Serum 25-hydroxyvitamin D levels and all-cause and cardiovascular disease mortality among US adults with hypertension: the NHANES linked mortality study

Systemic lupus erythematosus and vitamin D deficiency are associated with shorter telomere length among African Americans: a case-control study

Systemic lupus erythematosus (SLE) is a chronic systemic autoimmune disease that disproportionately affects African American females. The causes of SLE are unknown but postulated to be a combination of genetic predisposition and environmental triggers. Vitamin D deficiency is one of the possible environmental triggers. In this study we evaluated relationships between vitamin D status, cellular aging (telomere length) and anti-telomere antibodies among African American Gullah women with SLE. The study population included African American female SLE patients and unaffected controls from the Sea Island region of South Carolina. Serum 25-hydroxyvitamin D levels were measured using a nonchromatographic radioimmunoassay. Telomere length was measured in genomic DNA of peripheral blood mononuclear cells (PBMCs) by monochrome multiplex quantitative PCR. Anti-telomere antibody levels were measured by enzyme-linked immunosorbent assay (ELISA). Patients with SLE had significantly shorter telomeres and higher anti-telomere antibody titers compared to age- and gender-matched unaffected controls. There was a positive correlation between anti-telomere antibody levels and disease activity among patients and a significant correlation of shorter telomeres with lower 25-hydroxyvitamin D levels in both patients and controls. In follow-up examination of a subset of the patients, the patients who remained vitamin D deficient tended to have shorter telomeres than those patients whose 25-hydroxyvitamin D levels were repleted. Increasing 25-hydroxyvitamin D levels in African American patients with SLE may be beneficial in maintaining telomere length and preventing cellular aging. Moreover, anti-telomere antibody levels may be a promising biomarker of SLE status and disease activity.

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.

Vitamin D intake and dietary sources in a representative sample of Spanish adults

BACKGROUND

Vitamin D plays an essential role in bone mineralisation and its deficiency is associated with several chronic diseases. Some studies have reported a deficient status of vitamin D in Spanish and European population. The present study aimed to assess vitamin D intake, dietary sources of this nutrient and its adequacy with respect to the dietary reference intakes (DRI) in a representative sample of Spanish adults.

METHODS

Four hundred and eighteen adults (aged 18-60 years) from 15 Spanish provinces were studied. They constituted a representative sample of the Spanish adult population. Energy and nutrient intake were determined using a 24-h dietary recall questionnaire for two consecutive days. Vitamin D intake was compared with the DRI for this vitamin.

RESULTS

Mean (SD) vitamin D intake was 3.5 (4.0) μg day(-1) (69.5% of the DRI). Of the participants studied, 81.6% had vitamin D intakes below the DRI and 68.7% had intakes below 67% of the DRI. Of the vitamin D, 91.4% came from food sources and 8.6% came from dietary supplements. The main food sources of vitamin D were fish, eggs, dairy products, cereals, oils and meat. In addition, those subjects who met the DRI for vitamin D had a higher consumption of fish, vegetables and fruits and a lower consumption of meats than those subjects who did not meet the DRI.

CONCLUSIONS

Vitamin D intake was inadequate in the sample of the adult Spanish population. Therefore, an increase in the consumption of oily fish, as well as fortified dairy products and cereals, might help to improve vitamin D intake.

Should hypertensive patients take vitamin D?

The prevalence of both hypertension and vitamin D deficiency is high. The discovery of the vitamin D receptor and its possible effects on components of the cardiovascular system influencing blood pressure, such as the renin angiotensin system, the heart, the kidney and the blood vessels, has generated the hope that vitamin D therapy could be a new target for the treatment for hypertensive patients. Cross-sectional studies have clearly shown an association between low levels of vitamin D and hypertension. This association is not as clear in longitudinal studies. Finally, evidence from randomized controlled trials specifically designed to test the hypothesis of a blood pressure lowering effect of vitamin D is weak. Therefore, there is actually not enough evidence to recommend giving vitamin D to reduce blood pressure in hypertensive patients.

Potential benefits of vitamin D for patients with systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is a complex multi-system autoimmune disease. Vitamin D deficiency has been proposed as an environmental trigger of disease onset and as a contributor to increased SLE activity. SLE patients are prone to develop vitamin D deficiency because of photosensitivity leading to sun avoidance and other sun protective measures. The impact of vitamin D on immune function previously seen in vitro and in cross-sectional studies has now been shown in prospective human studies, strengthening the evidence that there is a connection between SLE and vitamin D status. This review describes the role of vitamin D on immune function, prevalence of vitamin D deficiency in patients with SLE, identify risk factors for deficiency, describe the consequences of deficiency in SLE patients, and review current vitamin D recommendations for patients with SLE.

Vitamin D and sepsis: An emerging relationship

Vitamin D insufficiency and sepsis are both highly prevalent worldwide problems and this article reviews the emerging science that is defining the intersections of these conditions. The importance of vitamin D’s role in skeletal health has long been understood but recent evidence is beginning to highlight its role in the functioning of other physiologic systems of the body. Basic science data reveal its integral role in local immune responses to pathogens and the systemic inflammatory pathways of sepsis. Furthermore, clinical scientists have found associations with respiratory infections, critical illness and sepsis but the causal relationship and its clinical impact have yet to be clearly defined. The article ends with speculations on the connections between racial disparities and seasonal differences in sepsis and vitamin D insufficiency.

Chronic kidney disease and vascular remodelling: molecular mechanisms and clinical implications

CKD (chronic kidney disease) is a severe and complex disease with a very high prevalence of CV (cardiovascular) complications. CKD patients are exposed to haemodynamic disturbances in addition to severe metabolic abnormalities that lead to a specific form of arterial remodelling, which contributes to the development of CV disease. Arterial calcification is a major event in the arterial remodelling process and is strongly linked to mineral metabolism abnormalities associated with CKD. Arterial remodelling is not limited to arterial calcification and modifications in arterial wall composition are also observed. Activation of the RAS (renin-angiotensin system), ET-1 (endothelin-1), endothelial dysfunction, oxidative stress and ADMA (asymmetric ω-NG,NG-dimethylarginine), as well as the anti-aging molecule Klotho, are implicated in this process. The present review details the mechanisms involved in arterial calcification and arterial remodelling associated with CKD, and provides the clinical consequences of large and small artery stiffness and remodelling in CKD patients.

Vitamin D in sepsis: from basic science to clinical impact

The growing basic and clinical investigations into the extraskeletal effects of vitamin D have revealed roles in the functioning of the immune system, generating interesting questions about this nutrient's connections to sepsis. This article briefly reviews the current science of the function of vitamin D in the immune system as well as the emerging clinical literature regarding its associations with respiratory infections, sepsis, and critical illness. Finally, we offer views on the potential future directions for research in the field by outlining potential relevant scenarios and outcomes.

Is vitamin D status relevant to metabolic syndrome?

Review of the evidence on hypovitaminosis D as a risk factor for metabolic syndrome and its sequelae, T2DM and CVD, suggests long-term vitamin D repletion could reduce these risks. There is mechanistic evidence for protective effects for MetS and the balance of evidence, (cross-sectional and prospective), supports this postulate. Much of the data so far available from randomized controlled trials is weakened by inadequate power, low vitamin D dosages, starting supplementation too late in life or after MetS disorders have developed or, most importantly, by non-inclusion of many recognizable confounders. On balance, therefore, maintenance of US 2010 recommended intakes for bone protection has the potential to prove protective for MetS. Supplementation has been shown to increase survival in patients with cardiac disorders; whether higher doses would provide useful protection for apparently healthy people in the general population awaits the outcomes of ongoing randomized-controlled trials that, it is hoped, will prove or disprove causality for hypovitaminosis D in MetS and its long-term ill-effects.