The 2011 report on dietary reference intakes for calcium and vitamin D from the Institute of Medicine: what clinicians need to know

Steroid requirements and immune associations with vitamin D are stronger in children than adults with asthma

BACKGROUND

The effects of serum vitamin D status on atopy, steroid requirement, and functional responsiveness to corticosteroids in children versus adults with asthma have not been studied systematically.

OBJECTIVE

We sought to explore the age-specific effects of vitamin D in asthmatic patients.

METHODS

Serum vitamin D levels were examined in a prospective study of adults and children (102 healthy control subjects and 103 asthmatic patients). PBMCs were cultured for 3 hours with or without 100 nmol/L dexamethasone, and the expression of corticosteroid-regulated genes was detected by using real-time PCR. Serum IgE levels were measured, and information about asthmatic patients' steroid requirements was collected.

RESULTS

Deficient serum vitamin D levels (<20 ng/mL) were found in 47.6% of asthmatic patients and 56.8% of healthy control subjects, with means ± SDs of 20.7 ± 9.8 and 19.2 ± 7.7 ng/mL, respectively. In multivariate regression models a significant positive correlation between serum vitamin D levels and the expression of vitamin D-regulated targets, cytochrome P450, family 24, subfamily a (cyp24a) expression by PBMCs (P = .0084, pediatric asthma group only) and serum LL-37 levels (P = .0006 in the pediatric group but P = .0067 in the adult asthma group), was found. An inverse association between vitamin D and serum IgE levels was observed in the pediatric (P = .006) asthma group. Serum vitamin D level (P = .05), as well as PBMC cyp24a expression (P = .0312), demonstrated a significant inverse relationship with daily inhaled corticosteroid dose in the pediatric asthma group only. Cyp24a expression in PBMCs correlated positively with in vitro suppression of TNF-α by dexamethasone (P = .05) and IL-13 (P = .0094) in PBMCs in the pediatric asthma group only.

CONCLUSIONS

This study demonstrated significant associations between serum vitamin D status and steroid requirement and in vitro responsiveness to corticosteroids in the pediatric but not the adult asthma group. Vitamin D was also related to IgE levels in children but not in adults.

Vitamin D in relation to myocardial structure and function after eight years of follow-up: the Hoorn study

BACKGROUND AND AIMS

To investigate associations between baseline serum 25-hydroxyvitamin D [25(OH)D] levels and myocardial structure and function after 8 years of follow-up in older Dutch subjects.

METHODS

We included 256 subjects of the Hoorn Study, a population-based cohort. They underwent a standardized 2-dimensional echocardiogram at baseline between 2000 and 2001, and again between 2007 and 2009. We studied the association of 25(OH)D quartiles with echocardiographic measures of the left ventricular mass index (LVMI), left ventricular systolic function and markers of diastolic function using linear regression analyses.

RESULTS

At baseline, subjects had a mean age of 67.4 ± 5.2 years and 41.4% had prior cardiovascular disease (CVD). Low serum 25(OH)D levels were only associated with higher LVMI at 8-year follow-up in subjects without prior CVD and in subjects with low kidney function (median estimated glomerular filtration rate ≤77.5 ml/min/1.73m(2)). The associations attenuated after adjustments for parathyroid hormone (PTH), which was associated with higher LVMI (g/m(2.7)) in subjects with low kidney function (regression coefficient highest quartile 6.3, 95% CI: 0.2, 12.5).

CONCLUSION

This study showed no strong associations of 25(OH)D with myocardial structure and function. However, PTH - a possible modifiable mediator in the relation between 25(OH)D and myocardial structure - was positively associated with LVMI in subjects with low kidney function.

Vitamin D deficiency is a predictor of reduced survival in patients with heart failure; vitamin D supplementation improves outcome

AIMS

Vitamin D deficiency is a highly prevalent, global phenomenon. The prevalence in heart failure (HF) patients and its effect on outcome are less clear. We evaluated vitamin D levels and vitamin D supplementation in patients with HF and its effect on mortality.

METHODS AND RESULTS

25-Hydroxyvitamin D [25(OH)D] levels were evaluated in HF patients from a health maintenance organization (HMO), and compared them with those of the rest of the members of the HMO. Patients with HF (n = 3009) had a lower median 25(OH)D level compared with the control group (n = 46 825): 36.9 nmol/L (interquartile range 23.2-55.9) vs. 40.7 nmol/L (26.7-56.9), respectively, P < 0.00001. The percentage of patients with vitamin D deficiency [25(OH)D <25 nmol/L] was higher in patients with HF compared with the control group (28% vs. 22%, P < 0.00001). Only 8.8% of the HF patients had optimal 25(OH)D levels (≥75 nmol/L). Median clinical follow-up was 518 days. Cox regression analysis demonstrated that vitamin D deficiency was an independent predictor of increased mortality in patients with HF [hazard ratio (HR) 1.52, 95% confidence interval (CI) 1.21-1.92, P < 0.001] and in the control group (HR 1.91, 95% CI 1.48-2.46, P < 0.00001). Vitamin D supplementation was independently associated with reduced mortality in HF patients (HR 0.68, 95% CI 0.54-0.85, P < 0.0001). Parameters associated with vitamin D deficiency in HF patients were decreased previous solar radiation exposure, body mass index, diabetes, female gender, pulse, and decreased calcium and haemoglobin levels.

CONCLUSIONS

Vitamin D deficiency is highly prevalent in HF patients and is a significant predictor of reduced survival. Vitamin D supplementation was associated with improved outcome.

Vitamin D, osteocalcin, and risk for adiposity as comorbidities in middle school children

Nonclassic actions of vitamin D include potential regulation of immune function and glucose homeostasis. The bone-metabolism loop has recently been expanded to include osteocalcin, which appears to play a more direct role in pancreatic beta cell function and energy metabolism. We hypothesized that both vitamin D and osteocalcin would correlate negatively with indices of adiposity-related comorbidity risk in periadolescents, varying by ethnic group. We analyzed anthropometric, metabolic, and inflammatory markers from a multiethnic population of 106 school children 11 to 14 years of age studied as part of the Reduce Obesity and Diabetes (ROAD) consortium. As expected, 25-hydroxyvitamin D (25-OH vitamin D) was inversely correlated with intact parathyroid hormone (iPTH); total osteocalcin (OCN) and uncarboxylated osteocalcin (uOCN) were directly correlated with each other. OCN and uOCN concentrations correlated inversely with age. Vitamin D deficiency was most prevalent among East Asians (EA) and African Americans (AA). The highest lipid risk scores and homeostatic model for assessment of insulin resistance (HOMA-IR) values were seen in the South Asian (SA) group. Overall, adiposity measures were inversely correlated with OCN and iPTH, whereas such relationships were not observed for vitamin D. Acute insulin response to glucose challenge correlated negatively with uOCN in all subjects; however, lipid risk score correlated negatively with uOCN only in whites. The relationships between markers of calcium metabolism and body composition, glucose homeostasis, lipids, and inflammation all showed racial and ethnic differences. No consistent relationship was found between vitamin D and adiposity or vitamin D and glucose metabolism; instead vitamin D levels varied by race and ethnicity in this school-based group. These findings are consistent with the hypothesis that markers of calcium and bone metabolism may reflect risk for adiposity-related comorbidities in children.

Straight from D-Heart: vitamin D status and cardiovascular disease

PURPOSE OF REVIEW

To offer a comprehensive overview of the best available evidence linking vitamin D status, including the effect of vitamin D supplementation, to the risk of cardiovascular events.

RECENT FINDINGS

There is an abundance of plausible mechanisms by which vitamin D might have a favorable effect on the cardiovascular risk profile in the general population. Epidemiological data strongly support such beneficial effects of vitamin D, but initial enthusiasm is giving way to skepticism as larger, well conducted, longitudinal observational trials fail to show an association between serum vitamin D levels and mortality from cardiovascular events. Moreover, the few existing prospective randomized controlled trials with vitamin D supplementation that report the incidence of cardiovascular events show no effect. Fortunately, larger and better designed prospective trials are underway. Nonetheless, one should also acknowledge that true vitamin D deficiency [<25 nmol/l (10 ng/ml)] remains prevalent in the general population and is convincingly associated with overall adverse outcomes.

SUMMARY

Currently, robust clinical data are lacking to support raising intake requirements and target vitamin D plasma levels based on a role for vitamin D in preventing cardiometabolic diseases. Nonetheless, the high prevalence of vitamin D deficiency in the general population remains alarming and requires implementation of clear supplementation guidelines.

Prevention of vitamin D deficiency in mothers and infants worldwide - a paradigm shift

Vitamin D deficiency in mothers and infants is a global health disorder despite recognition that it is preventable. Recent data support the theory that vitamin D deficiency in adults and children may increase the risk of infections and auto-immune diseases. In most cases, vitamin D deficiency is caused by sunlight deprivation and inadequate corrective vitamin D intake. There is a strong mother/infant vitamin D relationship that affects vitamin D status both in utero and in infancy. Recognition that vitamin D deficiency is a worldwide mother/infant health problem is a basis on which to modify public health strategies to reduce the burden of disease and improve maternal and child vitamin D nutrition. This review provides an update on vitamin D function and the global scope and implications of vitamin D deficiency as it relates to pregnancy and infancy. It also addresses a combined strategy to prevent vitamin D deficiency during pregnancy, lactation and infancy.

Use of vitamin and mineral supplements in long-term care home residents

Vitamin–mineral supplementation may offer older adults health and cognition-related benefits but overuse may contribute to polypharmacy. We examined the prevalence of supplement usage in long-term care facility (LTC) residents (≥65 years of age). As cognition may be affected by nutrition, we also examined use in those with diagnosis of dementia and those with no dementia diagnosis. The prevalence of supplement usage and overall “pill count” from pharmaceutical use was assessed in 189 LTC residents and a subsample of 56 older adults with dementia diagnosis, respectively. Participants were residing in an LTC facility of a mid-size metropolitan area during 2009. The average use of supplements was 1.0 per day for all residents, with 35% taking vitamin D supplements, 20% multivitamins, and 26% calcium. Supplement use was similar (p ≥ 0.05) for those with dementia diagnosis (53%, average 2.0 per day) and for those without such diagnosis (45%, average 2.2 per day). Usage ranged between 1–6 supplements per day. In both of these groups, ∼73% of users were taking vitamin D. The number of prescribed medications ranged from 4 to 24 (average 10.2) in a subsample of residents whose supplement intake was 0 to 6 (average 2). These findings suggest an overall low rate of supplement use, with no significant differences (p ≥ 0.05) in use between residents with and without dementia diagnosis. However, some residents were at risk for supplement overuse.

Serum 25-hydroxyvitamin D, transitions between frailty states, and mortality in older adults: the Invecchiare in Chianti Study

OBJECTIVES

To assess whether serum 25-hydroxyvitamin D (25(OH)D) concentrations relate to transitions between the states of robustness, prefrailty, and frailty and to mortality in older adults.

DESIGN

The Invecchiare in Chianti (InCHIANTI) Study, a prospective cohort study.

SETTING

Tuscany, Italy.

PARTICIPANTS

Adults aged 65 and older (N = 1,155).

MEASUREMENTS

Serum 25(OH)D concentrations measured at baseline; frailty state (robust, prefrail, frail) assessed at baseline and 3 and 6 years after enrollment; and vital status determined 3 and 6 years after enrollment.

RESULTS

The median (interquartile range) 25(OH)D concentration was 16.0 ng/mL (10.4-25.6 ng/mL; multiply by 2.496 to convert to nmol/L). Prefrail participants with 25(OH)D levels less than 20 ng/mL were 8.9% (95% confidence interval (CI) = 2.5-15.2%) more likely to die, 3.0% (95% CI = -5.6-14.6%) more likely to become frail, and 7.7% (95% CI = -3.5-18.7%) less likely to become robust than prefrail participants with 25(OH)D levels of 20 ng/mL or more. In prefrail participants, each 5-ng/mL decrement of continuous 25(OH)D was associated with 1.46 times higher odds of dying (95% CI = 1.18-2.07) and 1.13 higher odds of incident frailty (95% CI = 0.90-1.39) than with recovery of robustness. Transitions from robustness or frailty were not associated with 25(OH)D levels.

CONCLUSION

Results provide evidence that prefrailty is an "at risk" state from which older adults with high 25(OH)D levels are more likely to recover than to decline, but high 25(OH)D levels were not associated with recovery from frailty. Thus, 25(OH)D levels should be investigated as a potential therapy to treat prefrailty and prevent further decline.

Vitamin D: still a topical matter in children and adolescents. A position paper by the Committee on Nutrition of the French Society of Paediatrics

The aims of the present position paper by the Committee on Nutrition of the French Society of Paediatrics were to summarize the recently published data on vitamin D in infants, children and adolescents, i.e., on metabolism, physiological effects, and requirements and to make recommendations on supplementation after careful review of the evidence. Scientific evidence indicates that calcium and vitamin D play key roles in bone health. The current evidence, limited to observational studies, however, does not support other benefits for vitamin D. More targeted research should continue, especially interventional studies. In the absence of any underlying risk of vitamin D deficiency, the recommendations are as follows: pregnant women: a single dose of 80,000 to 100,000 IU at the beginning of the 7th month of pregnancy; breastfed infants: 1000 to 1200 IU/day; children less than 18 months of age, receiving milk supplemented with vitamin D: an additional daily dose of 600 to 800 IU; children less than 18 months of age receiving milk not supplemented with vitamin D: daily dose of 1000 to 1200 IU; children from 18 months to 5 years of age: 2 doses of 80,000 to 100,000 IU every winter (November and February). In the presence of an underlying risk of vitamin D deficiency (dark skin; lack of exposure of the skin to ultraviolet B [UVB] radiation from sunshine in summer; skin disease responsible for decreased exposure of the skin to UVB radiation from sunshine in summer; wearing skin-covering clothes in summer; intestinal malabsorption or maldigestion; cholestasis; renal insufficiency; nephrotic syndrome; drugs [rifampicin; antiepileptic treatment: phenobarbital, phenytoin]; obesity; vegan diet), it may be justified to start vitamin D supplementation in winter in children 5 to 10 years of age as well as to maintain supplementation of vitamin D every 3 months all year long in children 1 to 10 years of age and in adolescents. In some pathological conditions, doses of vitamin D can be increased. If necessary, the determination of 25(OH) vitamin D serum concentration will help determine the level of vitamin D supplementation.

Epidemic vitamin D deficiency among patients in an elderly care rehabilitation facility

BACKGROUND

Many benefits are ascribed to vitamin D beyond its well-known effects on calcium and bone metabolism. Vitamin D in adequate amounts is apparently beneficial to muscle, lessening the risk of falls and fractures in the elderly. The elderly produce less vitamin D in their skin than younger persons do, and they also spend less time in the sun; they are therefore at greater risk of vitamin D deficiency.

METHODS

We used gas chromatography with mass spectrometry coupling to measure the 25-OH-vitamin D level of 1578 elderly persons (72% women) who were consecutively admitted to an elderly care rehabilitation facility in Trier, Germany, from July 2009 to March 2011. Their mean and median age was 82 years.

RESULTS

89% of the patients had 25-OH-vitamin D deficiency (defined as a level below 20 ng/mL), and 67% had a severe deficiency (below 10 ng/mL). Only 4% had levels in the target range (30-60 ng/mL); none had a level above 100 ng/mL.

CONCLUSION

Many of these patients were deficient in vitamin D. Persons of very advanced age need a better supply of vitamin D not only to keep their bones healthy, but also to lessen the risk of falls and fractures.

Vitamin D and breast cancer

In addition to its role in calcium homeostasis and bone health, vitamin D has also been reported to have anticancer activities against many cancer types, including breast cancer. The discovery that breast epithelial cells possess the same enzymatic system as the kidney, allowing local manufacture of active vitamin D from circulating precursors, makes the effect of vitamin D in breast cancer biologically plausible. Preclinical and ecologic studies have suggested a role for vitamin D in breast cancer prevention. Inverse associations have also been shown between serum 25-hydroxyvitamin D level (25(OH)D) and breast cancer development, risk for breast cancer recurrence, and mortality in women with early-stage breast cancer. Clinical trials of vitamin D supplementation, however, have yielded inconsistent results. Regardless of whether or not vitamin D helps prevent breast cancer or its recurrence, vitamin D deficiency in the U.S. population is very common, and the adverse impact on bone health, a particular concern for breast cancer survivors, makes it important to understand vitamin D physiology and to recognize and treat vitamin D deficiency. In this review, we discuss vitamin D metabolism and its mechanism of action. We summarize the current evidence of the relationship between vitamin D and breast cancer, highlight ongoing research in this area, and discuss optimal dosing of vitamin D for breast cancer prevention.

Differences in outcomes between cholecalciferol and ergocalciferol supplementation in veterans with inflammatory bowel disease

AIM

Vitamin D deficiency is a global health issue associated with increased health-care costs, and could play a role in the pathogenesis and management of inflammatory bowel disease. Prior studies show a high prevalence of vitamin D deficiency in veterans with inflammatory bowel disease. We aimed to examine the outcome differences in patients with inflammatory bowel disease, comparing treatment with ergocalciferol to cholecalciferol.

METHODS

A retrospective review of electronic medical records of patients with inflammatory bowel disease at a Veterans Affairs Medical Facility in the Southeastern United States was carried out. Those with at least one serum 25(OH) vitamin D level were included. Initial and follow-up vitamin D values were recorded. The type of vitamin D supplementation, whether cholecalciferol or ergocalciferol, was documented. Costs in the year after measurement of vitamin D were divided into separate inpatient and outpatient categories.

RESULTS

Veterans (n = 108) with ulcerative colitis or Crohn's disease and an available 25(OH) vitamin D level were studied. There were differences in follow-up vitamin D levels; those who received weekly ergocalciferol had higher subsequent levels than those who received cholecalciferol, especially at a second follow up, although differences did not achieve statistical significance. However, those who received vitamin D3 were less likely to use laboratory, pharmacy, radiology and fee-based services, and had lower laboratory and pharmacy costs.

CONCLUSIONS

Our data suggest that cholecalciferol replacement might improve outcomes to a greater extent than ergocalciferol, and might be better in limiting health-care costs and expenses in patients with inflammatory bowel disease.

The Vitamin D Receptor, Inflammatory Bowel Diseases, and Colon Cancer

The nuclear receptor is an emerging therapeutic target in various human diseases. Vitamin D receptor (VDR), a nuclear receptor, mediates the biological functions of vitamin D. Classically, vitamin D is recognized as an essential contributor to mineral and bone homeostasis. Increasing evidence demonstrates that vitamin D is involved in inflammatory responses. Persistent intestinal inflammation is associated with colon cancer. This review focuses on vitamin D and VDR in inflammatory bowel diseases and colon cancer. We place emphasis on the regulatory roles of vitamin D/VDR on in inflammation, enteric bacteria, and tumorigenesis. We summarize the signaling pathways regulated by VDR in intestinal homeostasis. Finally, we discuss the potential application of the insights gleaned from these findings to personalized therapies in chronic inflammation and colon cancer.

Vitamin D deficiency in obese children and its relationship to glucose homeostasis

OBJECTIVES

The aim of the study was to compare the prevalence of vitamin D deficiency in obese and non-overweight children in North Texas, to examine relationships between dietary habits and 25-hydroxyvitamin D [25(OH)D] level in obese children, and to examine the relationship between 25(OH)D level and markers of abnormal glucose metabolism and blood pressure.

PATIENTS AND METHODS

Using a cross-sectional design, systolic and diastolic blood pressure, dietary information, serum 25(OH)D, fasting glucose and insulin, 2-h glucose from oral glucose tolerance test, hemoglobin A1c, and homeostasis model assessment of insulin resistance were recorded for 411 obese subjects (6-16 yr old) at an obesity referral clinic. 25(OH)D was also obtained from 87 control non-overweight subjects (6-16 yr old).

RESULTS

Ninety-two percent of obese subjects had a 25(OH)D level below 75 nmol/liter, and 50% were below 50 nmol/liter. Among non-overweight subjects, these frequencies were 68 and 22%, respectively (both P < 0.01 compared with obese subjects). 25(OH)D was negatively associated with soda intake (P < 0.001), juice intake (P = 0.009), and skipping breakfast (P < 0.001). 25(OH)D was negatively correlated with homeostasis model assessment of insulin resistance (r = -0.19; P = 0.001) and 2-h glucose (r = -0.12; P = 0.04) after adjustment for body mass index and age but was not correlated with hemoglobin A1c, systolic blood pressure Z score, or diastolic blood pressure Z score.

CONCLUSIONS

Vitamin D deficiency is common in children in this southern United States location and is significantly more prevalent in obese children. Lower 25(OH)D level is associated with risk factors for type 2 diabetes in obese children.

Associations of Sun Exposure with 25-Hydroxyvitamin D and Parathyroid Hormone Levels in a Cohort of Hypertensive Patients: The Graz Endocrine Causes of Hypertension (GECOH) Study

Sunlight-induced vitamin D, synthesis in the skin is the major source of vitamin D, but data on the relationship of sun-related behaviour with vitamin D and parathyroid hormone (PTH) levels are relatively sparse. We evaluated whether habitual sun exposure is associated with 25-hydroxyvitamin D (25[OH]D) and PTH levels and whether there exist seasonal variations. We examined 111 hypertensive patients in Austria (latitude 47° N). Frequent sunbathing at home and outdoor sports were associated with higher 25(OH)D levels (P < 0.05 for both). Red or blond scalp hair as a child, memory of sunburns, preferring sunbathing, frequent stays on the beach or in open-air pools, and solarium use were associated with lower PTH levels (P < 0.05 for all). Multiple linear regression analyses including age, sex, and body mass index showed that sun exposure score was significantly associated with 25(OH)D (beta coefficient = 0.27; P = 0.004) and by trend with PTH (beta coefficient = -0.16; P = 0.09). These associations were more prominent in summer in which 25(OH)D levels were significantly higher compared to winter. Translation of these findings into recommendations for the prevention and treatment of vitamin D deficiency remains a challenge for the future.

Vitamin D deficiency and mortality risk in the general population: a meta-analysis of prospective cohort studies

BACKGROUND

Low vitamin D status may increase mortality risk.

OBJECTIVE

We used nonparametric ("highest compared with lowest" categories) and parametric (>2 categories) statistical models to evaluate associations of 25-hydroxyvitamin D [25(OH)D] serum concentrations and mortality in observational studies among general populations.

DESIGN

We searched PubMed, EMBASE, Web of Science, and reference lists for relevant articles. We included studies that contained data on relative risks (RRs) for mortality for different 25(OH)D concentrations, which included a corresponding measure of uncertainty, and this yielded 14 prospective cohort studies that involved 5562 deaths out of 62,548 individuals. We applied log-transformed RRs and CIs, adjusted for the maximal number of confounding variables. In the parametric model, which is based on 11 studies and 59,231 individuals, we used the lowest quantile as the reference category.

RESULTS

For "highest compared with lowest" categories of 25(OH)D, the estimated summary RR of mortality was 0.71 (95% CI: 0.50, 0.91). In the parametric model, the estimated summary RRs (95% CI) of mortality were 0.86 (0.82, 0.91), 0.77 (0.70, 0.84), and 0.69 (0.60, 0.78) for individuals with an increase of 12.5, 25, and 50 nmol 25(OH)D serum values/L, respectively, from a median reference category of ∼27.5 nmol/L. There was, however, no significant decrease in mortality when an increase of ∼87.5 nmol/L above the reference category occurred.

CONCLUSION

Data suggest a nonlinear decrease in mortality risk as circulating 25(OH)D increases, with optimal concentrations ∼75-87.5 nmol/L.

The VITamin D and OmegA-3 TriaL (VITAL): rationale and design of a large randomized controlled trial of vitamin D and marine omega-3 fatty acid supplements for the primary prevention of cancer and cardiovascular disease

Data from laboratory studies, observational research, and/or secondary prevention trials suggest that vitamin D and marine omega-3 fatty acids may reduce risk for cancer or cardiovascular disease (CVD), but primary prevention trials with adequate dosing in general populations (i.e., unselected for disease risk) are lacking. The ongoing VITamin D and OmegA-3 TriaL (VITAL) is a large randomized, double-blind, placebo-controlled, 2 x 2 factorial trial of vitamin D (in the form of vitamin D(3) [cholecalciferol], 2000 IU/day) and marine omega-3 fatty acid (Omacor fish oil, eicosapentaenoic acid [EPA]+docosahexaenoic acid [DHA], 1g/day) supplements in the primary prevention of cancer and CVD among a multi-ethnic population of 20,000 U.S. men aged ≥ 50 and women aged ≥ 55. The mean treatment period will be 5 years. Baseline blood samples will be collected in at least 16,000 participants, with follow-up blood collection in about 6000 participants. Yearly follow-up questionnaires will assess treatment compliance (plasma biomarker measures will also assess compliance in a random sample of participants), use of non-study drugs or supplements, occurrence of endpoints, and cancer and vascular risk factors. Self-reported endpoints will be confirmed by medical record review by physicians blinded to treatment assignment, and deaths will be ascertained through national registries and other sources. Ancillary studies will investigate whether these agents affect risk for diabetes and glucose intolerance; hypertension; cognitive decline; depression; osteoporosis and fracture; physical disability and falls; asthma and other respiratory diseases; infections; and rheumatoid arthritis, systemic lupus erythematosus, thyroid diseases, and other autoimmune disorders.

Response to vitamin D3 supplementation in obese and non-obese Caucasian adolescents

BACKGROUND/AIMS

Vitamin D deficiency is highly prevalent in obese children, and obese children tend to respond poorly to vitamin D supplementation. The objective of the study was to compare the response to vitamin D(3) supplementation (2,000 IU once daily for 12 weeks) between obese and non-obese Caucasian adolescents.

METHODS

The study design was open label non-randomized. It was carried out at a single center. Eighteen obese adolescents (aged 12-18 years) and the same number of age-, gender- and season-matched non-obese adolescents received vitamin D(3) (2,000 IU/day) orally for 12 weeks. Total serum 25-hydroxyvitamin D [25(OH)D], parathyroid hormone, calcium and phosphorus were measured at baseline and at the end of the 12-week period.

RESULTS

The mean baseline 25(OH)D level was higher in the non-obese compared to the obese subjects (mean 28.9 vs. 25.2 ng/ml; p = 0.029). The increment in 25(OH)D levels following vitamin D supplementation was significantly lower in the obese adolescents (mean change 5.8 vs. 9.8 ng/ml; p = 0.019).

CONCLUSIONS

Higher doses of vitamin D are required to treat vitamin D deficiency in obese adolescents compared to their non-obese peers.

Lack of efficacy of ergocalciferol repletion

INTRODUCTION

Vitamin D has become an area of intensive scrutiny, both in medical and lay literature. However, there are limited data to suggest proper repletion regimens for those patients who have hypovitaminosis D. Consequently, various methods are used in clinical practice. The aim of this study was to assess the efficacy of various treatment strategies for hypovitaminosis D in an ambulatory internal medicine practice.

METHODS

A retrospective chart review between October 2005 and June 2010 of a suburban internal medicine practice was performed via query of the electronic medical record (Centricity, General Electric Healthcare, UK). Patients with a 25-hydroxyvitamin D concentration less than 32 mg/dl were identified and treated. Treatment success was defined as 25-hydroxyvitamin D concentrations greater than 32 mg/dl. Statistical analysis to assess changes in vitamin D level controlling for season, comorbidities, and demographics were used.

RESULTS

A total of 607 treatment episodes were identified, with 395 excluded due to lack of follow-up vitamin D level within 16 weeks, no treatment documented, topical treatment, doxercalciferol treatment, or non-compliance. Of the remaining patients, there were 212 treatment instances on 178 patients. Ergocalciferol 50,000 international units (IU) was used most frequently (71.4% of the time.). A higher initial vitamin D level was positively associated with treatment success (adjusted odds ratio = 1.11, p=0.002). Increased doses of ergocalciferol increased the likelihood of treatment success (p=0.0011). Seasonal variation was related to posttreatment 25-hydroxyvitamin D concentration as was body mass index (BMI) (p=0.003 and p=0.044).

CONCLUSION

Pretreatment levels of 25-hydroxyvitamin D, BMI, season, and vitamin D dose are predictors of successful hypovitaminosis D treatment. Our data suggest that patients with initial 25-hydroxyvitamin D concentrations of <20 should be treated with a higher total dose of ergocalciferol than 50,000 IU for 8 weeks. Further studies, including prospective, randomized trials, are needed to determine an optimal treatment protocol to account for the numerous variables.

Proceedings of the 2011 Santa Fe Bone symposium

The 11th Santa Fe Bone Symposium was held in Santa Fe, NM, USA, on August 6-7, 2010. This annual event addresses the clinical relevance of recent scientific advances in the fields of osteoporosis and metabolic bone disease. The symposium format included plenary presentations, oral abstracts, and interactive panel discussions, with participation of clinicians, researchers, and bone densitometry technologists. Among the many topics included in the symposium were new developments in nutritional therapy for osteoporosis, parathyroid hormone for the assessment and treatment of skeletal disease, osteoporosis in men, new and emerging concepts in osteoporosis therapy, report on the 2010 International Society for Clinical Densitometry (ISCD)-International Osteoporosis Foundation FRAX Initiative and the ISCD Position Development Conference, balancing benefits and risks of bisphosphonate therapy, and an advanced bone densitometry workshop for clinicians and technologists.

Is dietary fat, vitamin D, or folate associated with pancreatic cancer?

Although potentially modifiable risk factors for pancreatic cancer include smoking, obesity, and diabetes, less is known about the extent to which diet affects cancer risk. Recent studies have demonstrated some consistency for dietary fat being associated with elevated pancreatic cancer risk, particularly from animal sources. However, less is known about which fatty acids pose the greatest risk. Vitamin D, due to its endogenous production following UV-B exposure, is a unique risk factor in that researchers have created several methods to assess its exposure in humans. Studies that measured vitamin D exposure differently have shown inconsistent results. Dietary studies suggest protective associations, whereas studies of circulating 25-hydroxyvitamin D status show null or positive associations with low or very high concentrations, respectively. Several, but not all epidemiologic studies provide evidence of an inverse relationship between total and/or dietary folate and risk of pancreatic cancer. Protective associations for circulating folate are more often observed among populations with inadequate status. This article reviews the current epidemiological and experimental evidence investigating the relationship of dietary fat, vitamin D, and folate with pancreatic cancer. Additionally the mechanisms by which these risk factors may contribute to cancer, the methodological challenges involved with assessing risk, and other obstacles encountered when ascertaining the magnitude and direction of these three exposures are discussed.

Vitamin D intake and mental health-related quality of life in older women: the Iowa Women's Health Study

OBJECTIVE

Vitamin D deficiency and mood disorders are both prevalent among the elderly. We evaluated the association between vitamin D intake and mental health-related quality of life (QOL) among elderly women participating in a large population-based study.

STUDY DESIGN

This study was a cross-sectional analysis of the Iowa Women's Health Study, a prospective study of cancer risk factors among post-menopausal women in Iowa that began in 1986. Additional survey data was collected from the cohort members in 1987, 1989, 1992, 1997, and 2004. Data for this analysis came from the 2004 questionnaire.

MAIN OUTCOME MEASURE

Mental health-related QOL was assessed using five scales from the Medical Outcomes Study 36-item Short-form Health Survey. QOL scores were analyzed as continuous variables using linear regression, controlling for age, energy intake, BMI, education, smoking, living arrangement, antidepressant usage, comorbidity history, and physical activity.

RESULTS

Low vitamin D intake (<400 IU/day) was associated with poorer QOL scores compared to women with higher intake (≥400 IU/day). Differences in QOL scores by vitamin D intake group were attenuated with multivariable adjustment, but a significant overall association between vitamin D and QOL scores persisted. Further adjustment for physical activity attenuated all differences as well as the overall association between vitamin D and QOL scores.

CONCLUSIONS

Women who consumed <400 IU/day of vitamin D had significantly lower mental health-related QOL compared to those who consumed ≥400 IU/day. Meeting dietary vitamin D recommendations is a potential method for improving QOL among the elderly.

Vitamin D deficiency is common in children and adolescents with chronic kidney disease

Here we determined if vitamin D deficiency is more common in children with chronic kidney disease compared to healthy children. In addition, we sought to identify disease-specific risk factors for this deficiency, as well as its metabolic consequences. We found that nearly half of 182 patients (ages 5 to 21) with kidney disease (stages 2 to 5) and a third of age-matched 276 healthy children were 25-hydroxyvitamin D deficient (<20 ng/ml). The risk of deficiency was significantly greater in advanced disease. Focal segmental glomerulosclerosis and low albumin were significantly associated with lower 25-hydroxyvitamin D, which, in turn, was associated with significantly higher intact parathyroid hormone levels. We found that 25-hydroxyvitamin D levels were positively associated with 1,25-dihydroxyvitamin D, the relationship being greatest in advanced disease (significant interaction), and inversely related to those of inflammatory markers C-reactive protein and IL-6. The association with C-reactive protein persisted when adjusted for the severity of kidney disease. Thus, lower 25-hydroxyvitamin D may contribute to hyperparathyroidism, inflammation, and lower 1,25-dihydroxyvitamin D in children and adolescents, especially those with advanced kidney disease.

Progesterone and vitamin d hormone as a biologic treatment of traumatic brain injury in the aged

There is growing recognition that traumatic brain injury is a highly variable and complex systemic disorder that is refractory to therapies that target individual mechanisms. It is even more complex in elderly persons, in whom frailty, previous comorbidities, altered metabolism, and a long history of medication use are likely to complicate the secondary effects of brain trauma. Progesterone, one of the few neuroprotective agents that has shown promise for the treatment of acute brain injury, is now in national and international phase 3 multicenter trials. New findings show that vitamin D hormone (VDH) and VDH deficiency in the aging process (and across the developmental spectrum) may interact with progesterone and treatment for traumatic brain injury. In this article we review the use of progesterone and VDH as biologics-based therapies along with recent studies demonstrating that the combination of progesterone and VDH may promote better functional outcomes than either treatment independently.

Effects of vitamin D3 and calcium supplementation on serum levels of tocopherols, retinol, and specific vitamin D metabolites

γ-Tocopherol (γT) protects against DNA-damaging effects of nitrogen oxides, yet its physiologic regulation in vivo is unknown. Observational studies indicate inverse associations of 25[OH]-vitamin D with γT and leptin. To determine whether vitamin D(3) supplementation alters levels of lipid-soluble micronutrients, serum samples (N = 85 subjects) from a randomized, double-blind, placebo-controlled clinical trial of vitamin D(3) (800 IU) and calcium (2 g), alone and in combination, were analyzed for lipid micronutrients and specific vitamin D metabolites at baseline and after 6 mo of supplementation. Serum 25[OH]-vitamin D(3) levels increased 55% (P < 0.0001) and 48% (P = 0.0005), whereas 25[OH]-vitamin D(2) levels were lower by 48% (P = 0.26) and 21% (P = 0.36) in the vitamin D(3) and vitamin D(3) plus calcium groups, respectively. At baseline, γT levels were inversely associated with 25[OH]D (r = -0.31, P = 0.004). With vitamin D(3) plus calcium treatment, serum α-tocopherol decreased 14% (P = 0.04), whereas similar changes in γT (19% lower, P = 0.14) were observed. No significant effects were observed for D(3) supplementation on leptin or retinol levels. These results are consistent with the hypothesis that vitamin D(3) ± calcium affects serum tocopherol and 25[OH]D(2) levels; however, studies using larger, more homogeneous populations are warranted.

Vitamin D safety and requirements

Vitamin D an ancient secosteroid is essential for mineral homeostasis, bone remodeling, immune modulation, and energy metabolism. Recently, debates have emerged about the daily vitamin D requirements for healthy and elderly adults, the safety and efficacy of long term supplementation and the role of vitamin D deficiency in several chronic disease states. Since this molecule acts as both a vitamin and a hormone, it should not be surprising that the effects of supplementation are multi-faceted and complex. Yet despite significant progress in the last decade, our understanding of vitamin D physiology and the clinical relevance of low circulating levels of this vitamin remains incomplete. The present review provides the reader with a comprehensive and up-to-date understanding of vitamin D requirements and safety. It also raises some provocative research questions.

Serum 25-hydroxyvitamin D and pulmonary function in older disabled community-dwelling women

BACKGROUND

Recent studies have expanded the functions of vitamin D to a possible role in pulmonary function. Our objective was to examine the relationship between serum 25-hydroxyvitamin D (25[OH]D), serum parathyroid hormone, and pulmonary function in older women.

METHODS

We examined the relationship of serum 25(OH)D and parathyroid hormone with pulmonary function (forced expiratory volume in one second [FEV(1)], forced vital capacity [FVC], and FEV(1)/FVC ratio) in a cross-sectional study of 646 moderately to severely disabled women, 65 years or more, living in the community in Baltimore, Maryland, who participated in the Women's Health and Aging Study I.

RESULTS

Overall, median (25th, 75th percentile) serum 25-hydroxyvitamin D concentrations were 19.9 (14.7, 26.7) ng/mL. Serum 25(OH)D was positively associated with FEV(1) (p = .03), FVC (p = .18), and FEV(1)/FVC (p = .04) in multivariable linear regression models adjusting for age, race, education, smoking, height, physical activity, cognition, interleukin-6, chronic diseases, and other potential confounders. In the same models, serum parathyroid hormone was not significantly associated with FEV(1), FVC, or FEV(1)/FVC.

CONCLUSIONS

These findings support the idea that vitamin D deficiency is independently associated with poor pulmonary function in older disabled women.

Vitamin D-mentia: randomized clinical trials should be the next step

Hypovitaminosis D is highly prevalent in the elderly. Its possible role in the pathogenesis of Alzheimer's disease (AD) is particularly important, as AD remains a public health concern with no current efficient treatment. Vitamin D administration could be a multitarget stabilizing treatment for AD since vitamin D simultaneously targets several factors leading to neurodegeneration through immunoregulatory, antioxidant and anti-ischemic actions, as well as the regulation of neurotrophic factors, acetylcholine neurotransmitter and clearance of amyloid beta peptide, and the avoidance of hyperparathyroidism. By preventing neuronal loss, the question is whether correcting hypovitaminosis D among older adults could also prevent AD-related cognitive decline. The cross-sectional associations between the vitamin D intakes--whether from diet, sun exposure or drug supplements--and cognition strengthened this hypothesis, but prevented the finding of a cause and effect link. Pre-post studies showed an improvement of cognition concomitant with the increase in 25-hydroxyvitamin D concentrations. One randomized trial found that supraphysiological doses of vitamin D were not better than physiological doses at improving cognition in AD. At this stage, only clinical trials testing vitamin D supplements versus placebo can further determine the impact of vitamin D administration on cognition and AD with higher levels of evidence.

Vitamin D metabolism and activity in the parathyroid gland

Parathormone (PTH) and vitamin D are two critical hormonal regulators of calcium homeostasis. An important cross-talk exists between the PTH and vitamin D hormonal systems. PTH enhances vitamin D hydroxylation on carbon 1 in kidney cells thereby allowing the systemic release of 1-25-dihydroxy-vitamin D, which represents the fully active hormone. Conversely, parathyroid gland represents a direct target for vitamin D. Parathyroid cells express the vitamin D receptor and the 1-α-hydroxylase enzyme, which allows the local formation of 1-25-dihydroxy-vitamin D. Because of its potential implication in several diseases, including osteoporosis or chronic kidney disease, the interplay between PTH and vitamin D has received considerable attention these last two decades. The aim of this review is to summarize our current understanding of the molecular basis of vitamin D action and metabolism in parathyroid cells. The potential clinical implications of the recent advances made in this field will also be discussed.

Vitamin D and diabetes: its importance for beta cell and immune function

Experimental evidence indicates that vitamin D may play a role in the defense against type 1 diabetes (T1D) as well as type 2 diabetes (T2D). Epidemiological data have established a link between vitamin D deficiency and an increased incidence of both T1D and T2D, whereas early and long-term vitamin D supplementation may decrease the risk of these disorders. The protective effects of vitamin D are mediated through the regulation of several components such as the immune system and calcium homeostasis. However, an increasing amount of evidence suggests that vitamin D also affects beta cells directly thereby rendering them more resistant to the types of cellular stress encountered during T1D and T2D. This review evaluates the role of vitamin D signaling in the pathogenesis of T1D and T2D with a special emphasis on the direct effects of vitamin D on pancreatic beta cells.

Vitamin D, the placenta and pregnancy

Impaired vitamin D status is common to many populations around the world. However, data suggest that this is a particular problem for specific groups such as pregnant women. This has raised important questions concerning the physiological and clinical impact of low vitamin D levels during pregnancy, with implications for classical skeletal functions of vitamin D, as well as its diverse non-classical actions. The current review will discuss this with specific emphasis on the classical calciotropic effects of vitamin D as well as the less well established immunological functions of vitamin D that may influence pregnancy outcome. The review also describes the pathways that are required for metabolism and function of vitamin D, and the various clinical complications that have been linked to impaired vitamin D status during pregnancy.

Association of glucocorticoid use and low 25-hydroxyvitamin D levels: results from the National Health and Nutrition Examination Survey (NHANES): 2001-2006

CONTEXT

In many disorders requiring steroid therapy, there is substantial decrease in bone mineral density. The association between steroid use and 25-hydroxyvitamin D [25(OH)D] deficiency has not been confirmed in large population-based studies, and currently there are no specific vitamin D recommendations for steroid users.

OBJECTIVE

The aim of the study was to evaluate the association of serum 25(OH)D deficiency [defined as 25(OH)D <10 ng/ml] with oral steroid use.

DESIGN

Cross-sectional analysis was performed using NHANES 2001-2006.

SETTING

We analyzed a nationally representative sample of U.S. children and adults.

PARTICIPANTS

The study sample consisted of children, adolescents, and adults from NHANES 2001-2006 (n = 22,650), representative of 286 million U.S. residents, with serum 25(OH)D levels and data on other potential confounders.

MAIN OUTCOME MEASURE

We measured serum 25(OH)D levels below 10 ng/ml.

RESULTS

A total of 181 individuals (0.9% of the population) used steroids within the past 30 d. Overall, 5% of the population had 25(OH)D levels below 10 ng/ml. Among steroid users, 11% had 25(OH)D levels below 10 ng/ml, compared to 5% among steroid nonusers (P = 0.009). The odds of having 25(OH)D deficiency were 2-fold higher in those who reported steroid use compared to those without steroid use [odds ratio (OR), 2.36; 95% confidence interval (CI), 1.25, 4.45]. This association remained after multivariable adjustment (OR, 2.21; 95% CI, 1.01, 4.85) and in a multivariable model using NHANES III data (OR, 1.88; 95% CI, 1.01, 3.48).

CONCLUSION

Steroid use is independently associated with 25(OH)D deficiency in this nationally representative cohort limited by cross-sectional data. It suggests the need for screening and repletion in patients on chronic steroids.

Vitamin D deficiency is associated with short stature and may influence blood pressure control in paediatric renal transplant recipients

Vitamin D deficiency is common in adult renal transplant recipients, but data in children are scarce. Vitamin D is shown to have multiple effects on the cardiovascular system, renal function, and maintenance of bone health. We hypothesized that 25(OH)D deficiency is common in pediatric renal transplant recipients, and may be associated with hyperparathyroidism, short stature, renal function, and blood pressure control. We recruited 106 children during the winter/spring season who had a functioning renal transplant for at least 3 months. Twenty-five hydroxyvitamin D [25(OH)D] and 1,25-dihydroxyvitamin D [1,25(OH)(2)D] were measured and correlated with clinical and biochemical parameters. Of the renal transplant patients, 38% were 25(OH)D deficient, 54% had insufficient levels, and only 8% had adequate 25(OH)D levels. Despite alfacalcidol supplementation in 59 (56%) patients, parathyroid hormone was increased in 58 (55%) and showed an inverse correlation with 25(OH)D (p = 0.0003, r = 0.61) but not with 1,25(OH)(2)D levels. Height standard deviation score (SDS) correlated with 25(OH)D (p = 0.007, r = 0.42) and time post transplantation (p = 0.02, r = 0.23); both were significant and independent predictors of height SDS. 25(OH)D inversely correlated with systolic BP SDS (p = 0.02, r =-0.26); this association was lost on multiple regression analysis, but 25(OH)D was the only modifiable risk factor for hypertension. There was no correlation with estimated GFR or proteinuria. In conclusion, 25(OH)D deficiency is common in pediatric renal transplant recipients and correlates with hyperparathyroidism and short stature. 25(OH)D deficiency may be a modifiable risk factor for hypertension in transplant recipients. Further studies are required to test if routine supplementation with ergo or cholecalciferol is safe and effective in children after renal transplantation.

Is vitamin D a determinant of muscle mass and strength?

There remains little consensus on the link between vitamin levels and muscle mass or strength. We therefore investigated the association of serum 25-hydroxyvitamin D (25(OH)D), 1,25-dihydroxyvitamin D (1,25(OH)(2) D), and parathyroid hormone (PTH) levels with skeletal muscle mass and strength. We studied 311 men (mean age, 56 years; range, 23-91 years) and 356 women (mean age, 57 years; range, 21-97 years) representing an age-stratified, random sample of community adults. Multivariate linear regression models were used to examine the association of skeletal muscle mass (by total body dual-energy X-ray absorptiometry) and strength (handgrip force and isometric knee extension moment) with each of 25(OH)D, 1,25(OH)(2) D, and PTH quartiles, adjusted for age, physical activity, fat mass, and season. We found no consistent association between 25(OH)D or PTH and any of our measurements of muscle mass or strength, in either men or women. However, in subjects younger than 65 years, there was a statistically significant association between low 1,25(OH)(2) D levels and low skeletal mass in both men and women and low isometric knee extension moment in women, after adjustment for potential confounders. Modestly low 25(OH)D or high PTH levels may not contribute significantly to sarcopenia or muscle weakness in community adults. The link between low 25(OH)D and increased fall risk reported by others may be due to factors that affect neuromuscular function rather than muscle strength. The association between low 1,25(OH)(2) D and low skeletal mass and low knee extension moment, particularly in younger people, needs further exploration.

Disorders of calcium metabolism and parathyroid disease

Pregnancy and lactation are associated with profound changes in calcium physiology. This can make interpretation of biochemical tests difficult during these times. Diseases of bone and calcium metabolism are uncommon during pregnancy but can be severe when they occur. These conditions are complicated by the need for dual consideration for the maternal and foetal health. These conditions are also much less well studied than related conditions that occur outside of pregnancy resulting in a reduction in evidence for and confidence in recommendations relating to management. This chapter will review the changes in calcium physiology that occur with pregnancy and lactation, describe the disorders of calcium and parathyroid physiology that can occur and outline the most appropriate way to manage these conditions.

Cataract and ovarian carcinoma: is the vitamin D hypothesis alive?

BACKGROUND

The major health benefit of exposure to solar UV radiation is the production of vitamin D, which is implicated in protection against several human cancers, including ovarian carcinoma. On the other hand, solar UV radiation is a recognized risk factor for cataract.

METHODS

This population-based case-control study of 709 women with primary invasive ovarian carcinoma and 1,101 controls examined the association of ovarian carcinoma risk with self-reported history of cataract as an indicator of high long-term exposure to UV radiation. ORs and 95% confidence intervals (CI) were estimated using multivariate logistic regression models.

RESULTS

Among controls, older age (P < 0.0001), history of type 2 diabetes (P = 0.04), and skin cancer (P = 0.03) were significant cataract risk predictors. A history of cataract, reported by 14% of cases and 17% of controls, was significantly associated with a reduced ovarian carcinoma risk (OR = 0.6; 95% CI, 0.4-0.8; P = 0.002). No heterogeneity was observed by tumor histology, stage, grade, study site, body mass index, or other ovarian cancer risk factors (P > 0.16).

CONCLUSION

These findings add indirect evidence to the hypothesis that lifetime vitamin D exposure may be inversely associated with risk of ovarian carcinoma.

IMPACT

The study suggests some potential new avenues for research. Additional studies are needed to further investigate the potential behavioral and biologic factors that might influence association of cataract with ovarian cancer.

Vitamin D and respiratory infection in adults

Vitamin D insufficiency is a global issue that has significant implications for health. The classical role of vitamin D in bone mineralisation is well known; vitamin D deficiency leads to rickets, osteomalacia or osteoporosis. The role of vitamin D in an immune system is less known. Vitamin D is not an actual vitamin but a secosteroid hormone produced in the skin from 7-dehydrocholesterol after exposure to sunlight UVB radiation. Nutrition and supplements are main sources of vitamin D in wintertime in northern countries as sunlight exposure is inadequate for the production. For activation vitamin D needs to be hydroxylated in liver to form 25-hydroxyvitamin D and in kidney to 1,25-dihydroxyvitamin D, the most active hormone in Ca absorption in the gut. For determination of vitamin D status serum 25-hydroxyvitamin D level, the major circulating form of the hormone is to be measured. Vitamin D regulates gene expression through binding with vitamin D receptors, which dimerises with retinoid X receptor. This complex binds to vitamin D-responsive elements inside the promoter regions of vitamin D-responsive genes. Vitamin D has a key role in innate immunity activation; the production of antimicrobial peptides (cathelicidin and defensins) following Toll-like receptor stimulation by pathogen lipopeptides is dependent on sufficient level of 25-hydroxyvitamin D. Clinically, there is evidence of the association of vitamin D insufficiency and respiratory tract infections. There is also some evidence of the prevention of infections by vitamin D supplementation. Randomised controlled trials are warranted to explore this preventive effect.

Regular consumption of vitamin D-fortified yogurt drink (Doogh) improved endothelial biomarkers in subjects with type 2 diabetes: a randomized double-blind clinical trial

BACKGROUND

Endothelial dysfunction has been proposed as the underlying cause of diabetic angiopathy that eventually leads to cardiovascular disease, the major cause of death in diabetes. We recently demonstrated the ameliorating effect of regular vitamin D intake on the glycemic status of patients with type 2 diabetes (T2D). In this study, the effects of improvement of vitamin D status on glycemic status, lipid profile and endothelial biomarkers in T2D subjects were investigated.

METHODS

Subjects with T2D were randomly allocated to one of the two groups to receive either plain yogurt drink (PYD; containing 170 mg calcium and no vitamin D/250 mL, n1 = 50) or vitamin D3-fortified yogurt drink (FYD; containing 170 mg calcium and 500 IU/250 mL, n2 = 50) twice a day for 12 weeks. Anthropometric measures, glycemic status, lipid profile, body fat mass (FM) and endothelial biomarkers including serum endothelin-1, E-selectin and matrix metalloproteinase (MMP)-9 were evaluated at the beginning and after the 12-week intervention period.

RESULTS

The intervention resulted in a significant improvement in fasting glucose, the Quantitative Insulin Check Index (QUICKI), glycated hemoglobin (HbA1c), triacylglycerols, high-density lipoprotein cholesterol (HDL-C), endothelin-1, E-selectin and MMP-9 in FYD compared to PYD (P < 0.05, for all). Interestingly, difference in changes of endothelin-1, E-selectin and MMP-9 concentrations in FYD compared to PYD (-0.35 ± 0.63 versus -0.03 ± 0.55, P = 0.028; -3.8 ± 7.3 versus 0.95 ± 8.3, P = 0.003 and -2.3 ± 3.7 versus 0.44 ± 7.1 ng/mL, respectively, P < 0.05 for all), even after controlling for changes of QUICKI, FM and waist circumference, remained significant for endothelin-1 and MMP-9 (P = 0.009 and P = 0.005, respectively) but disappeared for E-selectin (P = 0.092). On the contrary, after controlling for serum 25(OH)D, the differences disappeared for endothelin-1(P = 0.066) and MMP-9 (P = 0.277) but still remained significant for E-selectin (P = 0.011).

CONCLUSIONS

Ameliorated vitamin D status was accompanied by improved glycemic status, lipid profile and endothelial biomarkers in T2D subjects. Our findings suggest both direct and indirect ameliorating effects of vitamin D on the endothelial biomarkers.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT01236846.

How to stay heart healthy in 2011: considerations for the primary prevention of cardiovascular disease in women

More women die of cardiovascular disease than any other cause. Effective primary prevention depends on accurate assessment of risk status. While most risk factors are similar for men and women, risk factors may differ in magnitude between the sexes, and recognition of gender-specific risk factors such as gestational diabetes, hypertensive syndromes of pregnancy and polycystic ovarian syndrome provides opportunities for early intervention and prevention. Obesity, hypertension and hyperlipidemia affect both genders; however, women often postpone addressing these risk factors until later in life. The American Heart Association emphasizes that all women are at cardiovascular risk and should maintain a healthy lifestyle and avoid smoking. Blood pressure, hyperlipidemia and diabetes should be aggressively treated. Current available data regarding proposed preventive drug therapies including daily aspirin, HRT, vitamin D and omega-3 fatty acid supplements will be reviewed.

Vitamin D and cardiovascular disease and cancer: not too much and not too little? The need for clinical trials

Low vitamin D levels are more common in women than in men. Low vitamin D levels have been implicated in numerous disease processes including fracture risk, falls, cardiovascular disease, hypertension, diabetes mellitus and cancers. In this article we review recent evidence regarding associations between low vitamin D levels and cancers and cardiovascular disease. We also review evidence regarding associations between high vitamin D levels and vascular calcifications and pancreatic cancer. It appears that there is probably an optimal level of vitamin D that is neither too high nor too low that is required to maximize health. On going clinical trials should aid in elucidating the optimal levels of 25-hydroxyvitamin D for numerous health outcomes.

Vitamin D supplementation and endothelial function in vitamin D deficient HIV-infected patients: a randomized placebo-controlled trial

BACKGROUND

Studies suggest that vitamin D deficiency is a risk factor for cardiovascular disease and diabetes. Vitamin D deficiency is prevalent in HIV patients but the effect of vitamin D supplementation on cardiovascular risk in this population is unknown.

METHODS

We conducted a randomized, double-blind, placebo-controlled trial among 45 HIV-infected adults in Cleveland (OH, USA) on stable antiretroviral therapy with durable virological suppression and a baseline serum 25-hydroxyvitamin D level of ≤20 ng/ml. Participants were randomized 2:1 to vitamin D3 4,000 IU daily or placebo for 12 weeks. The primary outcome was a change in flow-mediated brachial artery dilation (FMD).

RESULTS

Baseline demographics were similar except for age (vitamin D versus placebo, mean ±sd 47 ±8 versus 40 ±10 years; P=0.009). Both groups had reduced FMD at baseline (median values 2.9% [IQR 1.6-4.8] for vitamin D versus 2.5% [IQR 1.7-6.4] for placebo; P=0.819). Despite an increase in the concentration of serum 25-hydroxyvitamin D from baseline to 12 weeks (5.0 ng/ml [IQR -0.9-7.4] versus -1.9 ng/ml [IQR -4.0-0.1] for vitamin D versus placebo, respectively; P=0.003), there was no difference in FMD change (0.55% [IQR -1.05-2.13] versus 0.29% [IQR -1.61-1.77]; P=0.748). Vitamin D supplementation was associated with a decrease in total and non-high-density lipoprotein cholesterol, and an increase in indices of insulin resistance.

CONCLUSIONS

Among HIV-infected individuals with vitamin D deficiency, supplementation with 4,000 IU vitamin D3 daily for 12 weeks modestly improved vitamin D status and cholesterol but worsened insulin resistance without change in endothelial function. The mechanisms of resistance to standard doses of vitamin D and the complex role of vitamin D in glucose metabolism in this population require further investigation.

Is a daily supplementation with 40 microgram vitamin D3 sufficient? A randomised controlled trial

PURPOSE

The effect of 40 μg (1,600 IU) per day of vitamin D(3) on serum 25-hydroxyvitamin D (25(OH)D) and markers of bone and mineral metabolism was evaluated.

METHODS

This intervention study was designed as a double-blind randomised controlled trial. Forty-five community-dwelling subjects (32 females), age 55-84 years, at 58° North latitude were supplemented for 1 year with 40 μg vitamin D(3) plus 1,000 mg calcium per day, or with 1,000 mg calcium per day for controls. Safety parameters and 25(OH)D, intact parathyroid hormone (PTH), ionized calcium, bone-specific alkaline phosphatase (BALP), and tartrate-resistant acid phosphatase isoform 5b (TRACP5b) were measured over the study period.

RESULTS

All subjects supplemented with vitamin D(3) reached a 25(OH)D level above 50 nmol/L. Mean (SD) serum 25(OH)D increased from 50.4 (13.5) nmol/L to 84.2 (17.5) nmol/L, range 55.0-125.0 nmol/L in the vitamin D(3) supplemented group and the corresponding levels for the control group were 47.3 (14.1) nmol/L and 45.7 (13.4) nmol/L, range 26.0-73.0 nmol/L. No serious adverse event was recorded and the highest 25(OH)D level reached, 125.0 nmol/L, is well below toxic levels. BALP and TRACP5b did not change significantly over the study period.

CONCLUSIONS

This trial suggests that a daily supplementation with 40 μg vitamin D(3) is sufficient to secure a 25(OH)D level of 50 nmol/L. No side effects were observed in the study group.