consumed per day was 0.91 (0.81 to 1.02; P=0.10 for linear trend) without heterogeneity among studies (P=0.46, I(2)=0%). In a subgroup analysis of diabetic populations, the relative risk of coronary heart disease comparing the highest with the lowest egg consumption was 1.54 (1.14 to 2.09; P=0.01). In addition, people with higher egg consumption had a 25% (0.57 to 0.99; P=0.04) lower risk of developing hemorrhagic stroke.

CONCLUSIONS

Higher consumption of eggs (up to one egg per day) is not associated with increased risk of coronary heart disease or stroke. The increased risk of coronary heart disease among diabetic patients and reduced risk of hemorrhagic stroke associated with higher egg consumption in subgroup analyses warrant further studies.