The impact of living in rural and urban areas: vitamin D and medical costs in veterans

Relationship Between Glycated Hemoglobin (HbA1c) and Vitamin D Levels in Type 2 Diabetes Patients: A Retrospective Cross-Sectional Study

BACKGROUND

Significant links between low serum levels of vitamin D3 and insufficient glycemic control in patients with type 2 diabetes mellitus (T2DM) have been reported previously in the literature. However, there is no exciting evidence on the association between glycated hemoglobin (HbA1c) and vitamin D levels in T2DM individuals in our nation (Yemen). This study aimed to investigate the relationship between HbA1c and vitamin D levels in T2DM patients in a resource-limited setting.

METHOD

A retrospective cross-sectional study was conducted at the Al-Raffa Center, Ibb, Yemen between June 2018 and September 2023 including 396 patients diagnosed with T2DM. The patient characteristics, comorbidities, HbA1c, and vitamin D levels were gathered from patients' medical profiles. Linear regression analysis was used to find the factors associated with vitamin D deficiency (serum 25(OH)D levels < 20 ng/mL) among T2DM patients. Subsequently, the correlation between HbA1c and vitamin D levels was examined using receiver operating characteristic (ROC) curve analysis.

RESULTS

The mean age was 44.6 ±14.6 years and most of them (n= 227, 57.3%) were female and from a rural area (n= 229, 57.8%). Comorbidities were hypertension, dyslipidemia disease, and cardiovascular disease in 176 (44.4%), 63 (15.9%), and 88 (22.2%) cases, respectively. The mean HbA1c was 8.1 ±2.5%. The mean vitamin D level was 26.9 ±16.5 ng/mL and low vitamin D was present in 260 (65.7%) (vitamin D deficiency in 160 (40.4%) and vitamin D insufficiency in 100 (25.3%) cases). In regression analysis, obesity (>30 kg/m2) (odds ratio (OR): 299.49; 95% confidence interval (CI): 72.66 - 1234.42, p <0.0001), higher HbA1c levels (OR: 1.61; 95% CI: 1.26 - 2.05, p =0.0001), and urban residence (OR: 23.98; 95% CI: 5.62 - 102.42, p <0.0001) were associated with vitamin D deficiency. There was a negative correlation between the vitamin D level and HbA1c which was statistically significant (correlation coefficient r: -0.5452; 95% CI: -0.6109 to -0.4720, p <0.0001). Using the ROC analysis, the serum vitamin D value of ≤18.42 ng/ml was the best cut-off point to predict hyperglycemia (area under the curve: 0.633, 95% CI: 0.672 to 0.770, sensitivity: 52%, specificity: 84.71 %, Yoden's index: 0.3671, p <0.001). Based on this cut-off, 39.4% of individuals (37.5% in the normoglycemic group and 90.9% in the hyperglycemic group) were vitamin D deficient.

CONCLUSION

In this study, low vitamin D was common among T2DM patients, especially those with poor glycemic control. We observed a link between HbA1c levels, urban residency, and BMI with vitamin D deficiency in T2DM patients. The association was distinguished by low vitamin D levels and elevated HbA1c. Additionally, we found that the serum vitamin D value of ≤18.42 ng/ml was the best cut-off point to predict hyperglycemia in T2DM patients with moderate agreement. To manage their disease, patients with T2DM should take their medications as prescribed and live a healthy lifestyle. This will increase their overall health, especially their vitamin D levels.

Healthcare Costs and Healthcare Utilization Outcomes of Vitamin D3 Supplementation at 5000 IU Daily during a 10.9 Month Observation Period within a Pragmatic Randomized Clinical Trial

Vitamin D insufficiency has been linked to multiple conditions including bone disease, respiratory disease, cardiovascular disease, diabetes, and cancer. Observational studies indicate lower healthcare costs and healthcare utilization with sufficient vitamin D levels. The secondary aims of our previously published pragmatic clinical trial of vitamin D3 supplementation were comparisons of healthcare costs and healthcare utilization. Comparisons were made between the vitamin D3 at 5000 IU supplementation group and a non-supplemented control group. Costs of care between the groups differed but were not statistically significant. Vitamin D3 supplementation reduced healthcare utilization in four major categories: hospitalizations for any reason (rate difference: -0.19 per 1000 person-days, 95%-CI: -0.21 to -0.17 per 1000 person-days, p < 0.0001); ICU admissions for any reason (rate difference: -0.06 per 1000 person-days, 95%-CI: -0.08 to -0.04 per 1000 person-days, p < 0.0001); emergency room visits for any reason (rate difference: -0.26 per 1000 person-days, 95%-CI: -0.46 to -0.05 per 1000 person-days, p = 0.0131; and hospitalizations due to COVID-19 (rate difference: -8.47 × 10-3 per 1000 person-days, 95%-CI: -0.02 to -1.05 × 10-3 per 1000 person-days, p = 0.0253). Appropriately powered studies of longer duration are recommended for replication of these utilization findings and analysis of cost differences.

A Scoping Review of Vitamin D for Nonskeletal Health: A Framework for Evidence-Based Clinical Practice

BACKGROUND

Low serum 25-hydroxy-vitamin D [25(OH)D] levels are prevalent worldwide. Although the benefits of vitamin D supplementation have focused on skeletal disorders (eg, rickets, osteomalacia, osteoporosis), emerging evidence for nonskeletal health merits further discussion.

PURPOSE

The purpose of this review was to critically examine the vitamin D supplementation literature pertaining to nonskeletal health to help guide clinicians.

METHODS

A scoping review that included observational studies and randomized clinical trials (RCTs) was performed. Evidence from meta-analyses and individual RCTs are discussed, and controversies and future directions are considered.

FINDINGS

25(OH)D deficiency is a ubiquitous condition associated with multiple nonskeletal diseases, including cardiometabolic (heart disease, diabetes, and kidney disease), immune (HIV/AIDS and cancer), lung (from traditional chronic disorders to coronavirus disease 2019), and gut diseases. Vitamin D deficiency also affects health across the life span (children, pregnant, and elderly), mental illness, and reproduction in both men and women. In contrast, vitamin D supplementation does not necessarily improve major medical outcomes, even when low 25(OH)D levels are treated. Screening for 25(OH)D status remains an important practice, primarily for high-risk patients (eg, elderly, women with osteoporosis, people with low exposure to sunlight). It is reasonable to supplement with vitamin D to treat 25(OH)D deficiency, such that if beneficial nonskeletal health occurs, this may be considered as a coadjutant instead of the central tenet of the disease. Furthermore, optimizing dosing regimens is an important clinical consideration.

IMPLICATIONS

Although 25(OH)D deficiency is prevalent in nonskeletal diseases, there is no uniform evidence that vitamin D supplementation improves major medical outcomes, even when low 25(OH)D levels are corrected. Findings from RCTs warrant caution due to possible selection bias. Overall, vitamin D supplementation must be guided by circulating levels as a reasonable medical practice to correct 25(OH)D deficiency.

The associations between short-term exposure to ambient particulate matter and hospitalizations for osteoporotic fracture in Hangzhou: a time-stratified case-crossover study

Our results suggested that short-term exposure to particulate matter (PM) might increase the risks of hospitalizations for osteoporotic fractures. Government should protect its citizens by putting in place policies to reduce unhealthy emissions and air pollution.

INTRODUCTION

Osteoporotic fractures are accompanied by high rates of disability and mortality. PM has been linked with many health outcomes. However, few studies focus on the association of short-term exposure to ambient PM and osteoporotic fractures.

METHODS

Data on daily mean air pollution, meteorological factors, and hospitalizations for osteoporotic fractures were collected from Hangzhou, China, 2020-2021. A time-stratified case-crossover design with extended Cox proportional hazards regression was applied to assess the associations between PM and osteoporotic fractures.

RESULTS

Short-term exposure to PM significantly increased the risks of hospitalizations for osteoporotic fractures at cumulative lag days. Per 10 μg/m3 increased in PM2.5 (PM with an aerodynamic diameter ≤ 2.5 μm), PMC (PM with an aerodynamic diameter between 2.5 μm and 10 μm), and PM10 (PM with an aerodynamic diameter ≤ 10 μm) were associated with 5.65% (95% confidence intervals (CIs): 1.29, 10.19), 3.19% (0.11, 6.36), and 2.45% (0.57, 4.37) increase in hospitalizations for osteoporotic fractures, respectively. Significant PM-osteoporotic fracture associations were only observed in females and people aged over 65 years old. For the season, the estimates of PM on hospitalizations for osteoporotic fractures were 6.30% (95% CIs: 1.62, 11.20) in the cold season vs. 2.16% (95% CIs: - 4.62, 9.42) in the warm season for per 10 μg/m3 increase of PM2.5, and 0.99 (95% CIs: - 2.69, 4.80) vs. 6.72% (95% CIs: 0.68, 13.13) for PMC.

CONCLUSIONS

Our study showed PM was positively linked with the risk of osteoporotic fractures. Females and people aged over 65 years old were more susceptible to PM. The adverse impacts of PM2.5 in the cold season and PMC in the warm season were worthy of special attention.

Emerging Disparities in Prevention and Survival Outcomes for Patients with Head and Neck Cancer and Recommendations for Health Equity

Purpose of Review

The aim of this review is to describe less known and emerging disparities found in the prevention and survival outcomes for patients with head and neck cancer (HNC) that are likely to play an increasingly important role in HNC outcomes and health inequities.

Recent Findings

The following factors contribute to HNC incidence and outcomes: (1) the effect of rurality on prevention and treatment of HNC, (2) dietary behavior and nutritional factors influencing the development of and survival from HNC, and (3) barriers and benefits of telehealth for patients with HNC.

Summary

Rurality, nutrition and diet, and telehealth usage and access are significant contributors to the existing health disparities associated with HNC. Population and culturally specific interventions are urgently needed as well as more research to further define the issues and develop appropriate population and individual level solutions.

Assessment of sunlight exposure across industries and occupations using blood vitamin D as a biomarker

Objective

Exposure to ultraviolet (UV) radiation from sunlight induces the production of essential vitamin D, whereas overexposure to sunlight leads to skin cancer. Sunlight exposure has been measured using questionnaires, dosimeters, and vitamin D levels. Several studies have measured vitamin D in the working population; however, these studies were limited to certain occupations such as farmers and construction workers. In the present study, we evaluated sunlight exposure using blood vitamin D as an exposure surrogate across industries and occupations.

Methods

The Korea National Health and Nutrition Examination Survey (KNHANES) is a nationwide study representing the Korean population. We analyzed data from KNHANES between 2008 and 2009. We examined the association between vitamin D levels and pertinent personal, seasonal, residential, and occupational factors. Furthermore, we developed a multiple regression model with factors other than occupational factors (industry and occupation) and obtained residual values. We computed the third quartile (Q3) of the residuals and then calculated the fractions exceeding the Q3 level for each combination of industry and occupation.

Results

Age, sex, body mass index, year, season, latitude, living area, living in an apartment, industry, and occupation were significantly associated with vitamin D levels. Based on the exceeding fraction, the armed forces showed the highest exceeding fraction level of 0.71.

Conclusions

Our results present the high exposure groups to sunlight across industries and occupations. Our results may provide a source for prioritizing occupational groups with a high risk of adverse health effects from sunlight exposure.

The association between vitamin D levels and metabolic syndrome components among metropolitan adolescent population

OBJECTIVES

Vitamin D promotes both lipolysis and lipogenesis, and some pediatric studies showed inconsistent associations between vitamin D and metabolic syndrome (MetS). This cross-sectional study aimed to examine the association between vitamin D levels and MetS components among metropolitan adolescents.

METHODS

A total of 4,149 adolescents aged 10-18 years were recruited from 23 metropolises in China. The MetS conditions were assessed according to the International Diabetes Federation consensus definition, and the serum 25-hydroxy vitamin D (25(OH)D) concentrations were analyzed. The association between MetS components and serum 25(OH)D levels was analyzed by the logistic regression model. Restricted cubic spline was applied to the model nonlinear association.

RESULTS

Prevalence of vitamin D deficiency was 74.9%, and 41.2% of study participants had at least one MetS component. After adjustment, the significant trend for a lower waist-to-height ratio was not observed in study participants with higher serum 25(OH)D quartile (p=0.57), but a significant nonlinear association between abdominal obesity and serum 25(OH)D levels was found (p=0.04): the highest risk of abdominal obesity occurred at 14.1 ng/mL of serum 25(OH)D. The association of serum 25(OH)D was significantly inverse with MetS (OR: 0.95; 95% CI: 0.92-0.98), but not with raised triglycerides (OR: 0.99; 95% CI: 0.96-1.01), raised blood pressure (OR: 0.99; 95% CI: 0.97-1.01) and impaired fasting glycemia (OR: 1.03; 95% CI: 1.01-1.04).

CONCLUSIONS

The net effect of vitamin D on lipid metabolism may be concentration-dependent, and the actual effect of vitamin D on MetS process may be complex among metropolitan adolescents, though serum 25(OH)D is inversely associated with MetS.

Micronutrient Deficiency as a Confounder in Ascertaining the Role of Obesity in Severe COVID-19 Infection

Food insecurity in the United States has been exacerbated due to the socioeconomic strain of the coronavirus disease 2019 (COVID-19) pandemic. Populations experiencing poverty and, as a consequence, food insecurity in the United States are disproportionately affected by obesity, which was identified early in the pandemic as a major risk factor for increased susceptibility to COVID-19 infection and mortality. Given the focus on obesity and its role in immune dysregulation, it is also important to note the role of micronutrient deficiency, another sequalae of food insecurity. Micronutrients play an important role in the ability of the immune system to mount an appropriate response. Moreover, OBESE individuals are more likely to be micronutrient deficient. This review will explore the role of micronutrients, vitamin A, vitamin D, vitamin C, and zinc in respiratory immunity and COVID-19 and how micronutrient deficiency may be a possible confounder in obesity’s association with severe outcomes. By illuminating the role of micronutrients in COVID-19, this paper expands the discussion from food insecurity and obesity to include micronutrient deficiency and how all of these interact in respiratory illnesses such as COVID-19.

Higher risk of vitamin D insufficiency/deficiency for rural than urban dwellers

There are many risk factors for Vitamin D deficiency. This study aimed to compare the Vitamin D status and serum 25(OH)D concentrations of adults living in an urban area to adults living in a rural area in the West of Ireland (latitude 53.27° North). A cross-sectional retrospective analysis of clinical records was performed. Following interrogation of the electronic laboratory information system, individuals who had serum 25(OH)D concentrations measured at Galway University Hospitals between January 2011 and December 2015 were identified. Clinical demographics, setting and date of sampling were recorded. In total, 17,590 patients (urban n = 4,824; rural n = 12,766) were eligible for inclusion. Serum 25(OH)D concentrations were lower among rural compared to urban dwellers irrespective of season (spring p < 0.001, summer p = 0.009, autumn p = 0.002, winter p < 0.001). There was a significant difference in Vitamin D status between urban and rural dwellers in three of the four seasons: spring- deficiency: 16%-v-23%, insufficiency: 39%-v-43%, sufficiency: 45%-v-35% (p < 0.001); autumn- deficiency: 11%-v-10%, insufficiency: 30%-v-35%, sufficiency: 59%-v-56% (p = 0.01); winter- deficiency: 23%-v-25%, insufficiency: 35%-v-42%, sufficiency: 41%-v-33% (p < 0.001). Serum 25(OH)D concentrations were higher and the prevalence of deficiency lower in urban/rural females compared to urban/rural males (p < 0.001). Serum 25(OH)D concentrations increased sequentially from the 18-39 year age group to the 60-69 year age group in both urban (p < 0.001) and rural (p < 0.001) dwellers and then decreased progressively as age increased to ≥90 years. The odds of Vitamin D deficiency increased with age, lower daily sunshine hours, male gender, rural address and season.

Vitamin D status of overweight and obese Bangladeshi adults

Background:

Both obesity and vitamin D deficiency are pandemics and both have influences on cardiovascular parameters. The reported prevalence of vitamin D deficiency in obesity is high. Data relating to vitamin D status in obese is currently lacking in Bangladesh.

Objective:

To discover the vitamin D status in Bangladeshi overweight and obese adults.

Subjects and Methods:

This cross-sectional study, conducted in a specialized endocrine center of Bangladesh, evaluated 500 consecutive overweight or obese subjects, diagnosed according to body mass index (BMI) categories applicable to the south Asian population. Serum 25(OH)D was measured by using the enzyme-linked fluorescent assay (ELFA) method, and the cutoffs described by the Endocrine Society were used to define vitamin D status.

Results:

The mean age of the study subjects was 45.85 (±11.41) years; most (59.6%) of them were in the age group 40–59 years; almost three-fourth (72.4%) were females; an almost equal number of them came from urban (33.8%), semi-urban (29.6%), and rural (36.6%) areas; three-fourth (74.2%) were homemaker. Their mean BMI was 29.54 (±3.11) kg/m²; the frequencies of overweight, class I obesity, class II obesity, and class III obesity were 27.6%, 57.4%, 12.2%, and 2.8%, respectively. The mean serum 25(OH)D level was 25.25 (±11.97) ng/mL. 27.4% were sufficient, and 33.4% were insufficient for vitamin D, whereas 39.2% had vitamin D deficiency. The 25(OH)D level did not differ across different age groups, gender, residence, education status, occupation, and income status. The 25(OH)D levels were also indifferent in overweight, obese class I, obese class II, and obese class III subjects. None of the demographic, anthropometric, and biochemical variables (except low-density lipoprotein cholesterol) correlated with 25(OH)D levels.

Conclusions:

The prevalence of vitamin D deficiency in overweight and obese Bangladeshi adults is very high.

The prevalence of hypovitaminosis D and its risk factors in pregnant women and their newborns in the Middle East: A systematic review

BACKGROUND

Pregnant women and newborns are at risk for vitamin D deficiency (VDD). Also, poor health outcomes for pregnant women with VDD are reported in the published literature.

OBJECTIVE

The aim of this systematic review was to estimate the prevalence of hypovitaminosis D and the associated risk factors for hypovitaminosis D in Middle Eastern pregnant women and their newborns.

RESULTS

The prevalence of circulating 25-hydroxyvitamin D (25(OH)D) < 50 nmol/L as a marker of vitamin D status in pregnant women and their newborns was between 24.5-98% and 22-100%, respectively. The prevalence of 25(OH) D < 25 nmol/L in pregnant women and their newborns was over a wide range between 16.7-80% and 22-82%, respectively. Predictors for low maternal and neonatal 25(OH)D concentrations included decreased vitamin D synthesis due to reduced exposure to sunlight and decreased nutritional intake of vitamin D. A predictor of low neonatal 25(OH)D concentrations included maternal vitamin D status and the correlation between vitamin D concentrations in maternal and cord blood.

CONCLUSION

The high prevalence of VDD in the pregnant women of the Middle East underscores the necessity of implementing national prevention and intervention strategies. A clear policy for clinicians and healthcare workers is needed for screening and maintaining sufficient vitamin D status during pregnancy.

High-Prevalence Vitamin D Deficiency among Korean Emergency Department Homeless, with a Comparison to a Healthy Korean Population

Although nutritional problems are a major concern for the homeless, their vitamin D status has not yet been widely evaluated. This study was a retrospective chart review conducted at a single academic, urban public hospital’s emergency department (ED). Patients whose serum 25-hydroxyvitamin D [25(OH)D] levels had been checked in the ED from July 2014 to June 2015 were reviewed and enrolled. For a healthy settled civilian control, 2011 and 2012 data from the Fifth Korean National Health and Nutrition Examination Survey (KNHANES) were used. A total of 179 patients were enrolled. Vitamin D deficiency was observed in 133 patients (73.7%). The vitamin D deficiency group showed a lower hemoglobin level than that of non-vitamin D deficiency group (p = 0.02). Winter visits were more common among the deficiency group (p = 0.048). Rhabdomyolysis was observed only in the deficiency homeless group (p = 0.03). When using age and sex as covariates of propensity score matching 25(OH)D levels were lower in the homeless than in the healthy control (15.7 ± 7.4 ng/mL vs. 18.2 ± 5.5 ng/mL, p < 0.001). Moreover, when the controls were limited to residents of the same city, the serum 25(OH)D level also was lower in the homeless than in the control (15.7 ± 7.4 ng/mL vs. 17.1 ± 5.4 ng/mL, p = 0.03). In summary, vitamin D deficiency was common and more frequent among homeless patients.

Impact of high latitude, urban living and ethnicity on 25-hydroxyvitamin D status: A need for multidisciplinary action?

The effects of urban living on health are becoming increasingly important, due to an increasing global population residing in urban areas. Concomitantly, due to immigration, there is a growing number of ethnic minority individuals (African, Asian or Middle Eastern descent) living in westernised Higher Latitude Countries (HLC) (e.g. Europe, Canada, New Zealand). Of concern is the fact that there is already a clear vitamin D deficiency epidemic in HLC, a problem which is likely to grow as the ethnic minority population in these countries increases. This is because 25-hydroxyvitamin D (25(OH)D) status of ethnic groups is significantly lower compared to native populations. Environmental factors contribute to a high prevalence of vitamin D deficiency in HLC, particularly during the winter months when there is no sunlight of appropriate wavelength for vitamin D synthesis via the skin. Also, climatic factors such as cloud cover may reduce vitamin D status even in the summer. This may be further worsened by factors related to urban living, including air pollution, which reduces UVB exposure to the skin, and less occupational sun exposure (may vary by individual HLC). Tall building height may reduce sun exposure by making areas more shaded. In addition, there are ethnicity-specific factors which further worsen vitamin D status in HLC urban dwellers, such as low dietary intake of vitamin D from foods, lower production of vitamin D in the skin due to increased melanin and reduced skin exposure to UVB due to cultural dress style and sun avoidance. A multidisciplinary approach applying knowledge from engineering, skin photobiology, nutrition, town planning and social science is required to prevent vitamin D deficiency in urban areas. Such an approach could include reduction of air pollution, modification of sun exposure advice to emphasise spending time each day in non-shaded urban areas (e.g. parks, away from tall buildings), and advice to ethnic minority groups to increase sun exposure, take vitamin D supplements and/or increase consumption of vitamin D rich foods in a way that is safe and culturally acceptable. This review hopes to stimulate further research to assess the impact of high latitude, urban environment and ethnicity on the risk of vitamin D deficiency.

Air pollution, environmental chemicals, and smoking may trigger vitamin D deficiency: Evidence and potential mechanisms

Beyond vitamin D (VD) effect on bone homeostasis, numerous physiological functions in human health have been described for this versatile prohormone. In 2016, 95% of the world's population lived in areas where annual mean ambient particulate matter (<2.5 μm) levels exceeded the World Health Organization guideline value (Shaddick et al., 2018). On the other hand, industries disperse thousands of chemicals continually into the environment. Further, considerable fraction of populations are exposed to tobacco smoke. All of these may disrupt biochemical pathways and cause detrimental consequences, such as VD deficiency (VDD). In spite of the remarkable number of studies conducted on the role of some of the above mentioned exposures on VDD, the literature suffers from two main shortcomings: (1) an overview of the impacts of environmental exposures on the levels of main VD metabolites, and (2) credible engaged mechanisms in VDD because of those exposures. To summarize explanations for these unclear topics, we conducted the present review, using relevant keywords in the PubMed database, to investigate the adverse effects of exposure to air pollution, some environmental chemicals, and smoking on the VD metabolism, and incorporate relevant potential pathways disrupting VD endocrine system (VDES) leading to VDD. Air pollution may lead to the reduction of VD cutaneous production either directly by blocking ultraviolet B photons or indirectly by decreasing outdoor activity. Heavy metals may reduce VD serum levels by increasing renal tubular dysfunction, as well as downregulating the transcription of cytochrome P450 mixed-function oxidases (CYPs). Endocrine-disrupting chemicals (EDCs) may inhibit the activity and expression of CYPs, and indirectly cause VDD through weight gain and dysregulation of thyroid hormone, parathyroid hormone, and calcium homeostasis. Smoking through several pathways decreases serum 25(OH)D and 1,25(OH)2D levels, VD intake from diet, and the cutaneous production of VD through skin aging. In summary, disturbance in the cutaneous production of cholecalciferol, decreased intestinal intake of VD, the modulation of genes involved in VD homeostasis, and decreased local production of calcitriol in target tissues are the most likely mechanisms that involve in decreasing the serum VD levels.

Low serum vitamin D-status, air pollution and obesity: A dangerous liaison

The aim of this review is to provide a general overview of the possible associations among the vitamin D status, air pollution and obesity. Sunlight exposure accounts in humans for more than 90 % of the production of vitamin D. Among emerging factors influencing sunlight-induced synthesis of vitamin D, prospective and observational studies proved that air pollution constitutes an independent risk factor in the pathogenesis of vitamin D hypovitaminosis. In addition, environmental pollutants can affect risk of obesity when inhaled, in combination with unhealthy diet and lifestyle. In turn, obesity is closely associated with a low vitamin D status and many possible mechanisms have been proposed to explain this association. The associations of air pollution with low vitamin D status on the hand and with obesity on the other hand, could provide a rationale for considering obesity as a further link between air pollution and low vitamin D status. In this respect, a vicious cycle could operate among low vitamin D status, air pollution, and obesity, with additive detrimental effects on cardio-metabolic risk in obese individuals. Besides vitamin D supplementation, nutrient combination, used to maximize the protective effects against air pollution, might also contribute to improve the vitamin D status by attenuating the "obesogen" effects of air pollution.

Risk factors for vitamin D deficiency among HIV-infected and uninfected injection drug users

Introduction

Vitamin D deficiency is highly prevalent and is associated with bone disease, cardiovascular disease, metabolic syndrome and malignancy. Injection drug users (IDUs), with or without HIV infection, are at risk for these conditions; however, limited data on vitamin D deficiency exist in this population. We determined the prevalence and correlates of vitamin D deficiency among urban IDUs in the AIDS Linked to the IntraVenous Experience (ALIVE) Study cohort.

Methods

For this cross-sectional sub-study, vitamin D deficiency was defined as a serum 25(OH)-vitamin D level <20 ng/mL. Multivariable logistic regression was used to identify factors independently associated with vitamin D deficiency.

Results

Of 950 individuals analyzed, 29% were HIV-infected. The median age was 49 years; 65% were male, and 91% were black. The median vitamin D level was 13.5 ng/mL (IQR, 9.0–20.3); 74% were deficient (68% in HIV-infected vs. 76% in HIV-uninfected, p = 0.01). Non-black race, fall/winter season, multivitamin intake, higher serum albumin, HCV seropositivity and HIV-infection were associated with significantly lower odds of vitamin D deficiency.

Conclusions

Vitamin D deficiency is prevalent among IDUs. Notably, HIV-infected IDUs were less likely to be vitamin D deficient. Higher vitamin D levels were associated with multivitamin intake and with higher albumin levels, suggesting that nutritional status contributes substantially to deficiency. The association between HCV serostatus and vitamin D level remains unclear. Further investigation is needed to define the clinical implications of the heavy burden of vitamin D deficiency in this high-risk, aging population with significant co-morbidities.

Linking vitamin d deficiency to inflammatory bowel disease

Inflammatory bowel disease is associated with industrialization, and its incidence has increased markedly over time. The prospect of reversing these trends motivates the search for the agent(s) involved. Modernity entails several physical and behavioral modifications that compromise both the photosynthesis of cholecalciferol in the skin and of its bioavailability. Although deficiency in this "vitamin" has therefore emerged as a leading candidate, and despite the publication of a randomized control trial that showed a trend toward statistically significant benefit in Crohn's disease, its causal agency has yet to be demonstrated by an adequately powered study. We discuss the strengths and weaknesses of the case being made by epidemiologists, geneticists, clinicians, and basic researchers, and consolidate their findings into a model that provides mechanistic plausibility to the claim. Specifically, converging data sets suggest that local activation of vitamin D coordinates the activity of the innate and adaptive arms of immunity, and of the intestinal epithelium, in a manner that promotes barrier integrity, facilitates the clearance of translocated flora, and diverts CD4 T cell development away from inflammatory phenotypes. Because smoking is an important risk-altering exposure, we also discuss its newly established melanizing effect and other emerging evidence linking tobacco use to immune function through vitamin D pathways.