Use of a novel vitamin D bioavailability test demonstrates that vitamin D absorption is decreased in patients with quiescent Crohn's disease

Vitamin D status in relation to Crohn's disease: Meta-analysis of observational studies

OBJECTIVES

Inconsistent findings have been published regarding vitamin D status among patients with Crohn's disease (CD) and the association with disease severity. We aimed to perform a meta-analysis evaluating serum 25-hydroxy vitamin D and 1,25 dehydroxyvitamin D among CD patients compared with healthy and non-healthy controls, the prevalence of vitamin D deficiency, and the association with disease.

METHODS

We searched MEDLINE, SCOPUS, EMBASE, and Google Scholar up to March 2015 for observational studies assessing serum vitamin D levels in CD patients. A total of 63 studies were included in the following four meta-analyses: 1) a meta-analysis on the mean difference of 25(OH)D levels in CD patients compared with healthy (number of studies = 27) and non-healthy (n = 25) controls; 2) a meta-analysis on the mean difference of 1,25(OH)2 D3 levels in CD patients compared with healthy (n = 7) and non-healthy (n = 8) controls; 3) a meta-analysis on the prevalence of vitamin D deficiency (n = 34); 4) a meta-analysis on the correlation coefficients between vitamin D status severity of CD (n = 6). Subgroup analysis and meta-regression were used to discover possible sources of between-study heterogeneity.

RESULTS

It was found that CD patients had lower levels of 25(OH)D compared with healthy (-3.99 ng/mL; 95% confidence interval [CI]: -5.91 to -2.08) but not non-healthy controls (-1.07 ng/mL; 95% CI: -2.84 to 0.70). There was also no significant mean difference for 1,25(OH)2 D3 for both healthy and non-healthy controls. Meta-analysis on the prevalence of vitamin D deficiency showed an overall prevalence of 57.7% (95% CI: 0.502-0.649). An inverse association was observed between serum vitamin D and severity of CD (-0.36; 95% CI: -0.48 to -0.24). Meta-regression showed that mean levels of 25(OH)D were decreased 0.09 for each unit change of latitude among CD patients compared with healthy controls (B = -0.09, P = 0.004, I(2) residual = 86.08%).

CONCLUSIONS

We found that patients with Crohn's disease had lower serum 25(OH)D concentrations compared with their healthy counterparts, and more than half of them have hypovitaminosis D. Moreover, there was an inverse correlation between circulating 25(OH)D concentrations and severity of Crohn's disease.

Association Between Inflammatory Bowel Disease and Vitamin D Deficiency: A Systematic Review and Meta-analysis

BACKGROUND

Vitamin D plays a role in several immune-mediated diseases, but its association with inflammatory bowel disease (IBD) is unclear. We conducted a systematic review and meta-analysis to assess the association between IBD and vitamin D deficiency.

METHODS

We searched electronic databases from inception to December 2014 for observational studies reporting the presence of vitamin D deficiency (defined as serum 25-hydroxycholecalciferol [25(OH)D] level of ≤20 ng/mL) in IBD patients and having a control group without IBD. Odds ratios (ORs) were combined using a random-effects model. Meta-regression was performed using latitude as a moderator. Study quality was assessed using the Newcastle-Ottawa scale.

RESULTS

Out of 816 citations, 14 eligible studies were identified, comprising 1891 participants (938 IBD cases and 953 controls). Meta-analysis showed that patients with IBD had 64% higher odds of vitamin D deficiency when compared with controls (OR = 1.64; 95% confidence interval, 1.30-2.08; I = 7%; P < 0.0001). Patients with ulcerative colitis had more than double the odds of vitamin D deficiency when compared with normal controls (OR = 2.28; 95% confidence interval, 1.18-4.41; I = 41%; P = 0.01). Latitude did not influence the association between IBD and vitamin D deficiency (P = 0.34). Generalizability of our results might be limited as we summarized unadjusted ORs, because of nonavailability of adjusted ORs in individual studies.

CONCLUSIONS

IBD is significantly associated with having higher odds of vitamin D deficiency. Well-designed randomized controlled trials and longitudinal studies are needed to further explain the role of vitamin D in IBD pathogenesis and its therapy.

Common Genetic Variants Influence Circulating Vitamin D Levels in Inflammatory Bowel Diseases

BACKGROUND

The accuracy and utility of electronic health record (EHR)-derived phenotypes in replicating genotype-phenotype relationships have been infrequently examined. Low circulating vitamin D levels are associated with severe outcomes in inflammatory bowel disease (IBD); however, the genetic basis for vitamin D insufficiency in this population has not been examined previously.

METHODS

We compared the accuracy of physician-assigned phenotypes in a large prospective IBD registry to that identified by an EHR algorithm incorporating codified and structured data. Genotyping for IBD risk alleles was performed on the Immunochip and a genetic risk score calculated and compared between EHR-defined patients and those in the registry. Additionally, 4 vitamin D risk alleles were genotyped and serum 25-hydroxy vitamin D [25(OH)D] levels compared across genotypes.

RESULTS

A total of 1131 patients captured by our EHR algorithm were also included in our prospective registry (656 Crohn's disease, 475 ulcerative colitis). The overall genetic risk score for Crohn's disease (P = 0.13) and ulcerative colitis (P = 0.32) was similar between EHR-defined patients and a prospective registry. Three of the 4 vitamin D risk alleles were associated with low vitamin D levels in patients with IBD and contributed an additional 3% of the variance explained. Vitamin D genetic risk score did not predict normalization of vitamin D levels.

CONCLUSIONS

EHR cohorts form valuable data sources for examining genotype-phenotype relationships. Vitamin D risk alleles explain 3% of the variance in vitamin D levels in patients with IBD.

Vitamin D deficiency in patients with intestinal malabsorption syndromes--think in and outside the gut

There is a very high prevalence of vitamin D deficiency, which is defined by a serum level of 25-hydroxyvitamin D [25(OH)D] of lower than 20 ng/mL, in all populations of the world. Unfortunately, the prevalence of vitamin D deficiency in patients with intestinal malabsorption syndromes, including cystic fibrosis (CF), celiac disease (CD), short bowel syndrome and inflammatory bowel disease (IBD), is higher than that in the general population, indicating the presence of disease-specific causative factors. In this review, we aimed to present clinical findings to highlight the roles of insufficient exposure to sunlight and inflammation in the development of vitamin D deficiency in patients with intestinal malabsorption syndromes. Furthermore, we aimed to present experimental evidence that supported a role of vitamin D deficiency in the pathogenesis of IBD. Finally, we reviewed clinical intervention strategies aiming to normalize vitamin D status in and even to improve the conditions of patients and to discuss certain issues that needed to be addressed in future research.

Association of Vitamin D Status and Clinical Outcome in Dogs with a Chronic Enteropathy

Background

Dogs with a chronic enteropathy (CE) have a lower vitamin D status, than do healthy dogs. Vitamin D status has been associated with a negative clinical outcome in humans with inflammatory bowel disease.

Objectives

To examine the relationship between serum 25 hydroxyvitamin D (25(OH)D) concentrations at diagnosis and clinical outcome in dogs with a CE.

Animals

Forty‐one dogs diagnosed with CE admitted to the Royal Dick School of Veterinary Studies, Hospital for Small Animals between 2007 and 2013.

Methods

Retrospective review. Serum 25(OH)D concentrations were compared between dogs which were alive at follow up or had died because of non‐CE‐related reasons (survivors) and dogs which died or were euthanized due to their CE (non‐survivors). A binary logistic regression analysis was performed to determine significant predictors of death in dogs with CE.

Results

Serum concentrations of 25(OH)D at the time a CE was diagnosed were significantly lower in nonsurvivors (n = 15) (median nonsurvivors 4.36 ng/mL, interquartile range 1.6–17.0 ng/mL), median survivors (n = 26) (24.9 ng/mL interquartile range 15.63–39.45 ng/mL, P < .001). Serum 25(OH)D concentration was a significant predictor of death in dogs with CE (odds ratio 1.08 [95% CI 1.02–1.18)]).

Conclusions

Serum 25(OH)D concentrations at diagnosis are predictive of outcome in dogs with CE. The role of vitamin D in the initiation and outcome of chronic enteropathies in dogs is deserving of further study.

Vitamin D and inflammatory bowel disease

Vitamin D deficiency has been recognized as an environmental risk factor for Crohn's disease since the early 80s. Initially, this finding was correlated with metabolic bone disease. Low serum 25-hydroxyvitamin D levels have been repeatedly reported in inflammatory bowel diseases together with a relationship between vitamin D status and disease activity. Subsequently, low serum vitamin D levels have been reported in various immune-related diseases pointing to an immunoregulatory role. Indeed, vitamin D and its receptor (VDR) are known to interact with different players of the immune homeostasis by controlling cell proliferation, antigen receptor signalling, and intestinal barrier function. Moreover, 1,25-dihydroxyvitamin D is implicated in NOD2-mediated expression of defensin-β2, the latter known to play a crucial role in the pathogenesis of Crohn's disease (IBD1 gene), and several genetic variants of the vitamin D receptor have been identified as Crohn's disease candidate susceptibility genes. From animal models we have learned that deletion of the VDR gene was associated with a more severe disease. There is a growing body of evidence concerning the therapeutic role of vitamin D/synthetic vitamin D receptor agonists in clinical and experimental models of inflammatory bowel disease far beyond the role of calcium homeostasis and bone metabolism.

Vitamin D therapy in inflammatory bowel diseases: who, in what form, and how much?

BACKGROUND

The north–south geographical gradient of inflammatory bowel disease (IBD) prevalence, its epidemiology, the genetic association of vitamin D receptor polymorphisms, and results in animal models suggest that vitamin D plays an important role in the pathogenesis of IBD.

AIMS

The purpose of this review was to critically appraise the effectiveness and safety of vitamin D therapy in patients with IBD.

METHODS

MEDLINE, Scopus and Google Scholar were searched from inception to May 20, 2014 using the terms ‘Crohn’s disease’, ‘ulcerative colitis’ and ‘vitamin D’. Results: Vitamin D deficiency is common in patients with IBD. Limited clinical data suggest an association between low vitamin D concentration and increased disease activity in both ulcerative colitis (UC) and Crohn’s disease (CD). To date, only two small open label trials and one randomized controlled trial have shown a positive effect of vitamin D supplementation on disease activity in patients with CD; no effect has been shown for UC. An optimal vitamin D supplementation protocol for patients with IBD remains undetermined, but targeting serum 25-hydroxy vitamin D [25(OH)D] levels between 30 and 50 ng/mL appears safe and may have benefits for IBD disease activity. Depending on baseline vitamin D serum concentration, ileal involvement in CD, body mass index, and perhaps smoking status, daily vitamin D doses between 1800–10,000 international units/day are probably necessary.

CONCLUSION

Increasing preclinical and clinical evidence suggests a role for vitamin D deficiency in the development and severity of IBD. The possible therapeutic role of vitamin D in patients with IBD merits continued investigation.

Optimal vitamin D levels in Crohn's disease: a review

Vitamin D deficiency is common among patients with Crohn's disease. Serum 25-hydroxyvitamin D (25(OH)D) is the best measure of an individual's vitamin D status and current cut-off ranges for sufficiency are debatable. Several factors contribute to vitamin D deficiency in Crohn's disease. These include inadequate exposure to sunlight, inadequate dietary intake, impaired conversion of vitamin D to its active metabolite, increased catabolism, increased excretion and genetic variants in vitamin D hydroxylation and transport. The effects of low 25(OH)D on outcomes other than bone health are understudied in Crohn's disease. The aim of the present review is to discuss the potential roles of vitamin D and the possible levels required to achieve them. Emerging evidence suggests that vitamin D may have roles in innate and adaptive immunity, in the immune-pathogenesis of Crohn's disease, prevention of Crohn's disease-related hospitalisations and surgery, in reducing disease severity and in colon cancer prevention. The present literature appears to suggest that 25(OH)D concentrations of ≥75 nmol/l may be required for non-skeletal effects; however, further research on optimal levels is required.

Vitamin D deficiency in Crohn's disease and healthy controls: a prospective case-control study in the Netherlands

BACKGROUND AND AIMS

Vitamin D deficiency has been observed in a wide range of medical conditions including Crohn's disease (CD). We aimed to assess whether CD patients have lower vitamin D levels than healthy controls, and to determine risk factors for vitamin D deficiency.

METHODS

25(OH)D was measured by chemiluminescent immunoassay in serum obtained from 101 CD patients and 41 controls. Demographics, sunlight exposure, dietary vitamin D intake, comorbidities and medication were recorded using validated questionnaires. In CD patients the Harvey-Bradshaw index, Montreal classification and surgical resections were also evaluated. 25(OH)D levels of > 75 nmol/L, between 50 and 75 nmol/L and < 50 nmol/L were considered as normal, suboptimal and deficient, respectively.

RESULTS

Vitamin D levels were rather low but comparable among CD patients and controls (mean 25(OH)D 51.6 nmol/L(± 26.6) in CD, and 60.8 nmol/L(± 27.6) in controls. Multivariate regression analysis revealed BMI, sun protection behaviour, non-Caucasian ethnicity, no use of tanning beds, and no holidays in the last year as significantly associated with serum 25(OH)D levels in CD patients (R=0.62). In the control group no statistically significant factors were identified that had an impact on 25(OH)D serum levels.

CONCLUSIONS

Vitamin D deficiency is common in CD patients, but also in healthy controls. Appropriate vitamin D screening should be advised in patients with CD. Moreover, the positive effect of sunlight on the vitamin D status should be discussed with CD patients, but this should be balanced against the potential risk of developing melanomas, especially in patients using thiopurines.

Maintenance of optimal vitamin D status in children and adolescents with inflammatory bowel disease: a randomized clinical trial comparing two regimens

CONTEXT

Vitamin D promotes bone health and regulates the immune system, both important actions for pediatric patients with inflammatory bowel disease (IBD). The supplementation dose that would maintain optimal serum 25-hydroxyvitamin D concentration (25OHD ≥ 32 ng/mL) is unknown.

OBJECTIVE

The objective of the study was to compare two supplementation regimens' efficacy and safety in maintaining optimal 25OHD in children with IBD.

DESIGN

This was a randomized, not blinded, controlled trial.

SETTING

The trial was conducted in the Boston Children's Hospital Clinical and Translational Study Unit.

PARTICIPANTS

Sixty-three patients, aged 8-18 years with IBD and baseline 25OHD greater than 20 ng/mL were enrolled; 48 completed the study, and one withdrew for adverse events.

INTERVENTION

Arm A received 400 IU of oral vitamin D2 daily (n = 32). Arm B received 1000 IU daily in the summer/fall and 2000 IU in the winter/spring (n = 31).

MAIN OUTCOME

The main outcome was the probability of maintaining 25OHD of 32 ng/mL or greater in all trimonthly visits for 12 months.

RESULTS

Three participants in arm A (9.4%) and three in arm B (9.7%) achieved the primary outcome (P = .97). The incidence of adverse events, all minor, did not differ. More participants in arm A developed C-reactive protein level of 1 mg/dL or greater (31% vs 10%, P = .04) and IL-6 greater than 3 pg/mL (54% vs 27%, P = .05).

CONCLUSIONS

Daily oral vitamin D2 doses up to 2000 IU were inadequate to maintain optimal 25OHD but were well tolerated. The finding of lower incidence of elevated inflammatory markers and cytokines among participants receiving higher vitamin D2 doses merits further study.

Escherichia coli-host macrophage interactions in the pathogenesis of inflammatory bowel disease

Multiple studies have demonstrated alterations in the intestinal microbial community (termed the microbiome) in Crohn’s disease (CD) and several lines of evidence suggest these changes may have a significant role in disease pathogenesis. In active and quiescent disease, both the faecal and mucosa-associated microbiome are discordant with matched controls with reduced biodiversity, changes in dominant organisms and increased temporal variation described. Mucosa-associated adherent, invasive Escherichia coli (E. coli) (AIEC), pro-inflammatory and resistant to killing by mucosal macrophages, appear to be particularly important. AIEC possess several virulence factors which may confer pathogenic potential in CD. Type-1 pili (FimH) allow adherence to intestinal cells via cell-surface carcinoembryonic antigen-related cell adhesion molecules and possession of long polar fimbrae promotes translocation across the intestinal mucosa via microfold (M)-cells of the follicle-associated epithelium. Resistance to stress genes (htrA, dsbA and hfq) and tolerance of an acidic pH may contribute to survival within the phagolysosomal environment. Here we review the current understanding of the role of mucosa-associated E. coli in Crohn’s pathogenesis, the role of the innate immune system, factors which may contribute to prolonged bacterial survival and therapeutic strategies to target intracellular E. coli.

Vitamin D improves inflammatory bowel disease outcomes: Basic science and clinical review

Vitamin D deficiency is commonly diagnosed among patients with inflammatory bowel disease (IBD). Patients with IBD are at risk of low bone density and increased fractures due to low vitamin D levels, long standing disease, and frequent steroid exposures; as a result, it is well established that vitamin D supplementation in this population is important. There is increasing support for the role of vitamin D in strengthening the innate immune system by acting as an immunomodulator and reducing inflammation in experimental and human IBD. The active form of vitamin D, 1,25(OH)D3, acts on T cells to promote T helper (Th)2/regulatory T responses over Th1/Th17 responses; suppresses dendritic cell inflammatory activity; induces antibacterial activity; and regulates cytokine production in favor of an anti-inflammatory response. Murine and human IBD studies support a therapeutic role of vitamin D in IBD. Risk factors for vitamin D deficiency in this population include decreased sunlight exposure, disease duration, smoking, and genetics. Vitamin D normalization is associated with reduced risk of relapse, reduced risk of IBD-related surgeries, and improvement in quality of life. Vitamin D is an inexpensive supplement which has been shown to improve IBD outcomes. However, further research is required to determine optimal serum vitamin D levels which will achieve beneficial immune effects, and stronger evidence is needed to support the role of vitamin D in inducing disease response and remission, as well as maintaining this improvement in patients’ disease states.

Vitamin D levels and bone metabolism in Chinese adult patients with inflammatory bowel disease

OBJECTIVE

We aimed to investigate the serum 25-hydroxyvitamin D3 (25[OH]D3 ) levels and bone metabolism in adult Chinese patients with inflammatory bowel disease (IBD) and to evaluate the correlation between vitamin D levels and the disease activity as well as the potential risk factors.

METHODS

Age- and gender-matched cohort of IBD patients (124 with ulcerative colitis [UC] and 107 with Crohn's disease [CD]) and 122 healthy controls were enrolled in this study. Serum levels of 25(OH)D3 and bone mineral density (BMD) were measured, and the correlation between the two parameters and the severity of the disease as well as the clinical risk factors were analyzed.

RESULTS

Serum 25(OH)D3 levels were lower in UC (10.32 ± 4.46 ng/mL, P < 0.001) and CD patients (11.57 ± 5.02 ng/mL, P = 0.029) than that in healthy controls (12.87 ± 4.40 ng/mL). 25(OH)D3 levels were negatively correlated with the disease severity of both UC (r = -0.371, P < 0.001) and CD (r = -0.285, P = 0.030). The incidences of osteopenia and osteoporosis were high in the IBD patients (37.9% and 3.2% in UC and 30.8% and 4.7% in CD, respectively). Cumulative quantity of glucocorticoids use was significantly associated with osteopenia and osteoporosis in both UC (odds ratio [OR] 1.219, 95% confidence interval [CI] 1.054-1.410, P = 0.008) and CD patients (OR 1.288, 95% CI 1.033-1.606, P = 0.025).

CONCLUSIONS

Vitamin D deficiency is likely to occur in Chinese patients with IBD and is closely associated with the severity of the disease. Glucocorticoids accumulation is a risk factor for osteopenia and osteoporosis.

Review article: vitamin D and inflammatory bowel diseases

BACKGROUND

Vitamin D is traditionally associated with bone metabolism. The immunological effects of vitamin D have increasingly come into focus.

AIM

To review the evidence supporting a role of vitamin D in inflammatory bowel diseases.

METHODS

A comprehensive search was performed on PubMed using the terms 'crohn's disease' 'ulcerative colitis' and 'vitamin D'.

RESULTS

Vitamin D deficiency is common in patients with inflammatory bowel diseases (IBD) (16-95%) including those with recently diagnosed disease. Evidence supports immunological role of vitamin D in IBD. In animal models, deficiency of vitamin D increases susceptibility to dextran sodium sulphate colitis, while 1,25(OH)2 D3 ameliorates such colitis. One prospective cohort study found low predicted vitamin D levels to be associated with an increased risk of Crohn's disease (CD). Limited data also suggest an association between low vitamin D levels and increased disease activity, particularly in CD. In a large cohort, vitamin D deficiency (<20 ng/mL) was associated with increased risk of surgery (OR 1.8, 95% CI 1.2-2.5) in CD and hospitalisations in both CD (OR 2.1, 95% CI 1.6-2.7) and UC (OR 2.3, 95% CI 1.7-3.1). A single randomised controlled trial demonstrated that vitamin D supplementation may be associated with reduced frequency of relapses in patients with CD compared with placebo (13% vs. 29%, P = 0.06).

CONCLUSIONS

There is growing epidemiological evidence to suggest a role for vitamin D deficiency in the development of IBD and also its influence on disease severity. The possible therapeutic role of vitamin D in patients with IBD merits continued investigation.

Dynamics of vitamin D in patients with mild or inactive inflammatory bowel disease and their families

BACKGROUND

25(OH) vitamin D levels may be low in patients with moderately or severely active inflammatory bowel diseases (IBD: Crohn's disease and Idiopathic Ulcerative Colitis) but this is less clear in patients with mild or inactive IBD. Furthermore there is limited information of any family influence on 25(OH) vitamin D levels in IBD. As a possible risk factor we hypothesize that vitamin D levels may also be low in families of IBD patients.

OBJECTIVES

To evaluate 25[OH] vitamin D levels in patients with IBD in remission or with mild activity. A second objective is to evaluate whether there are relationships within IBD family units of 25[OH] vitamin D and what are the influences associated with these levels.

METHODS

Participants underwent medical history, physical examination and a 114 item diet questionnaire. Serum 25[OH] vitamin D was measured, using a radioimmunoassay kit, (replete ≥ 75, insufficient 50-74, deficient < 25-50, or severely deficient < 25 nmol/L). Associations between 25[OH] vitamin D and twenty variables were evaluated using univariate regression. Multivariable analysis was also applied and intrafamilial dynamics were assessed.

RESULTS

55 patients and 48 controls with their respective families participated (N206). 25[OH] vitamin D levels between patients and controls were similar (71.2 ± 32.8 vs. 68.3 ±26.2 nmol/L). Vitamin D supplements significantly increased intake but correlation with serum 25[OH] vitamin D was significant only during non sunny months among patients. Within family units, patients' families had mean replete levels (82.3 ± 34.2 nmol/L) and a modest correlation emerged during sunny months between patients and family (r2 =0.209 p = 0.032). These relationships were less robust and non significant in controls and their families.

CONCLUSIONS

In patients with mild or inactive IBD 25[OH] vitamin D levels are less than ideal but are similar to controls. Taken together collectively, the results of this study suggest that patient family dynamics may be different in IBD units from that in control family units. However contrary to the hypothesis, intra familial vitamin D dynamics do not pose additional risks for development of IBD.

Vitamin D and Crohn's disease in the adult patient: a review

Crohn's disease (CD) is characterized as a chronic immune-mediated inflammatory disorder of the gastrointestinal tract. Current consensus surrounding the cause of the disease suggests a complex interplay between genetic susceptibility, the intestinal microbiome and environmental factors, leading to the aberrant Th1 and Th17 immune cell mediated response. Vitamin D deficiency is common in CD patients, and long-standing deficiency has been associated with reduced bone mineral density (BMD). Accumulating evidence now suggests that in addition to maintaining skeletal integrity, vitamin D also plays an integral role in regulating the general immune response, a function employed via its genomic actions on the vitamin D receptor (VDR). The VDR is expressed in all immune cells and both directly and indirectly targeted by the bioactive form of vitamin D, 1,25-Dihydroxyvitamin D (1,25[OH]2D). Impaired regulation or deficiency of the vitamin has been linked to the promotion of self-reactive T cell development, loss of immune tolerance to self-structures, and experimental colitis in animal models, whereas the subsequent administration of the vitamin in these models resulted in the improvement of immune-mediated symptoms. In addition, low vitamin D has been associated with disease activity in CD patients, and supplementation appears to be beneficial in improving clinical scores and reducing inflammation. Therefore, the primary aims of this article were to review the molecular evidence supporting the immunoregulatory roles of vitamin D and its supplementation in the CD patient, based on existing literature. The physiological processes, accepted serum concentration values, and its well-recognized role in bone health were also summarized.

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.

Environmental triggers for inflammatory bowel disease

Inflammatory bowel diseases [IBD; Crohn's disease (CD), ulcerative colitis (UC)] are chronic immunologically mediated diseases that are due to a dysregulated immune response to intestinal flora in a genetically susceptible host. Despite advances in genetics, the likelihood of occurrence of disease remains incompletely explained and there appears to be a strong role for the environment in mediating risk of disease. Smoking remains the most widely studied and replicated risk factor, contributing to increased risk and severity of CD while conferring protection against UC. Recent data has suggested novel risk factors. Lower plasma vitamin D is associated with an increased risk of Crohn's disease, and vitamin D supplementation may prevent relapse of disease. Several medications including oral contraceptives, post-menopausal hormone replacement, aspirin, NSAIDs, and antibiotics may increase risk of CD or UC with the mechanisms of effect remaining inadequately defined. There is continuing evidence that depression and psychosocial stress may play a role in the pathogenesis of both CD and UC, while at the same time also increasing risk for disease flares. There is also a growing understanding of the role of diet on IBD, in particular through its effect on the microbiome. Animal protein intake and n-6 fatty acids may increase risk of UC while n-3 fatty acids and dietary fiber may confer protection. The effect of diet on established disease remains poorly studied. There is need for routine measurement of a spectrum of environmental exposures in prospective studies to further our understanding.

Changes in circulating 25-hydroxyvitamin D according to vitamin D binding protein genotypes after vitamin D₃ or D₂supplementation

Background

It is not known whether genetic variation in the vitamin D binding protein (DBP) influences 25-hydroxyvitamin D levels [25(OH)D] after vitamin D supplementation. We aimed to investigate the changes of total 25(OH)D, 25(OH)D₃ and 25(OH)D₂ in a Thai cohort, according to type of vitamin D supplement (vitamin D₃ or D₂) and DBP genotype, after receiving vitamin D₃ or D₂ for 3 months.

Methods

Thirty-nine healthy subjects completed the study. All subjects received 400 IU of either vitamin D₃ or D₂, plus a calcium supplement, every day for 3 months. Total serum 25(OH)D, 25(OH)D₃ and 25(OH)D₂ were measured by LC-MS/MS. Individual genotyping of rs4588 in the DBP gene was performed using real-time PCR.

Results

Vitamin D₃ supplementation of 400 IU/d increased 25(OH)D₃ significantly (+16.2 ± 4.2 nmol/L, p <0.001). Vitamin D₂ (400 IU/d) caused increased 25(OH)D₂ levels (+22.0 ± 2.11 nmol/L, p <0.001), together with a decrease of 25(OH)D₃ (−14.2 ± 2.0 nmol/L, p <0.001). At 3 month, subjects in vitamin D₃ group tended to have higher total 25(OH)D levels than those in vitamin D₂ (67.8 ± 3.9 vs. 61.0 ± 3.0 nmol/L; p = 0.08). Subjects were then classified into two subgroups: homozygous for the DBP rs4588 C allele (CC), and the rest (CA or AA). With D₃ supplementation, subjects with CA or AA alleles had significantly less increase in 25(OH)D₃ and total 25(OH)D when compared with those with the CC allele. However, no difference was found when the supplement was vitamin D₂.

Conclusion

Genetic variation in DBP (rs4588 SNP) influences responsiveness to vitamin D₃ but not vitamin D₂.

Factors associated with vitamin D deficiency in a multicultural inflammatory bowel disease cohort

OBJECTIVE

The aim of this study was to determine the prevalence of vitamin D deficiency in a multicultural inflammatory bowel disease (IBD) cohort and determine predictors of deficiency including ethnicity.

DESIGN

Patients with IBD were recruited into a dedicated database over a 6-month period and evaluated retrospectively.

SETTING

Department of Gastroenterology, St George's University Hospital, London, UK.

OUTCOMES MEASURED

Clinical data including demographics, ethnic group, disease phenotype by the Montreal classification, vitamin D level and season tested were recorded from clinical and electronic medical records. Vitamin D levels were classified as normal (≥50 nmol/l) and deficient (<50 nmol/l).

RESULTS

168 patients had a vitamin D level measured subsequent to diagnosis. There was no significant difference in the median vitamin D level between patients with Crohn's disease (CD) and ulcerative colitis (UC) (39 nmol/l (IQR 23-56) vs 28 nmol/l (IQR 17-51), p=0.35). Overall the median vitamin D level was significantly lower in non-Caucasians (Asian and Black) versus Caucasians (28 nmol/l (IQR 17-41) vs 41 nmol/l (IQR 25-63), p<0.0001). Multiple regression analysis revealed IBD related surgery (OR 2.9) and ethnicity (OR 6.0 non-Caucasian vs Caucasian) in CD and ethnicity (OR 5.0 non-Caucasian vs Caucasian) in UC were independently associated with vitamin D deficiency.

CONCLUSIONS

Vitamin D deficiency is common in IBD patients; therefore, we suggest monitoring of vitamin D levels and correction with supplements especially in non-Caucasians and those with a history of IBD related surgery.

The effect of ultraviolet radiation from a novel portable fluorescent lamp on serum 25-hydroxyvitamin D3 levels in healthy adults with Fitzpatrick skin types II and III

BACKGROUND/PURPOSE

Ultraviolet (UV) B irradiation may provide a safe and effective method to treat vitamin D deficiency. The objective of this study was to assess the effectiveness of a novel Sperti D/UV-Fluorescent lamp in converting 7-dehydrocholesterol (7-DHC) to previtamin D(3) in vitro and in raising serum 25-hydroxyvitamin D(3) [25(OH)D(3) ] in healthy adults.

METHODS

The lamp was assessed in vitro using a 7-DHC solution and a human skin sample. In a prospective cohort study, five healthy adults with skin types II and III were exposed to a 0.75 minimal erythemal dose of UV radiation over ≈ 9% of body surface area three times a week for 4 weeks. The main outcomes were percentage of conversion from 7-DHC to previtamin D(3) in vitro and changes in serum 25(OH)D(3) after irradiation in vivo.

RESULTS

A dose response between UV irradiation time and conversion of 7-DHC to previtamin D(3) was seen in the 7-DHC solution and surgically obtained human skin. The subjects had a significant increase in mean 25(OH)D(3) from 18.4 ± 8.2 to 27.3 ± 7.6 ng/ml (P < 0.001) after 4 weeks of irradiation. No adverse events occurred.

CONCLUSION

The Sperti D/UV-Fluorescent lamp is effective in converting 7-DHC to previtamin D(3) in vitro and in raising serum 25(OH)D(3) in healthy adults.

Review article: vitamin D and inflammatory bowel disease--established concepts and future directions

BACKGROUND

Understanding of the role of vitamin D in health and disease has increased markedly in the past decade, with its involvement extending well beyond traditional roles in calcium and phosphate homeostasis and musculoskeletal health. This conceptual expansion has been underpinned by identification and exploration of components of this axis including vitamin D-binding protein, key enzymes and receptors in multiple cell types, and a greater recognition of nonclassical autocrine and paracrine effects. Its influence in IBD remains uncertain.

AIM

To review the role of vitamin D in bone health, immune regulation and cancer prevention in IBD, and to outline practical issues and limitations of its use.

METHODS

An extensive online literature review including PubMed and Medline.

RESULTS

In patients with IBD, the vitamin D axis provides an important and often underutilised pathway to preserving bone health. Furthermore, an exciting body of clinical and basic science research demonstrates that these pathways may have an integral part to play in regulation of the immune response in IBD, through effects on the intestinal barrier, antigen presenting cells and adaptive T cells. The possibility of chemoprevention requires further study. The optimal target level of 25-hydroxy vitamin D in patients with IBD is currently uncertain, as is the best therapeutic modality.

CONCLUSIONS

Study of vitamin D pathways may result in the development of relatively inexpensive therapeutic options to optimise patient outcomes. Further prospective clinical research is required to address efficacy and long-term safety.

Treatment of vitamin D insufficiency in children and adolescents with inflammatory bowel disease: a randomized clinical trial comparing three regimens

CONTEXT

Vitamin D insufficiency [serum 25-hydroxyvitamin D (25OHD) concentration less than 20 ng/ml] is prevalent among children with inflammatory bowel disease (IBD), and its treatment has not been studied.

OBJECTIVE

The aim of this study was to compare the efficacy and safety of three vitamin D repletion regimens.

DESIGN AND SETTING

We conducted a randomized, controlled clinical trial from November 2007 to June 2010 at the Clinical and Translational Study Unit of Children's Hospital Boston. The study was not blinded to participants and investigators.

PATIENTS

Eligibility criteria included diagnosis of IBD, age 5-21, and serum 25OHD concentration below 20 ng/ml. Seventy-one patients enrolled, 61 completed the trial, and two withdrew due to adverse events.

INTERVENTION

Patients received orally for 6 wk: vitamin D(2), 2,000 IU daily (arm A, control); vitamin D(3), 2,000 IU daily (arm B); vitamin D(2), 50,000 IU weekly (arm C); and an age-appropriate calcium supplement.

MAIN OUTCOME MEASURE

We measured the change in serum 25OHD concentration (Δ25OHD) (ng/ml). Secondary outcomes included change in serum intact PTH concentration (ΔPTH) (pg/ml) and the adverse event occurrence rate.

RESULTS

After 6 wk, Δ25OHD ± se was: 9.3 ± 1.8 (arm A); 16.4 ± 2.0 (arm B); 25.4 ± 2.5 (arm C); P (A vs. C) = 0.0004; P (A vs. B) = 0.03. ΔPTH ± SE was -5.6 ± 5.5 (arm A); -0.1 ± 4.2 (arm B); -4.4 ± 3.9 (arm C); P = 0.57. No participant experienced hypercalcemia or hyperphosphatemia, and the prevalence of hypercalciuria did not differ among arms at follow-up.

CONCLUSIONS

Oral doses of 2,000 IU vitamin D(3) daily and 50,000 IU vitamin D(2) weekly for 6 wk are superior to 2,000 IU vitamin D(2) daily for 6 wk in raising serum 25OHD concentration and are well-tolerated among children and adolescents with IBD. The change in serum PTH concentration did not differ among arms.

Vitamin D supplementation: guidelines and evidence for subclinical deficiency

PURPOSE OF REVIEW

To summarize recommendations from the 2011 US Institute of Medicine report (on vitamin D) and the new guideline from the US Endocrine Society with emphasis on treating and preventing vitamin D deficiency, including patients with inflammatory bowel disease and prior gastric bypass.

RECENT FINDINGS

The US Institute of Medicine Recommended Dietary Allowance of vitamin D is 400 IU per day for children younger than 1 year of age, 600 IU per day for children at least 1 year of age and adults up to 70 years, and 800 IU per day for older adults. The US Institute of Medicine concluded that serum 25-hydroxyvitamin D [25(OH)D] of 20 ng/ml or more will cover the requirements of 97.5% of the population. The US Endocrine Society's Clinical Practice Guideline suggested that 400-1000 IU per day may be needed for children aged less than 1 year, 600-1000 IU per day for children aged 1 year or more, and 1500-2000 IU per day for adults aged 19 years or more to maintain 25(OH)D above the optimal level of 30 ng/ml. Patients with inflammatory bowel disease even in a quiescent state and those with gastric bypass malabsorb vitamin D and need more vitamin D to sustain their vitamin D status.

SUMMARY

Difference in the recommendations from the US Institute of Medicine and the US Endocrine Society's Practice Guideline reflects different goals and views on current evidence. Significant gaps remain in the literature, and studies of vitamin D treatment assessing changes in outcomes at different 25(OH)D levels are needed.

Vitamin D deficiency in Crohn's disease: prevalence, risk factors and supplement use in an outpatient setting

BACKGROUND AND AIMS

Vitamin D deficiency impacts on bone health and has potential new roles in inflammation. We aimed to determine the prevalence of and risk factors for vitamin D deficiency and to explore vitamin D supplement usage in patients with Crohn's disease (CD) in an outpatient setting, compared with controls.

METHODS

Serum 25-hydroxyvitamin D [25(OH)D] concentrations were measured by radioimmunoassay in 151 participants, comprising 81 CD patients and 70 age-, sex- and socio-economic status-matched healthy controls. Levels of 25(OH)D <50 nmol/L were classed as deficient. Data on vitamin supplement usage were recorded for all participants at interview.

RESULTS

Vitamin D deficiency was common in patients with CD (63%) and significantly higher in winter than summer (68% v 50%; p<0.001, χ(2)). Notably, the deficiency rate remained high even in summer (50%). On regression analysis, 25(OH)D levels were inversely associated with winter season. Disease-specific factors for lower serum 25(OH)D levels were longer disease duration and smoking. Overall, 43% of patients reported using a vitamin D-containing supplement, primarily at low dosages (200-400 IU/d); however, this level of supplement did not prevent deficiency. For the majority of CD patients, 25(OH)D remained below optimal levels proposed to confer bone and immune health benefits.

CONCLUSIONS

Vitamin D deficiency was common in patients with CD and associated with longstanding disease, smoking and winter. While over 40% of patients used a vitamin D-containing supplement, the dosages were inadequate to prevent deficiency. Appropriate vitamin D screening and supplementation should be considered in the context of health promotion of outpatients with CD.

Vitamin D status in patients with chronic plaque psoriasis

BACKGROUND

Vitamin D could have important immunomodulatory effects in psoriasis.

OBJECTIVES

To measure 25-hydroxyvitamin D [25(OH)D], parathyroid hormone (PTH) and calcium serum levels in patients with psoriasis and the associations with some relevant clinical features.

METHODS

A cross-sectional study was conducted over 1 year including 145 patients with chronic plaque psoriasis, 112 patients with rheumatoid arthritis (RA) and 141 healthy controls. 25(OH)D, PTH and calcium serum levels were measured in a centralized laboratory. Demography, comorbidities, disease severity and exposure time to sunlight (which was derived by questionnaire) were collected.

RESULTS

The prevalence of vitamin D deficiency [25(OH)D levels <20ngmL(-1) ] in patients with psoriasis was 57·8% vs. 37·5% in patients with RA and 29·7% in healthy controls (P<0·001). In winter, the prevalence of vitamin D deficiency rose to 80·9% in patients with psoriasis, to 41·3% in those with RA and to 30·3% in healthy controls (P<0·001). Patients with psoriasis or psoriatic arthritis did not differ in 25(OH)D serum levels nor in the prevalence of vitamin D deficiency. In the logistic regression analysis, vitamin D deficiency was associated with psoriasis independently of age, sex, body mass index, calcium, PTH levels and season of blood sampling. A limitation is that the study design does not allow a causal or temporal relationship between vitamin D deficiency and psoriasis to be established.

CONCLUSIONS

Vitamin D deficiency may be common in patients with psoriasis, especially in winter.

Probiotics, nuclear receptor signaling, and anti-inflammatory pathways

There is increased investigation of the human microbiome as it relates to health and disease. Dysbiosis is implicated in various clinical conditions including inflammatory bowel disease (IBD). Probiotics have been explored as a potential treatment for IBD and other diseases. The mechanism of action for probiotics has yet to be fully elucidated. This paper discusses novel mechanisms of action for probiotics involving anti-inflammatory signaling pathways. We highlight recent progress in probiotics and nuclear receptor signaling, such as peroxisome-proliferator-activated receptor gamma (PPARγ) and vitamin D receptor (VDR). We also discuss future areas of investigation.