Critique of the U-shaped serum 25-hydroxyvitamin D level-disease response relation

Histopathological role of vitamin D deficiency in recurrent/chronic tonsillitis pathogenesis: Vascular epithelial growth factor-mediated angiogenesis in tonsil

Objectives

Our aim in this study is to reveal the role of vitamin D deficiency in the pathogenesis of recurrent/chronic tonsillitis and to determine the expression of vascular epithelial growth factor (VEGF).

Material and Methods

This study was conducted between September and February. Thirty‐two patients between the ages of 3 and 35 (mean age 9.71) with recurrent episodes of chronic tonsillitis were selected. Patients were divided into four groups according to their 25OHD levels. Patients with 25OHD levels 0–10 ng/ml were determined as Group 1, 11–20 ng/ml Group 2, 21–30 ng/ml Group 3, and 31–50 ng/ml control Group 4. Routine histological tissue sampling was performed for histopathological evaluation of the tonsillar tissues under light microscope (LM). Five micron sections were taken from the paraffin blocks and stained with Hematoxylin Eosin (HE) and Trichrome Masson (TCM). VEGF expression was examined immunohistochemically for each group.

Results

Our analysis showed VEGF expression in all study groups (32 tonsillar tissues). Group 1 and Group 2 histopathological scores were significantly higher than the other groups (p < .001). There were significant differences in VEGF expressions between the four groups (p < .001). 25OHD levels of the patients in Groups 1 and 2 with strong VEGF expression were significantly lower than the other groups (p < .001).

Conclusions

In conclusion, this study showed an increased angiogenesis in tonsil and an increase in VEGF expression of the tonsillar surface epithelium when blood serum 25OHD levels <20 ng/ml.

Micronutrients in Atopic Dermatitis: A Systematic Review

Objective: The pathophysiology of atopic dermatitis (AD) involves a complex interplay between immune system dysfunction, genetics, and environmental factors. It is well known that nutritional status is essential to a proper functioning immune system, leading to a highly debated question regarding the role of dietary factors in the pathogenesis of AD. Food allergies and elimination diets have been broadly studied in atopy; however, less consideration has been given to how vitamins, minerals, and other micronutrients influence the risk for AD and severity of symptoms. This systematic review discusses evidence on how various micronutrients, including vitamins (C, E, and D) and trace minerals (zinc, selenium, iron, copper, magnesium, and strontium) are associated with AD, and how supplementation influence disease severity. Design: A systematic search was conducted to identify the role that oral micronutrients have on AD. The authors reviewed 49 studies herein. Results: While there are weak associations between vitamins C or E and AD, there is sufficient evidence to suggest that vitamin D supplementation provides benefit in AD patients. Deficiency of selenium and zinc may exacerbate AD. Current reports are not sufficient to confidently discern the role of other vitamins and trace minerals on AD. Conclusions: Though oral micronutrients may play a role in AD, the current literature is limited, and there is a need for more comprehensive randomized controlled trials (RCTs) to truly decipher the role between oral micronutrients and AD.

Vitamin D and cardiovascular diseases: Causality

Vitamin D regulates blood pressure, cardiac functions, and endothelial and smooth muscle cell functions, thus, playing an important role in cardiovascular health. Observational studies report associations between vitamin D deficiency with hypertension and cardiovascular-related deaths. Peer-reviewed papers were examined in several research databases as per the guidelines of the Preferred Reporting Items for Systematic Reviews, using key words that address the relationship between vitamin D and cardiovascular disease. Correlations and interpretations were made considering the risks-benefits, broader evidence, and implications. This review analyzed current knowledge regarding the effects of vitamin D on the cardiovascular system. 1,25(OH)₂D and related epigenetic modifications subdue cellular inflammation, improve overall endothelial functions, reduce age-related systolic hypertension and vascular rigidity, and attenuate the actions of the renin-angiotensin-aldosterone system. Most observational and ecological studies support 25(OH)vitamin D having protective effects on the cardiovascular system. However, the association of vitamin D deficiency with cardiovascular diseases is based primarily on observational and ecological studies and thus, is a matter of controversy. Adequately powered, randomized controlled clinical trial data are not available to confirm these associations. Thus, to test the hypothesis that correction of vitamin D deficiency protects the cardiovascular system, well-designed, statistically powered, longer-term clinical trials are needed in persons with vitamin D deficiency. Nevertheless, the available data support that adequate vitamin D supplementation and/or sensible sunlight exposure to achieve optimal vitamin D status are important in the prevention of cardiovascular disease and other chronic diseases.

Vitamin D supplementation guidelines

Research carried out during the past two-decades extended the understanding of actions of vitamin D, from regulating calcium and phosphate absorption and bone metabolism to many pleiotropic actions in organs and tissues in the body. Most observational and ecological studies report association of higher serum 25-hydroxyvitamin D [25(OH)D] concentrations with improved outcomes for several chronic, communicable and non-communicable diseases. Consequently, numerous agencies and scientific organizations have developed recommendations for vitamin D supplementation and guidance on optimal serum 25(OH)D concentrations. The bone-centric guidelines recommend a target 25(OH)D concentration of 20ng/mL (50nmol/L), and age-dependent daily vitamin D doses of 400-800IU. The guidelines focused on pleiotropic effects of vitamin D recommend a target 25(OH)D concentration of 30ng/mL (75nmol/L), and age-, body weight-, disease-status, and ethnicity dependent vitamin D doses ranging between 400 and 2000IU/day. The wise and balanced choice of the recommendations to follow depends on one's individual health outcome concerns, age, body weight, latitude of residence, dietary and cultural habits, making the regional or nationwide guidelines more applicable in clinical practice. While natural sources of vitamin D can raise 25(OH)D concentrations, relative to dietary preferences and latitude of residence, in the context of general population, these sources are regarded ineffective to maintain the year-round 25(OH)D concentrations in the range of 30-50ng/mL (75-125nmol/L). Vitamin D self-administration related adverse effects, such as hypercalcemia and hypercalciuria are rare, and usually result from taking extremely high doses of vitamin D for a prolonged time.

Vitamin D supplementation as a potential cause of U-shaped associations between vitamin D levels and negative health outcomes: a decision tree analysis for risk of frailty

Background

A recent controversy in vitamin D research is a “U-shaped association”, with elevated disease risks at both high and low 25-hydroxyvitamin D (25 (OH) D) levels.

Methods

This is a cross-sectional study of 238 male nursing home veterans in Hawaii. Classification and regression tree (CART) analysis identified groups based on 25 (OH) D and vitamin D supplementation for frailty risk. Characteristics were examined and compared across the groups using logistic regression and receiver operating characteristic (ROC) curve analyses.

Results

CART analysis identified three distinct groups: vitamin D supplement users (n = 86), non-users with low vitamin D (n = 55), and non-users with high vitamin D (n = 97). Supplement users were the most frail, but had high mean 25 (OH) D of 26.6 ng/mL, which was compatible with 27.1 ng/mL in non-users with high vitamin D, while mean 25 (OH) D of non-users with low vitamin D was 11.7 ng/mL. Supplement users and non-users with low vitamin D were significantly more likely to be frail (odds ratio (OR) = 9.90, 95% CI = 2.18–44.86, p = 0.003; OR = 4.28, 95% CI = 1.44–12.68, p = 0.009, respectively), compared with non-users with low vitamin D. ROC curve analysis showed the three groups significantly predicted frailty (area under the curve = 0.73), with sensitivity of 64.4% and specificity of 76.7%, while 25 (OH) D did not predict frailty.

Conclusions

In these nursing home veterans, vitamin D supplement users were the most frail but with high 25 (OH) D. This can potentially be a cause of U-shaped associations between vitamin D levels and negative health outcomes.

Electronic supplementary material

The online version of this article (doi: 10.1186/s12877-017-0631-0) contains supplementary material, which is available to authorized users.

Plasma 25-hydroxyvitamin D levels, vitamin D intake, and pancreatic cancer risk or mortality: a meta-analysis

BACKGROUND

The associations between vitamin D status, including plasma 25-hydroxyvitamin D [25(OH)D] levels and vitamin D intake, and pancreatic cancer risk and mortality are inconsistent. The aims of this study are to evaluate the antitumor and therapeutic effects of vitamin D status for pancreatic cancer patients.

METHODS

A literature search for relevant studies was conducted using PubMed and Embase databases. Risk ratio (RR), hazard ratio (HR), and 95% confidence interval (CI) were used as the effect measures. All statistical analyses were performed using Stata software 12.0.

RESULTS

Our results indicated that high plasma 25(OH)D levels were inversely associated with pancreatic cancer mortality without significant heterogeneity (HR=0.81, 95% CI=0.68-0.96). However, high plasma 25(OH)D levels could not reduce pancreatic cancer risk (RR=1.02, 95% CI=0.66-1.57). Moreover, vitamin D intake was also not associated with pancreatic cancer risk (RR=1.11, 95% CI=0.67-1.86).

CONCLUSIONS

Our results indicate that high plasma 25(OH)D levels were significantly associated with improved survival in pancreatic cancer patients. However, there were no significant associations between vitamin D intake or plasma 25(OH)D levels and pancreatic cancer risk.

Low vitamin D level and impact on severity and recurrence of Clostridium difficile infections

BACKGROUND

Clostridium difficile infection (CDI) has recently markedly increased, incurring greater health care-associated costs and hospitalizations especially in vitamin D deficient patients. Accordingly, the aim of this study was to evaluate the relationship between low vitamin D levels and the severity and recurrence of CDI.

METHODS

A retrospective case-control study evaluated patients hospitalized between 2007 and 2013 with CDI and a positive C. difficile toxin assay. Severe complicated CDI was defined based on (1) laboratory or radiological criteria correlated clinically and (2) sepsis requiring intensive care unit admission. Recurrent CDI (RCDI) was defined as a new episode of diarrhea occurring within 90 days of resolution of the initial episode for at least 10 days after discontinuing therapy and confirmed by positive stool C. difficile toxin assay or polymerase chain reaction. Patients were divided into 4 groups based on vitamin D level (ng/mL): severely deficient (<10), insufficient (10-19.9), predeficient (20-29.9), and control group (≥30).

RESULTS

Two hundred seventy-one patients were diagnosed with CDI, of which 48 had RCDI distributed as 5 (12.5%), 15 (16.1%), 10 (15.6%), and 13 (17.5%) patients in each of the aforementioned groups, respectively (P=0.55). Severe complicated CDI was identified in 7 (17.5%), 17 (18.2%), 9 (14%), and 3 (4%) patients, respectively (P=0.04). Thirty-day mortality was 1 of 40, 1 of 93, 2 of 64, and 2 of 74 patients, respectively (P=0.43).

CONCLUSIONS

Normal vitamin D level has a protective effect against severe CDI, and low vitamin D is associated with greater severity of CDI but not with an increased risk of RCDI or 30-day mortality.

Association Between Serum 25-Hydroxy Vitamin D Levels and Blood Pressure Among Adolescents in Two Resource-Limited Settings in Peru

INTRODUCTION

Serum 25-hydroxyvitamin D (25OHD) deficiency (<50 nmol/l or 20 ng/ml) has been associated with increased blood pressure (BP) in observational studies. A paucity of data on this relationship is available in Latin American or child populations. This study investigates the association between 25OHD levels and BP in adolescents at risk for vitamin D deficiency in 2 Peruvian settings.

METHODS

In a population-based study of 1,441 Peruvian adolescents aged 13-15 years, 1,074 (75%) provided a serum blood sample for 25OHD analysis and BP measurements. Relationships between 25OHD and BP metrics were assessed using multiple linear regressions, adjusted for anthropometrics and sociodemographic factors.

RESULTS

25OHD deficiency was associated with an elevated diastolic BP (DBP) (1.09 mm Hg increase, 95% confidence interval: 0.04 to 2.14; P = 0.04) compared to nondeficient adolescents. Systolic BP (SBP) trended to increase with vitamin D deficiency (1.30 mm Hg increase, 95% confidence interval: -0.13 to 2.72; P = 0.08). Mean arterial pressure (MAP) was also greater in adolescents with 25OHD (1.16 mm Hg increase, 95% confidence interval: 0.10 to 2.22; P = 0.03). SBP was found to demonstrate a U-shaped relationship with 25OHD, while DBP and MAP demonstrated inverse J-shaped relationships with serum 25OHD status. The association between 25OHD deficiency and BP was not different across study sites (all P ≥ 0.19).

DISCUSSION

Adolescents deficient in 25OHD demonstrated increased DBP and MAP and a trend toward increased SBP, when compared to nondeficient subjects. 25OHD deficiency early in life was associated with elevated BP metrics, which may predispose risk of hypertension later in adulthood.

The Endocrinology of Ageing: A Mini-Review

Significant advances in health and social wellbeing have led to linear gains in life expectancy and an accompanying increase in the burden imposed by age-related morbidities. Complex alterations in hormonal networks which regulate homeostasis and survival may underlie this poor adaptation to later life, as exemplified by an increased fracture risk amongst post-menopausal women. Beyond overt under- or overactivity of hormonal axes, changes in the concentrations of regulatory hormones may also impact on health and disease. Subclinical hyperthyroidism, a disorder characterised by normal thyroxine levels in the presence of decreased thyroid-stimulating hormone, is, for instance, independently associated with an increased risk of atrial fibrillation amongst elderly populations. Both the menopause and subclinical thyroid disease demonstrate the difficulty in reversing endocrine changes in later life, with minimal impact from thyroxine therapy in subclinical hypothyroidism and multiple reports of harm resulting from hormone replacement therapy in peri- and post-menopausal women. Given these findings, strategies to locally regulate hormone bioavailability by altering pre-receptor metabolism may offer greater therapeutic potential in the fight against age-related disease. This review aims to provide an overview of the ageing endocrine system and its potential impact on health and disease in the elderly. It will postulate that strategies to coordinate pre-receptor hormone metabolism and a greater understanding of putative hormonal longevity pathways may offer key new drug targets in the fight against ageing, and will argue against applying the conventional endocrine maxim of 'block and replace' to hormonal changes seen during ageing.

The trials and tribulations of vitamin D: time for the 'sunshine' vitamin to come in out of the cold - or just more broken promises?

We are presently faced with the competing notions of modern life being a 'state of vitamin D depletion', implying a widespread need to supplement with vitamin D, or, the opposite view, which is that the present evidence can only support at best selective targeted vitamin D intervention. This is important as there is evidence that over the last 40-50 years there were downwards global trends in serum 25(OH)D concentrations, while individual consumption of vitamin D as supplements rose. For this reason and many others, a large population-based interventional study, the VITAL trial, was designed to try to establish the health value of vitamin D supplementation. VITAL is a huge primary prevention trial looking at the effects of vitamin D repletion in preventing cancer and cardiovascular disease in a fundamentally healthy population. This may seem an unusual approach given that what we mostly know about vitamin D is that is has some effects on the skeleton. This review looks to explore current knowledge about vitamin D in health and disease, and at how this is now undergoing significant reappraisal and revision. We will carefully critique the VITAL study design to see if it will allow for the construction of the detailed portfolio of clinical evidence so urgently needed to allow us better to understand role of vitamin D supplementation in health and disease.

Vitamin D and multiple sclerosis: where do we go from here?

This article briefly introduces the basics of multiple sclerosis' (MS) clinical hallmarks and pathophysiology. Vitamin D is presented, including its metabolism and effects on the immune system. The epidemiological observations linking vitamin D to MS range from a half century old findings of latitude gradients and migrational risk patterns to modern, nested, case-control biobank studies. These observations show an association without doubt although causation has yet to be proven. Vitamin D as a treatment for MS is an emerging concept and both current and anticipated data will be covered. Lastly, we discuss future challenges, ideas on how to move from association to causation, and the prospect of primary prevention of this disabling disease.

The potential therapeutic benefits of vitamin D in the treatment of estrogen receptor positive breast cancer

Calcitriol (1,25-dihydroxyvitamin D(3)), the hormonally active form of vitamin D, inhibits the growth of many malignant cells including breast cancer (BCa) cells. The mechanisms of calcitriol anticancer actions include cell cycle arrest, stimulation of apoptosis and inhibition of invasion, metastasis and angiogenesis. In addition we have discovered new pathways of calcitriol action that are especially relevant in inhibiting the growth of estrogen receptor positive (ER+) BCa cells. Calcitriol suppresses COX-2 expression and increases that of 15-PGDH thereby reducing the levels of inflammatory prostaglandins (PGs). Our in vitro and in vivo studies show that calcitriol decreases the expression of aromatase, the enzyme that catalyzes estrogen synthesis selectively in BCa cells and in the mammary adipose tissue surrounding BCa, by a direct repression of aromatase transcription via promoter II as well as an indirect effect due to the reduction in the levels of PGs, which are major stimulator of aromatase transcription through promoter II. Calcitriol down-regulates the expression of ERα and thereby attenuates estrogen signaling in BCa cells including the proliferative stimulus provided by estrogens. Thus the inhibition of estrogen synthesis and signaling by calcitriol and its anti-inflammatory actions will play an important role in inhibiting ER+BCa. We hypothesize that dietary vitamin D would exhibit similar anticancer activity due to the presence of the enzyme 25-hydroxyvitamin D-1α-hydroxylase (CYP27B1) in breast cells ensuring conversion of circulating 25-hydroxyvitamin D to calcitriol locally within the breast micro-environment where it can act in a paracrine manner to inhibit BCa growth. Cell culture and in vivo data in mice strongly suggest that calcitriol and dietary vitamin D would play a beneficial role in the prevention and/or treatment of ER+BCa in women.

Colonic vitamin D metabolism: implications for the pathogenesis of inflammatory bowel disease and colorectal cancer

In epidemiological studies serum levels below 30 nM of 25-OHD(3), the precursor of the active vitamin D metabolite 1,25-(OH)(2)D(3), were consistently associated with incidence of colorectal cancer. The active vitamin D metabolite possesses antimitotic, prodifferentiating and proapoptotic capacity in vivo and in vitro. The intestinal autocrine/paracrine vitamin D system, which is the main source of local 1,25-(OH)(2)D(3) plays a critical role in maintaining both mucosal immunity and normal growth of epithelial cells. It has been hypothesized that the VDR-mediated signaling antagonizing TNF-α and IL-6 receptor-activated pro-inflammatory and proliferative intracellular pathways, may prevent development of IBD and colitis-associated colorectal cancer. Conversely, any situation that impairs the efficiency of the 1,25-(OH)(2)D(3)/VDR signaling system at the level of the gut mucosa, e.g. vitamin D insufficiency, may increase risk for the development of IBD and colorectal cancer. Therefore, not only adequate serum levels of the precursor 25-OHD(3) are essential, but also optimal expression of the 1α-hydroxylating enzyme CYP27B1. The 1,25-(OH)(2)D(3) catabolizing hydroxylase CYP24A1 is increasingly expressed during colon cancer progression, indicating that colonocytes are released from normal growth control by the steroid hormone. Securing adequate levels of calcitriol by inhibition of catabolism and support of 1α-hydroxylation by calcium, phytoestrogens and folate could be a valid approach to control, at least in part, IBD and CRC pathogenesis.

An estimate of the global reduction in mortality rates through doubling vitamin D levels

BACKGROUND/OBJECTIVES

The goal of this work is to estimate the reduction in mortality rates for six geopolitical regions of the world under the assumption that serum 25-hydroxyvitamin D (25(OH)D) levels increase from 54 to 110 nmol/l.

SUBJECTS/METHODS

This study is based on interpretation of the journal literature relating to the effects of solar ultraviolet-B (UVB) and vitamin D in reducing the risk of disease and estimates of the serum 25(OH)D level-disease risk relations for cancer, cardiovascular disease (CVD) and respiratory infections. The vitamin D-sensitive diseases that account for more than half of global mortality rates are CVD, cancer, respiratory infections, respiratory diseases, tuberculosis and diabetes mellitus. Additional vitamin D-sensitive diseases and conditions that account for 2 to 3% of global mortality rates are Alzheimer's disease, falls, meningitis, Parkinson's disease, maternal sepsis, maternal hypertension (pre-eclampsia) and multiple sclerosis. Increasing serum 25(OH)D levels from 54 to 110 nmol/l would reduce the vitamin D-sensitive disease mortality rate by an estimated 20%.

RESULTS

The reduction in all-cause mortality rates range from 7.6% for African females to 17.3% for European females. Reductions for males average 0.6% lower than for females. The estimated increase in life expectancy is 2 years for all six regions.

CONCLUSIONS

Increasing serum 25(OH)D levels is the most cost-effective way to reduce global mortality rates, as the cost of vitamin D is very low and there are few adverse effects from oral intake and/or frequent moderate UVB irradiance with sufficient body surface area exposed.

Association between atherosclerosis and osteoporosis, the role of vitamin D

The latest data support the correlation of atherosclerosis and osteoporosis, indicating the parallel progression of two tissue destruction processes with increased fatal and non-fatal coronary events, as well as higher fracture risk. Vitamin D inadequacy associated with low bone mineral density increases fall and fracture risk, leads to secondary hyperparathyroidism, calcifies coronary arteries and significantly increases cardiovascular disease. Randomized clinical trial evidence related to extraskeletal vitamin D outcomes was limited and generally uninformative. A recent recommendation on vitamin D dietary requirements for bone health is 600 IU/d for ages 1-70 years and 800 IU/d for 71 years and older, corresponding to a serum 25-hydroxyvitamin D level of at least 20 ng/ml (50 nmol/l). Further large randomized controlled trials are needed to reassess laboratory ranges for 25-hydroxyvitamin D in both diseases, in order to avoid under- and over-treatment problems, and completely clarify the relationship between atherosclerosis and osteoporosis.

Role of vitamin d in the prevention of pancreatic cancer

Pancreatic cancer is a malignancy of poor prognosis which is mostly diagnosed at advanced stages. Current treatment modalities are very limited creating great interest for novel preventive and therapeutic options. Vitamin D seems to have a protective effect against pancreatic cancer by participating in numerous proapoptotic, antiangiogenic, anti-inflammatory, prodifferentiating, and immunomodulating mechanisms. 25-hydroxyvitamin D [25(OH)D] serum concentrations are currently the best indicator of vitamin D status. There are three main sources of vitamin D: sun exposure, diet,and dietary supplements. Sun exposure has been associated with lower incidence of pancreatic cancer in ecological studies. Increased vitamin D levels seem to protect against pancreatic cancer, but caution is needed as excessive dietary intake may have opposite results. Future studies will verify the role of vitamin D in the prevention and therapy of pancreatic cancer and will lead to guidelines on adequate sun exposure and vitamin D dietary intake.

Relation between prediagnostic serum 25-hydroxyvitamin D level and incidence of breast, colorectal, and other cancers

The evidence is increasing that higher serum 25-hydroxyvitamin D [25(OH)D] levels reduce the risk of many types of cancer. Ecological and observational studies yield the strongest evidence, with support from studies of mechanisms. A key question is identifying the relation between serum 25(OH)D level and cancer incidence. Meta-analyses of such studies is a reasonable approach to determine the serum 25(OH)D level-cancer incidence relation. This paper reports new meta-analyses for breast and colorectal cancers. Currently, the journal literature offers seven prospective breast cancer and ten prospective colorectal cancer studies that can be used. The data for these studies graphed and compared. Data from some of the studies were multiplied by factors to bring all the studies into reasonable agreement with a tentative dose-response relation. The data were fit with a variety of functions; the best fits were nonlinear functions that tended to asymptotically reach a lower odds ratio at higher serum 25(OH)D levels. These analyses estimated that the 50% reduction in incidence occurs for a value of 78 nmol/L compared with the value at 24 nmol/L for breast cancer, and a value of 60 nmol/L compared with the value at 15 nmol/L for colorectal cancer. Although these results are reasonable, some concern exists that a single serum 25(OH)D level, measured years prior to diagnosis of cancer, does not adequately represent the serum levels for the entire period before diagnosis. Future prospective studies should include more serum 25(OH)D level measurements during the study course.