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

Vitamin D deficiency in a European inflammatory bowel disease inception cohort: an Epi-IBD study

BACKGROUND

Serum vitamin D level is commonly low in patients with inflammatory bowel disease (IBD). Although there is a growing body of evidence that links low vitamin D level to certain aspects of IBD such as disease activity and quality of life, data on its prevalence and how it varies across disease phenotype, smoking status and treatment groups are still missing.

MATERIALS AND METHODS

Patients diagnosed with IBD between 2010 and 2011 were recruited. Demographic data and serum vitamin D levels were collected. Variance of vitamin D level was then assessed across different treatment groups, disease phenotype, disease activity and quality of life scores.

RESULTS

A total of 238 (55.9% male) patients were included. Overall, 79% of the patients had either insufficient or deficient levels of vitamin D at diagnosis. Patients needing corticosteroid treatment at 1 year had significantly lower vitamin D levels at diagnosis (median 36.0 nmol/l) (P=0.035). Harvey-Bradshaw Index (P=0.0001) and Simple Clinical Colitis Activity Index scores (P=0.0001) were significantly lower in patients with higher vitamin D level. Serum vitamin D level correlated significantly with SIBQ score (P=0.0001) and with multiple components of SF12. Smokers at diagnosis had the lowest vitamin D levels (vitamin D: 34 nmol/l; P=0.053).

CONCLUSION

This study demonstrates the high prevalence of low vitamin D levels in treatment-naive European IBD populations. Furthermore, it demonstrates the presence of low vitamin D levels in patients with IBD who smoke.

Vitamin D deficiency is associated with disease activity in patients with Crohn's disease

Background/Aims

Previous data suggest that vitamin D has a significant role in inflammatory bowel disease (IBD). We investigated the incidence of vitamin D deficiency in Korean patients with IBD and the correlation between serum vitamin D level and disease activity.

Methods

We retrospectively analyzed the medical records of patients with IBD whose serum vitamin D levels were checked. Deficiency of 25-hydroxyvitamin D was defined as <20 ng/mL. Disease activity was evaluated using the partial Mayo score for ulcerative colitis (≥2 defined as active disease) and Harvey-Bradshaw index for Crohn’s disease (≥4 defined as active disease).

Results

We enrolled 87 patients with IBD (ulcerative colitis [UC], 45; Crohn’s disease [CD], 42). Among them, 65.5% (57/87) were men, with a mean age of 44.9±15.1 years (range, 18–75 years). The mean duration of disease was 4.7±4.8 years (range, 0.1–17.1 years). Vitamin D deficiency was found in 73.6% (64/87) of patients with IBD. Patients with IBD (mean vitamin D level, 16.3±9.0 ng/mL) showed lower vitamin D level than the healthy control group (mean vitamin D level, 20.4±7.0 ng/mL), with no statistically significant difference (P=0.136). Disease activity was inversely correlated with vitamin D deficiency in patients with CD (P=0.007). However, no correlation was observed in patients with UC (P=0.134).

Conclusions

Approximately 75% of Korean patients with IBD showed vitamin D deficiency state. Vitamin D deficiency is associated with disease activity, particularly in patients with CD.

Molecular diagnosis and classification of inflammatory bowel disease

INTRODUCTION

Traditional diagnosis and classification of inflammatory bowel diseases (IBDs) have been based on clinical evaluation, laboratory testing, endoscopy, imaging, and histological examinations. With the advancement of medical technology, an increasing number of molecular surrogates are playing a key role in diagnosis, differential diagnosis, assessment of disease activity, prediction of clinical course, and therapeutic response of IBD. Areas covered: The authors review roles of both existing and emerging surrogates including genetic, serological, histologic, and fecal markers in diagnosis and classification of IBD. Comparisons in advantages and disadvantages of different markers have also been discussed. In addition, this review underscores controversial and unclear aspects which need further study. Expert commentary: IBD is characteristic of chronicity, relapse-remission and destructiveness. It is of great importance for clinicians to make an accurate diagnosis and classification. Current and new molecular markers perform well with acceptable sensitivity and specificity. The use of molecular markers in clinical practice needs to be further explored and then generalized. More work is warranted to identify novel useful markers and elucidate how to apply them together with current markers in clinical settings.

Vitamin D receptor FokI polymorphism and the risks of colorectal cancer, inflammatory bowel disease, and colorectal adenoma

Based on an inverse association between vitamin D levels and the risks of colorectal diseases, a functional start codon polymorphism in the vitamin D receptor (VDR) gene is speculated to affect the risks for these diseases. To validate this hypothesis, we first conducted a case-control study of 695 colorectal cancer patients and 1,397 controls. The association of VDR FokI polymorphism with colorectal cancer risk was analyzed using a logistic regression model. In the present case-control study, compared to the F allele, the f allele seemed to be associated with lower risks of colon cancer and advanced colorectal cancer. Additionally, a meta-analysis of 27 studies was conducted to combine findings from previous studies investigating the association of FokI polymorphism with colorectal disease using a random effects model. In the present meta-analysis, the f allele was positively associated with the risk of inflammatory bowel disease, including Crohn’s disease and ulcerative colitis. However, this allele was inversely associated with colon cancer and was not associated with the risk of rectal cancer or colorectal adenoma. In conclusion, the findings from this study imply that the role of VDR FokI polymorphism may differ based on the type and severity of colorectal disease.

Fatigue is not associated with vitamin D deficiency in inflammatory bowel disease patients

AIM

To investigate if vitamin D deficiency is associated with fatigue in patients with inflammatory bowel disease (IBD).

METHODS

IBD patients were recruited from nine hospitals in the southeastern and western regions of Norway to participate in a multicenter cross-sectional study lasting from March 2013 to April 2014. Data were collected by interviews, from medical records and laboratory tests. The Fatigue Questionnaire (FQ) was used to measure fatigue. Linear and logistic regression models were applied to explore the possible association between vitamin D deficiency and total fatigue scores and chronic fatigue, respectively. The analyses were adjusted for age, gender, disease activity, depressive symptoms and sleep disturbance.

RESULTS

In total, 405 patients were included in the analyses, of which 227 (56%) had Crohn’s disease (CD) and 178 (44%) had ulcerative colitis (UC). Vitamin D deficiency (< 50 nmol/L) was present in half (203/405) of the patients. Chronic fatigue was reported by 116 (29%) of all included patients with substantial fatigue reported by 194 (48%). Vitamin D levels were neither associated with total fatigue nor with chronic fatigue. Higher total fatigue scores and chronic fatigue were both associated with increased disease activity scores in patients with UC and CD, but not with increased CRP or fecal calprotectin. In UC patients, female gender was associated with fatigue in the univariate analysis, but no such difference was found when adjusted for elevated disease activity scores. Sleep disturbance and more depressive symptoms were associated with total fatigue scores in both UC and CD patients, but with chronic fatigue only in CD patients.

CONCLUSION

In this study, no significant association between fatigue and vitamin D deficiency in IBD patients was revealed.

High Prevalence of Vitamin D Deficiency among Patients with Inflammatory Bowel Disease

Background

Vitamin D is a hormone with immunomodulatory properties. Vitamin D deficiency has been reported for patients with inflammatory bowel disease (IBD). In this cross-sectional study, 25-hydroxyvitamin D3 (25-OH-D3) levels in patients with IBD were compared to those in patients with irritable bowel syndrome (IBS).

Methods

A total of 181 patients, 156 with IBD and 25 with IBS, were included. The influence of disease activity, inflammatory markers, physical activity, and season were assessed.

Results

A total of 58.6$ (n = 58) of the patients with Crohn's disease (CD) and 44.6$ (n = 25) of the patients with ulcerative colitis (UC) had a 25-OH-D3 level < 50 nmol/L. CD patients showed significantly decreased 25-OH-D3 levels compared to the IBS patients (p = 0.018), but no significant difference was found for UC patients. In a linear regression model adjusted for age, gender, and BMI, a significant inverse association of C-reactive protein (CRP) (p = 0.031) and faecal calprotectin (FC) (p = 0.025) with 25-OH-D3 levels was observed for CD patients. Seasonal variation in 25-OH-D3 levels was found in CD patients, with significantly lower values in spring than in summer (p = 0.04).

Conclusion

Vitamin D deficiency was common in all IBD patients, but more pronounced in CD patients, in whom it also showed a significant inverse association with inflammatory markers such as CRP and FC.

Role of Vitamin D in the Natural History of Inflammatory Bowel Disease

Inflammatory bowel disease [IBD], including ulcerative colitis and Crohn's disease, is a chronic and unpredictable condition characterised by alternating periods of remission interspersed with relapses. In recent years, accumulating support for an immunomodulating effect of vitamin D on both the innate and the adaptive immune systems has been presented. Through the vitamin D receptor, the active form of vitamin D, 1,25[OH]2D, induces antimicrobial peptide secretion, decreases dendritic cell activity, and promotes Th2 and regulatory T cell development and activity. In addition, vitamin D promotes an increased ratio of anti-inflammatory cytokines to pro-inflammatory cytokines. Studies in IBD point to a role for vitamin D in ameliorating disease outcome. Suboptimal circulating levels of 25-hydroxyvitamin D are common in IBD and appear to be associated with an increased risk of flares, IBD-related hospitalisations and surgeries, an inadequate response to tumour necrosis factor [TNF] inhibitors, a deterioration in quality of life, and low bone mineral density. With only few available randomised double-blind, placebo-controlled studies investigating therapeutic effects of vitamin D related to IBD, further research is necessary to determine the true therapeutic potential of vitamin D, as well as to define its optimal range in serum to achieve and maintain quiescence of disease. This review aims to summarise the latest knowledge on the extraskeletal effects of vitamin D in IBD, and outlines the potential deleterious consequences of vitamin D deficiency in this patient cohort.

Vitamin D Deficiency in a Portuguese Cohort of Patients with Inflammatory Bowel Disease: Prevalence and Relation to Disease Activity

Background and Aims

Vitamin D deficiency is more common in inflammatory bowel disease (IBD) patients than in the general population. However, there are conflicting data about predictive factors of vitamin D deficiency and its potential association with disease activity. The aims of this study were to determine the prevalence and predictive factors of vitamin D deficiency and to evaluate a possible association with disease activity.

Methods

A prospective observational study was conducted, including patients with IBD from January to July 2016. The Endocrine Society guidelines were considered for defining levels of serum 25-hydroxyvitamin D (25-OH-D) as follows: deficient (< 20 ng/mL, < 10 ng/mL being severe deficiency), insufficient (21-29 ng/mL), and adequate (> 30 ng/mL).

Results

A total of 152 patients (52% men; 47.2 ± 17.3 years) were included, of whom 70% had Crohn's disease (CD). Thirty-seven percent of patients were on immunosuppressors and 17% were on biologics. The majority were outpatients (88.2%). Mean 25-OH-D levels were 17.1 ± 8 ng/mL (CD: 16.7 ± 8 ng/mL vs. ulcerative colitis: 17.6 ± 7 ng/mL, p = 0.1). Inadequate levels were present in 90.8% of patients (deficiency: 68.4%; insufficiency: 22.4%). A significant negative correlation between 25-OH-D levels and age (r = -0.2, p = 0.04), C-reactive protein (CRP) levels (r = -0.22, p = 0.004), and Harvey-Bradshaw index (HBi) (r = -0.32, p = 0.001) was found. Patients with severe deficiency showed a higher CRP (0.6 vs. 1.4 mg/dL, p = 0.03), erythrocyte sedimentation rate (ESR) (22 vs. 31 mm/h, p = 0.03), and HBi (2 vs. 5, p < 0.001) and lower hemoglobin (13.6 vs. 12.7 g/dL, p = 0.02). There was no association between vitamin D deficiency and gender, type, extent, and duration of disease, surgery, and other measures of disease activity, such as ESR, hemoglobin (these 2 items except for severe deficiency), fecal calprotectin, or Truelove and Witts classification.

Conclusions

There is a high prevalence of inadequate levels of vitamin D in IBD patients, particularly deficiency (68.4%). There seems to exist an association between lower levels of vitamin D and higher disease activity, especially in CD.

Current, experimental, and future treatments in inflammatory bowel disease: a clinical review

Inflammatory bowel diseases (IBDs) may result from dysregulated mucosal immune responses directed toward the resident intestinal microbiota. This review describes the hallmark immunobiology of Crohn's disease and ulcerative colitis as well as therapeutic targets and mechanisms of action for current, experimental, and future treatments in IBD. Conventional therapies include 5-aminosalicylic acid, glucocorticosteroids, thiopurines, and methotrexate. Since 1997, monoclonal antibodies have gained widespread use. These consist of antibodies directed against pro-inflammatory cytokines such as tumor necrosis factor α, interleukin (IL)-12, and IL-23, or anti-homing antibodies directed against α4β7 integrin. Emerging oral therapies include modulators of intracellular signal transduction such as Janus kinase inhibitors. Vitamin D may help to regulate innate and adaptive immune responses. Modulation of the intestinal microbiota, using live microorganisms (probiotics), substrates for the colonic microbiota (prebiotics), or fecal microbiota transplantation (FMT), is in development. Dietary supplements are in widespread use, but providing evidence for their benefit is challenging. Stem cell treatment and nervous stimulation are promising future treatments.

Vitamin D in pediatric age: consensus of the Italian Pediatric Society and the Italian Society of Preventive and Social Pediatrics, jointly with the Italian Federation of Pediatricians

Vitamin D plays a pivotal role in the regulation of calcium-phosphorus metabolism, particularly during pediatric age when nutritional rickets and impaired bone mass acquisition may occur.Besides its historical skeletal functions, in the last years it has been demonstrated that vitamin D directly or indirectly regulates up to 1250 genes, playing so-called extraskeletal actions. Indeed, recent data suggest a possible role of vitamin D in the pathogenesis of several pathological conditions, including infectious, allergic and autoimmune diseases. Thus, vitamin D deficiency may affect not only musculoskeletal health but also a potentially wide range of acute and chronic conditions. At present, the prevalence of vitamin D deficiency is high in Italian children and adolescents, and national recommendations on vitamin D supplementation during pediatric age are lacking. An expert panel of the Italian Society of Preventive and Social Pediatrics reviewed available literature focusing on randomized controlled trials of vitamin D supplementation to provide a practical approach to vitamin D supplementation for infants, children and adolescents.

Nutrition in Pediatric Inflammatory Bowel Disease: A Position Paper on Behalf of the Porto Inflammatory Bowel Disease Group of the European Society of Pediatric Gastroenterology, Hepatology and Nutrition

BACKGROUND AND AIMS

A growing body of evidence supports the need for detailed attention to nutrition and diet in children with inflammatory bowel disease (IBD). We aimed to define the steps in instituting dietary or nutritional management in light of the current evidence and to offer a useful and practical guide to physicians and dieticians involved in the care of pediatric IBD patients.

METHODS

A group of 20 experts in pediatric IBD participated in an iterative consensus process including 2 face-to-face meetings, following an open call to Nutrition Committee of the European Society of Pediatric Gastroenterology, Hepatology and Nutrition Porto, IBD Interest, and Nutrition Committee. A list of 41 predefined questions was addressed by working subgroups based on a systematic review of the literature.

RESULTS

A total of 53 formal recommendations and 47 practice points were endorsed with a consensus rate of at least 80% on the following topics: nutritional assessment; macronutrients needs; trace elements, minerals, and vitamins; nutrition as a primary therapy of pediatric IBD; probiotics and prebiotics; specific dietary restrictions; and dietary compounds and the risk of IBD.

CONCLUSIONS

This position paper represents a useful guide to help the clinicians in the management of nutrition issues in children with IBD.

Vitamin D deficiency in childhood: old lessons and current challenges

Hypovitaminosis D in childhood is a re-emerging public health problem in developed countries. New life style habits, current "epidemics" of obesity in children and adolescents worldwide, and other preventable risk factors may play a role in favoring the occurrence of vitamin D deficiency. In addition to skeletal consequences, hypovitaminosis D has been found to be involved in the development of serious health extra-skeletal problems in childhood, including atopy and autoimmunity. The increasing concerns about the global health impact of vitamin D deficiency make further research necessary to fill the gaps of knowledge in this field, and particularly to establish universally accepted "normal" serum 25(OH)D levels in the pediatric population, and to improve strategies for the screening, prevention and treatment of hypovitaminosis D. This review discusses the key points of hypovitaminosis D in childhood in the light of new knowledge, and highlights the limitations of current strategies to control this condition.

The effect of vitamin D supplementation on thyroid autoantibody levels in the treatment of autoimmune thyroiditis: a systematic review and a meta-analysis

PURPOSE

Although observational studies suggested that vitamin D plays a role in autoimmune thyroiditis (AIT), intervention trials yielded inconsistent findings. We therefore conducted a systematic review and a meta-analysis to evaluate the effects of Vitamin D on decreasing autoantibodies in patients with AIT.

METHOD

We identified all studies that assessed the changes of TPO-Ab and Tg-Ab in patients with AIT under the treatment of vitamin D from PubMed, Embase, The Cochrane Library, Chinese National Knowledge Infrastructure, Wanfang, and VIP Database.

RESULTS

Six randomized controlled trials (RCTs) were included in this systematic review representing a total of 344 patients with AIT. The results showed that Vitamin D supplementation significantly dropped TPO-Ab titers [three studies, random effects standardized mean difference (SMD): -1.11, 95% CI -1.52 to -0.70, P < 0.01] at six months, but not at no more than 3 months [random effects SMD: -0.12, 95% CI: -0.69 to 0.44, P = 0.67]. As compared with control group, participants who received vitamin D supplementation demonstrated significantly lower Tg-Ab [random effects SMD: -0.55, 95% CI: -1.05 to -0.04, P = 0.033]. In addition, no serious adverse effect was reported.

CONCLUSIONS

The current evidence suggests that vitamin D supplementation could decrease serum TPO-Ab and Tg-Ab titers of patients with AIT in the short-term (about six months). More high quality studies are needed to further confirm the effects, especially the long-term effects of Vitamin D supplementation on thyroid autoantibodies levels in the treatment of AIT.

Vitamins and Minerals in Inflammatory Bowel Disease

Indiscriminate use of multivitamin/mineral supplements in the general population may be misguided, but patients with chronic Inflammatory Bowel Diseases (IBD) should be monitored and compensated for nutritional deficiencies. Mechanistic links between vitamin/mineral deficiencies and IBD pathology has been found for some micronutrients and normalizing their levels is clinically beneficial. Others, like vitamin A, although instinctively desirable, produced disappointing results. Restoring normal levels of the selected micronutrients requires elevated doses to compensate for defects in absorptive or signaling mechanisms. This article describes some aspects of vitamin and mineral deficiencies in IBD, and summarizes pros and cons of supplementation.

Vitamin D Deficiency Is Associated with Endoscopic Severity in Patients with Crohn's Disease

Background and Aims

Vitamin D deficiency is common in patients with Crohn's disease and is associated with disease activity. Relationship between vitamin D and endoscopic disease activity is unknown. The aim of the study is to determine the association between vitamin D status and endoscopic disease activity in CD patients.

Methods

Consecutive hospitalized CD patients from 2014 to 2016 who received vitamin D assessment and colonoscopy were retrospectively evaluated. Clinical disease activity was assessed by Crohn's disease activity index and C-reactive protein. Endoscopic activity was calculated using simple endoscopic score for Crohn's disease.

Results

Median serum 25OHD level of 131 patients was lower than healthy controls [21.1 nmol/L (11.8–32.3) versus 49.9 nmol/L (44.9–57.4), P = 0.007]. 125 (95%) patients had vitamin D deficiency and the rest (5%) had vitamin D insufficiency. Serum 25OHD was inversely correlated with CRP (r = −0.308, P < 0.001), CDAI (r = −0.582, P < 0.001), SES-CD (r = −0.294, P = 0.001), and endoscopic severity stratified by SES-CD (P = 0.001).

Conclusion

Vitamin D deficiency was prevalent among hospitalized CD patients. Vitamin D levels were inversely correlated with endoscopic disease activity. Vitamin D status could be a biomarker in assessing disease activity among hospitalized CD patients in addition to CDAI and CRP.

Hormonal vitamin D up-regulates tissue-specific PD-L1 and PD-L2 surface glycoprotein expression in humans but not mice

PD-L1 (programmed death ligand 1) and PD-L2 are cell-surface glycoproteins that interact with programmed death 1 (PD-1) on T cells to attenuate inflammation. PD-1 signaling has attracted intense interest for its role in a pathophysiological context: suppression of anti-tumor immunity. Similarly, vitamin D signaling has been increasingly investigated for its non-classical actions in stimulation of innate immunity and suppression of inflammatory responses. Here, we show that hormonal 1,25-dihydroxyvitamin D (1,25D) is a direct transcriptional inducer of the human genes encoding PD-L1 and PD-L2 through the vitamin D receptor, a ligand-regulated transcription factor. 1,25D stimulated transcription of the gene encoding PD-L1 in epithelial and myeloid cells, whereas the gene encoding the more tissue-restricted PD-L2 was regulated only in myeloid cells. We identified and characterized vitamin D response elements (VDREs) located in both genes and showed that 1,25D treatment induces cell-surface expression of PD-L1 in epithelial and myeloid cells. In co-culture experiments with primary human T cells, epithelial cells pretreated with 1,25D suppressed activation of CD4⁺ and CD8⁺ cells and inhibited inflammatory cytokine production in a manner that was abrogated by anti-PD-L1 blocking antibody. Consistent with previous observations of species-specific regulation of immunity by vitamin D, the VDREs are present in primate genes, but neither the VDREs nor the regulation by 1,25D is present in mice. These findings reinforce the physiological role of 1,25D in controlling inflammatory immune responses but may represent a double-edged sword, as they suggest that elevated vitamin D signaling in humans could suppress anti-tumor immunity.

Vitamin D downregulates the IL-23 receptor pathway in human mucosal group 3 innate lymphoid cells

BACKGROUND

Vitamin D deficiency is a risk factor for inflammatory bowel disease (IBD). The IL-23-driven tissue-resident group 3 innate lymphoid cells (ILC3s) play essential roles in intestinal immunity, and targeting IL-23/12 is a promising approach in IBD therapy.

OBJECTIVE

We set out to define the role of 1α,25-dihydroxy vitamin D3 (1,25D) in regulating functional responses of human mucosal ILC3s to IL-23 plus IL-1β stimulation.

METHODS

Transcriptomes of sorted tonsillar ILC3s were assessed by using microarray analysis. ILC3 cytokine production, proliferation, and differentiation were determined by means of flow cytometry, ELISA, and multiplex immunoassay. Intestinal cell suspensions and ILC3s sorted from gut biopsy specimens of patients with IBD were also analyzed along with plasma 25-hydroxy vitamin D3 (25D) detection.

RESULTS

ILC3s stimulated with IL-23 plus IL-1β upregulated the vitamin D receptor and responded to 1,25D with downregulation of the IL-23 receptor pathway. Consequently, 1,25D suppressed IL-22, IL-17F, and GM-CSF production from tonsillar and gut ILC3s. In parallel, 1,25D upregulated genes linked to the IL-1β signaling pathway, as well as the IL-1β-inducible cytokines IL-6, IL-8, and macrophage inflammatory protein 1α/β. The 1,25D-triggered skewing in ILC3 function was not accompanied or caused by changes in viability, proliferation, or phenotype. Finally, we confirmed low 25D plasma levels in patients with IBD with active inflammation.

CONCLUSION

In light of the beneficial targeting of IL-23/12 in patients with IBD, 1,25D appears as an interesting therapeutic agent that inhibits the IL-23 receptor pathway, providing a novel mechanism for how ILC3s could be manipulated to regulate intestinal inflammation.

Impact of vitamin D on the hospitalization rate of Crohn's disease patients seen at a tertiary care center

AIM

To study the association between vitamin D level and hospitalization rate in Crohn’s disease (CD) patients.

METHODS

We designed a retrospective cohort study using adult patients (> 19 years) with CD followed for at least one year at our inflammatory bowel disease center. Vitamin D levels were divided into: low mean vitamin D level (< 30 ng/mL) vs appropriate mean vitamin D level (30-100 ng/mL). Generalized Poisson Regression Models (GPR) for Rate Data were used to estimate partially adjusted and fully adjusted incidence rate ratios (IRR) of hospitalization among CD patients. We also examined IRRs for vitamin D level as a continuous variable.

RESULTS

Of the 880 CD patients, 196 patients with vitamin D level during the observation period were included. Partially adjusted model demonstrated that CD patients with a low mean vitamin D level were almost twice more likely to be admitted (IRR = 1.76, 95%CI: 1.38-2.24) compared to those with an appropriate vitamin D level. The fully adjusted model confirmed this association (IRR = 1.44, 95%CI: 1.11-1.87). Partially adjusted model with vitamin D level as a continuous variable demonstrated, higher mean vitamin D level was associated with a 3% lower likelihood of admission with every unit (ng/mL) rise in mean vitamin D level (IRR = 0.97, 95%CI: 0.96-0.98). The fully adjusted model confirmed this association (IRR = 0.98, 95%CI: 0.97-0.99).

CONCLUSION

Normal or adequate vitamin D stores may be protective in the clinical course of CD. However, this role needs to be further characterized and understood.

Supplementation with 2000 IU of Cholecalciferol Is Associated with Improvement of Trabecular Bone Mineral Density and Muscle Power in Pediatric Patients with IBD

BACKGROUND

Inflammatory bowel diseases (IBD) are associated with altered bone health and increased risk for fractures. Vitamin D deficiency is frequently found in IBD; however, the effect of vitamin D supplementation on bone health of children with IBD is poorly understood. We aimed to observe the changes in volumetric bone density and dynamic muscle functions after vitamin D substitution in a cohort of pediatric patients with IBD.

METHODS

This was a prospective observational study of 55 patients (aged 5-19 years) with IBD. Bone quality was assessed using peripheral quantitative computed tomography and muscle functions by jumping mechanography at baseline and after a median of 13.8 (interquartile range, 12.0-16.0) months of daily substitution of 2000 IU of cholecalciferol.

RESULTS

Median serum levels of 25-hydroxyvitamin D increased from 58 nmol/L at the baseline visit to 85 nmol/L at the last follow-up visit (P < 0.001); no signs of overdose were reported. The Z-scores of trabecular bone mineral density, cortical bone cross-sectional area, and maximal muscle power improved significantly during the follow-up period (+0.5, P = 0.001, +0.3, P = 0.002 and +0.5, P = 0.002, respectively). Cholecalciferol substitution was positively associated with trabecular bone mineral density and maximal muscle power (estimates 0.26, 95% confidence interval 0.14-0.37, P < 0.0001 and 0.60, 95% confidence interval 0.32-0.85, P < 0.0001, respectively) but not with the Strength-Strain Index or maximal muscle force (Fmax).

CONCLUSIONS

We observed an improvement in bone and muscle parameters after cholecalciferol substitution in pediatric patients with IBD. Therefore, vitamin D substitution can be considered in such patients.

Vitamin D in Autoimmunity: Molecular Mechanisms and Therapeutic Potential

Over the last three decades, it has become clear that the role of vitamin D goes beyond the regulation of calcium homeostasis and bone health. An important extraskeletal effect of vitamin D is the modulation of the immune system. In the context of autoimmune diseases, this is illustrated by correlations of vitamin D status and genetic polymorphisms in the vitamin D receptor with the incidence and severity of the disease. These correlations warrant investigation into the potential use of vitamin D in the treatment of patients with autoimmune diseases. In recent years, several clinical trials have been performed to investigate the therapeutic value of vitamin D in multiple sclerosis, rheumatoid arthritis, Crohn’s disease, type I diabetes, and systemic lupus erythematosus. Additionally, a second angle of investigation has focused on unraveling the molecular pathways used by vitamin D in order to find new potential therapeutic targets. This review will not only provide an overview of the clinical trials that have been performed but also discuss the current knowledge about the molecular mechanisms underlying the immunomodulatory effects of vitamin D and how these advances can be used in the treatment of autoimmune diseases.

Vitamin D deficiency in inflammatory bowel disease: prevalence and predictors in a Norwegian outpatient population

BACKGROUND AND AIM

Vitamin D deficiency is common in inflammatory bowel disease (IBD). The aims of the present study were to determine the prevalence of vitamin D deficiency and to identify clinical and epidemiological variables associated with vitamin D deficiency in an outpatient population with IBD.

METHODS

Participants were recruited from nine hospitals in the southeastern and western regions of Norway as part of an observational, multicentre study from March 2013 to April 2014. Clinical and epidemiological data were collected by interview and from medical records. All analyses of serum 25-hydroxyvitamin D (25-OH-D) were performed in the same laboratory.

RESULTS

In total, 49% (200/408) of the patients had a 25-OH-D concentration <50 nmol/L, including 53% (122/230) of the Crohn's disease (CD) patients and 44% (78/178) of the ulcerative colitis (UC) patients. In CD patients, disease activity, measured as the HBI, was inversely associated with vitamin D deficiency. No such association was observed with the Simple Clinical Colitis Activity Index (SCCAI) scores in UC, but in UC patients, vitamin D deficiency was associated with elevated faecal calprotectin >100 mg/kg. In patients with CD, there were significantly more relapses during the previous year in patients with vitamin D deficiency.

CONCLUSIONS

Vitamin D deficiency was common, especially in CD, and was associated with increased disease activity, a relapsing disease course and higher inflammatory activity.

Feeding the microbiota-gut-brain axis: diet, microbiome, and neuropsychiatry

The microbial population residing within the human gut represents one of the most densely populated microbial niche in the human body with growing evidence showing it playing a key role in the regulation of behavior and brain function. The bidirectional communication between the gut microbiota and the brain, the microbiota-gut-brain axis, occurs through various pathways including the vagus nerve, the immune system, neuroendocrine pathways, and bacteria-derived metabolites. This axis has been shown to influence neurotransmission and the behavior that are often associated with neuropsychiatric conditions. Therefore, research targeting the modulation of this gut microbiota as a novel therapy for the treatment of various neuropsychiatric conditions is gaining interest. Numerous factors have been highlighted to influence gut microbiota composition, including genetics, health status, mode of birth, and environment. However, it is diet composition and nutritional status that has repeatedly been shown to be one of the most critical modifiable factors regulating the gut microbiota at different time points across the lifespan and under various health conditions. Thus the microbiota is poised to play a key role in nutritional interventions for maintaining brain health.