Prediagnostic Serum Vitamin D Levels and the Risk of Crohn's Disease and Ulcerative Colitis in European Populations: A Nested Case-Control Study

Role of diet in prevention versus treatment of Crohn's disease and ulcerative colitis

Diet is a modifiable risk factor for disease course and data over the past decade have emerged to indicate its role in Crohn's disease (CD) and ulcerative colitis (UC). However, literature is riddled with misinterpretation of data, often leading to unexpected or conflicting results. The key understanding is that causative factors in disease development do not always proceed to an opportunity to change disease course, once established. Here, we discuss the data on dietary influences in three distinct disease states for CD and UC-predisease, active disease and quiescent disease. We appraise the literature for how our dietary recommendations should be shaped to prevent disease development and if or how that differs for CD and UC induction therapy and maintenance therapy. In UC, principles of healthy eating are likely to play a role in all states of disease. Conversely, data linking dietary factors to CD prevention and treatment are paradoxical with the highest quality evidence for CD treatment being exclusive enteral nutrition, a lactose, gluten and fibre-free diet comprising solely of ultraprocessed food-all dietary factors that are not associated or inversely associated with CD prevention. High-quality evidence from dietary trials is much awaited to expand our understanding and ultimately lead our dietary recommendations for targeted patient populations.

The correlation between serum 25-hydroxyvitamin D level and ulcerative colitis: a systematic review and meta-analysis

OBJECTIVE

The incidence of UC has increased yearly. Many studies have suggested that patients with ulcerative colitis have abnormal vitamin D levels. A systematic review and meta-analysis were conducted to investigate the association between vitamin D levels and ulcerative colitis.

METHODS

We searched PubMed, Embase, Cochrane Library, China National Knowledge Infrastructure, Wanfang and China Science and Technology Journal Database (VIP) from inception to December 2022. We included case-control studies comparing the differences in vitamin D levels between patients with ulcerative colitis and healthy populations. Meta-analysis was performed using Review Manager5.4, Stata17.0 and other software.

RESULTS

Sixteen eligible observational studies were selected from 473 articles involving 2234 subjects, and they included 987 patients with ulcerative colitis and 1247 controls. The results showed that the serum level of vitamin D in patients with ulcerative colitis was significantly lower than that in healthy controls (SMD = -0.83, 95% CI: -1.18, -0.48). Vitamin D deficiency was reported in five studies. The prevalence of vitamin D deficiency was significantly higher in the ulcerative colitis group than in the healthy control group (OR = 1.90, 95% CI: 1.38, 2.62).

CONCLUSION

Serum vitamin D levels were significantly lower in patients with ulcerative colitis than in healthy controls.

The Role of Vitamin D in Patients with Inflammatory Bowel Disease Treated with Vedolizumab

BACKGROUND

Many clinical factors can contribute to the efficacy of medical therapy in Inflammatory Bowel Disease (IBD). We assessed their effects on the efficacy of vedolizumab therapy in a cohort of patients with IBD.

METHODS

We conducted a retrospective study on patients between 18 and 80 years of age with ulcerative colitis (UC) or Crohn's disease (CD) who were seen in the IBD program at Houston Methodist in Houston, TX and treated with vedolizumab for at least 6 months from 2018 to 2022. We investigated factors prior to the initiation of therapy that best predicted treatment response, with an emphasis on vitamin D levels and examined several variables including patients' demographics and clinical information on disease location and severity and nutritional status before and after the initiation of vedolizumab. Post-treatment data were gathered after a minimum of 6 months of vedolizumab therapy. The clinical parameters used for the study were the Harvey-Bradshaw Index for CD and the Activity Index for UC.

RESULTS

There were 88 patients included in our study of whom 44 had CD and 44 had UC.; median age was 39.5 (31.0, 53.25) years; 34% patients were male; and 80.7% were Caucasian. All patients received an induction dosing of 300 mg vedolizumab at 0, 2, and 6 weeks then maintenance dosing as standard of care every 8 weeks. Among UC patients with vitamin D ≥ 30 ng/mL at the initiation of vedolizumab therapy, UC Endoscopic Index of Severity (UCEIS) scores after 6 months of therapy were significantly lower than in those who had low pre-treatment vitamin D levels (1.5 vs. 3.87, p = 0.037). After treatment, vitamin D levels improved more significantly in the higher pre-treatment vitamin D group, with a median level of 56 ng/mL, than in the lower pre-treatment vitamin D group, with a median level of only 31 ng/mL (p = 0.007). In patients with CD with vitamin D ≥ 30 ng/mL at the initiation of vedolizumab therapy, we found higher iron saturation (12 vs. 25%, p = 0.008) and higher vitamin B12 levels (433.5 vs. 885 pg/mL, p = 0.003) than in those with vitamin D < 30 ng/mL. After treatment, CD patients with high pre-treatment vitamin D levels had significantly higher vedolizumab levels (27.35 vs. 14.35 μg/mL, p = 0.045) than those with low pre-treatment vitamin D. Post-treatment scores and inflammatory markers in CD patients (HBI, CRP, ESR, and SES-CD) were lower in those who had lower baseline vitamin D.

CONCLUSIONS

Our results show higher pre-treatment vitamin D levels predicted significant endoscopic improvement in patients with ulcerative colitis (UC). Improving vitamin D levels lowered C-reactive protein levels significantly in CD patients. Higher vitamin D levels were seen after treatment in both UC and CD patients. Vitamin D can play a role in clinical and endoscopic outcomes and should be assessed routinely and optimized in patients with IBD.

Pretreatment Vitamin D Concentrations Do Not Predict Therapeutic Outcome to Anti-TNF Therapies in Biologic-Naïve Patients With Active Luminal Crohn's Disease

Background and Aims

Vitamin D has a regulatory role in innate and adaptive immune processes. Previous studies have reported that low pretreatment vitamin D concentrations are associated with primary non-response (PNR) and non-remission to anti-TNF therapy. This study aimed to assess whether pretreatment 25-hydroxyvitamin D concentrations predicted PNR and non-remission to infliximab and adalimumab in patients with active luminal Crohn's disease.

Methods

25-Hydroxyvitamin D concentrations were measured in stored baseline samples from 659 infliximab- and 448 adalimumab-treated patients in the Personalised Anti-TNF Therapy in Crohn's disease (PANTS) study. Cut-offs for vitamin D were deficiency <25 nmol/L, insufficiency 25-50 nmol/L, and adequacy/sufficiency >50 nmol/L.

Results

About 17.1% (189/1107; 95% CI, 15.0-19.4) and 47.7% (528/1107; 95% CI, 44.8-50.6) of patients had vitamin D deficiency and insufficiency, respectively. 22.2% (246/1107) of patients were receiving vitamin D supplementation. Multivariable analysis confirmed that sampling during non-summer months, South Asian ethnicity, lower serum albumin concentrations, and non-treatment with vitamin D supplementation were independently associated with lower vitamin D concentrations. Pretreatment vitamin D status did not predict response or remission to anti-TNF therapy at week 14 (infliximab P_pnr = .89, adalimumab P_pnr = .18) or non-remission at week 54 (infliximab P = .13, adalimumab P = .58). Vitamin D deficiency was, however, associated with a longer time to immunogenicity in patients treated with infliximab, but not adalimumab.

Conclusions

Vitamin D deficiency is common in patients with active Crohn's disease. Unlike previous studies, pretreatment vitamin D concentration did not predict PNR to anti-TNF treatment at week 14 or nonremission at week 54.

Advances in understanding of effects of dietary nutrients in inflammatory bowel disease patients

The occurrence of inflammatory bowel disease (IBD) is influenced by environmental factors. Diet, as an important environmental factor, is closely associated with intestinal ecology and plays a critical role in the pathological process of IBD. This review summarizes the role of major dietary nutrients in the pathogenesis of IBD, with an aim to provide clues for the prevention and treatment of IBD.

Diet as a treatment for inflammatory bowel disease: is it ready for prime time?

PURPOSE OF REVIEW

Diet remains an important topic for patients with inflammatory bowel disease (IBD), yet few guidelines for dietary recommendations exist. There is a growing interest in the use of diet as treatment or adjuvant therapy for both ulcerative colitis and Crohn's disease. Here, we highlight the latest evidence on the use of diet for treatment of symptoms, active disease and maintenance of remission in ulcerative colitis and Crohn's disease.

RECENT FINDINGS

The Crohn's Disease Exclusion Diet (CDED) and the Specific Carbohydrate Diet (SCD) are studied diets that have gained popularity, but there is growing interest in the use and efficacy of less restrictive diets such as the Mediterranean diet. Recent data suggest healthful dietary patterns alone, with an emphasis on whole foods that are high in vegetable fibre and that promote less consumption of ultra-processed foods may also help achieve remission in patients with ulcerative colitis and Crohn's disease.

SUMMARY

In this review, we summarize the literature on diet as treatment for IBD. We highlight the latest clinical dietary studies, randomized clinical trials, as well as new and emerging diets for the treatment of IBD.

Role of vitamin D in ulcerative colitis: an update on basic research and therapeutic applications

INTRODUCTION

Vitamin D deficiency is common in patients with ulcerative colitis (UC). Moreover, vitamin D supplementation seems to contribute to disease relief. Nevertheless, the exact etiological link between vitamin D deficiency and UC is far from clear, and an agreement has not been reached on the frequency and dosage of vitamin D supplementation required.

AREAS COVERED

This review will outline the possible role of vitamin D in the pathogenesis of UC and summarize the current state of clinical research on vitamin D. Literature was searched on PUBMED, with 'Vitamin D,' 'Ulcerative colitis,' 'Vitamin D receptor,' and 'disease activity' as MeSH Terms. Relevant information is presented in figures or tables.

EXPERT OPINION

The etiological relationship between vitamin D and the onset of UC is still being researched. More high-quality double-blind randomized clinical studies are needed to determine the efficacy of vitamin D supplementation in the treatment of UC, whether as the main treatment or as an adjuvant treatment. Importantly, determining the dosage and frequency of vitamin D supplementation should be the main research direction in the future, and regional factors should also be fully considered in this respect.

Comparative analysis of the efficacy and accuracy of magnetic resonance imaging (MRI) and contrast-enhanced CT for residual and new lesions after transcatheter arterial chemoembolization (TACE) in patients with primary liver cancer

Background

The purpose of this study was to investigate the efficacy and accuracy of magnetic resonance imaging (MRI) and contrast-enhanced computed tomography (CECT) for residual and new lesions after transcatheter arterial chemoembolization (TACE) in patients with primary liver cancer (PHC).

Methods

Seventy-two PHC patients admitted to Linyi Central Hospital from May 2018 to May 2020 were selected as the study subjects, with a total of 92 lesions. All patients were treated with TACE, and were followed up at 6 months postoperatively. In addition, all patients underwent digital subtraction angiography (DSA), and with DSA results serving as the gold standard for diagnosis, the efficacy and accuracy of MRI and CECT for residual and new lesions after TACE in PHC patients were evaluated.

Results

There were no significant differences in the specificity between the two diagnostic methods (P>0.05), and the diagnostic accuracy and sensitivity of MRI were markedly higher than those of CECT (P<0.05). The number of residual and new lesions diagnosed by MRI was notably higher than that by multislice spiral computed tomography (MSCT) (P<0.05), and the detection rate of residual and new lesions after TACE in PHC patients with different types of iodized oil deposition by MRI was significantly higher than that by CECT (P<0.05). Also, the number of postoperative tumor capsules diagnosed by MRI was considerably higher than that by CECT (P<0.05). There were no significant differences between the two diagnostic methods in the score of residual enhancement appearances in the arterial phase after surgery (P>0.05). Furthermore, there were no notable differences between the two diagnostic methods in the diagnosis of portal vein tumorous emboli and the source of blood supply to lesions after surgery (P>0.05).

Conclusions

The diagnostic accuracy and sensitivity of MRI for residual and new lesions after TACE in PHC patients were higher than those of CECT. However, these two diagnostic methods were similar in diagnosing portal vein tumorous emboli, the source of blood supply to lesions, and the score of residual enhancement appearances in the arterial phase after surgery.

Probiotics and Vitamin D/Vitamin D Receptor Pathway Interaction: Potential Therapeutic Implications in Inflammatory Bowel Disease

Inflammatory bowel diseases (IBD) are chronic conditions of unknown etiology and immunomediated pathogenesis. In the last years, the comprehension of the complex mechanisms involved in the intestinal mucosal homeostasis, and the analysis of the alterations potentially leading to inflammatory pathologic states, has consistently increased. Specifically, the extraordinary impulse in the field of research of the intestinal microbiome has opened the door to the investigation of possible novel approaches to the diagnosis, management and therapeutic applications in IBD. In line with that, administration of probiotic bacteria has been intensely evaluated, leading to much more exciting results in experimental models than in clinical practice. Considering the consistent heterogeneity of the available studies on probiotics, the increased knowledge of the properties of the single bacterial species would ideally lead to unravel potential mechanisms of action that may bring therapeutic applications in specific pathologic condition. Among the relevant molecular pathways for mucosal homeostasis maintenance, the vitamin D/vitamin D receptor (VDR) pathway has been intensely studied in the very last years. In fact, besides osteometabolic functions, the vitamin D exerts important homeostatic effects in the organism at multiple levels, such as immunomodulation, inflammation control, and microbiota regulation, which are likely to play a relevant role in intestinal mucosa protection. In the present review, recent findings about probiotic applications in IBD and mechanisms of action linking vitamin D/VDR pathway to IBD are reported. Available evidence for probiotic effect on vitamin D/VDR are reviewed and potential future application in IBD patients are discussed. At present, many aspects of IBD pathogenesis are still obscure, and current therapeutic options for IBD treatment are at best suboptimal. The increasing comprehension of the different pathways involved in IBD pathogenesis will lead to novel findings ideally leading to potential clinical applications. Microbiota manipulation and vitamin/VDR pathway appear a promising field for future research and therapeutic developments.

Results of the Seventh Scientific Workshop of ECCO: Precision Medicine in IBD-Prediction and Prevention of Inflammatory Bowel Disease

Inflammatory bowel disease [IBD] is a complex chronic disorder with no clear aetiology and no known cure. Despite recent advances in overall disease management and improved therapeutics, patients with IBD still experience a substantial burden. Furthermore, as the incidence continues to increase in developing areas of the world, it is expected that the burden of IBD to society will increase and exert tremendous pressure on health care systems worldwide. Therefore, new strategies to prevent the global increase of IBD are urgently required. Data are being progressively acquired on the period preceding disease diagnosis, which support the concept that IBD has a preclinical period that may reveal the triggers of disease and may be amenable to early intervention. Having a better knowledge of this preclinical period will increase the potential not only for improved understanding of disease pathogenesis and improved therapeutics, but also for disease prediction and prevention.

Prenatal and Early Life Exposure to the Danish Mandatory Vitamin D Fortification Policy Might Prevent Inflammatory Bowel Disease Later in Life: A Societal Experiment

This register-based national cohort study of 206,900 individuals investigated whether prenatal exposure to small extra doses of vitamin D from fortified margarine prevented inflammatory bowel disease (IBD) later in life; whether the risk of IBD varied according to month or season of birth; and finally, whether there was an interaction between exposure to extra D vitamin and month or season of birth. Fortification of margarine with vitamin D was mandatory in Denmark from the mid-1930s until 1st June 1985, when it was abolished. Two entire birth cohorts, each including two years, were defined: one exposed and one unexposed to the fortification policy for the entire gestation. All individuals were followed for 30 years from the day of birth for an IBD diagnosis in Danish hospital registers. Logistic regression analyses were used to estimate odds ratios (OR) and 95% confidence intervals (CI). Odds for IBD was lower among those exposed to extra D vitamin compared to those unexposed, OR = 0.87 (95% CI: 0.79; 0.95). No association with month or season of birth was found. However, estimates suggested that particularly children born during autumn may have benefitted from the effect of small extra doses of vitamin D. This is, to our knowledge, the first study to explore if prenatal exposure to vitamin D from fortification influenced the risk of IBD. Our results suggest that prenatal exposure to small amounts of extra vitamin D from food fortification may protect against the development of IBD before 30 years of age.

The Role of Diet in the Pathogenesis and Management of Inflammatory Bowel Disease: A Review

Inflammatory bowel diseases, which include ulcerative colitis and Crohn’s disease, are chronic relapsing and remitting inflammatory diseases of the gastrointestinal tract that are increasing in prevalence and incidence globally. They are associated with significant morbidity, reduced quality of life to individual sufferers and are an increasing burden on society through direct and indirect costs. Current treatment strategies rely on immunosuppression, which, while effective, is associated with adverse events. Epidemiological evidence suggests that diet impacts the risk of developing IBD and modulates disease activity. Using diet as a therapeutic option is attractive to patients and clinicians alike due to its availability, low cost and few side effects. Diet may influence IBD risk and disease behaviour through several mechanisms. Firstly, some components of the diet influence microbiota structure and function with downstream effects on immune activity. Secondly, dietary components act to alter the structure and permeability of the mucosal barrier, and lastly dietary elements may have direct interactions with components of the immune response. This review will summarise the mechanisms of diet–microbial–immune system interaction, outline key studies examining associations between diet and IBD and evidence demonstrating the impact of diet on disease control. Finally, this review will outline current prescribed dietary therapies for active CD.

Mucosal vitamin D signaling in inflammatory bowel disease

Epidemiological studies have identified vitamin D (25(OH)D) deficiency to be highly prevalent among patients with inflammatory bowel disease (IBD), and low serum levels correlate with a higher disease activity and a more complicated disease course. The link to IBD pathogenesis has been subject of investigations, primarily due to the distinct immunological functions of vitamin D signaling, including anti-inflammatory and anti-fibrotic actions. Vitamin D is a pleiotropic hormone that executes its actions on cells through the vitamin D receptor (VDR). A leaky gut, i.e. an insufficient intestinal epithelial barrier, is thought to be central for the pathogenesis of IBD, and emerging data support the concept that vitamin D/VDR signaling in intestinal epithelial cells (IECs) has an important role in controlling barrier integrity. Here we review the latest evidence on how vitamin D promotes the interplay between IECs, the gut microbiome, and immune cells and thereby regulate the intestinal immune response. On the cellular level, vitamin D signaling regulates tight junctional complexes, apoptosis, and autophagy, leading to increased epithelial barrier integrity, and promotes expression of antimicrobial peptides as part of its immunomodulating functions. Further, intestinal VDR expression is inversely correlated with the severity of inflammation in patients with IBD, which might compromise the positive effects of vitamin D signaling in patients with flaring disease. Efforts to reveal the role of vitamin D in the pathophysiology of IBD will pave the road for the invention of more rational treatment strategies of this debilitating disease in the future.

Levels of Vitamin D Are Low After Crohn's Disease Is Established But Not Before

BACKGROUND & AIMS

Low serum levels of vitamin D have been associated with Crohn's disease (CD). However, it is unclear whether low vitamin D levels cause CD or CD reduces serum vitamin D.

METHODS

United States military personnel with CD (n = 240) and randomly selected individuals without CD (controls, n = 240) were matched by age, sex, race, military branch, and geography. We measured 25-hydroxyvitamin D in sera 8-3 years (pre-2) and 3 years to 3 months before diagnosis (pre-1) and 3 months before through 21 months after diagnosis (pre-0). We genotyped VDR and GC vitamin D related polymorphisms. We used conditional logistic regression, including adjustments for smoking, season, enlistment status, and deployment, to estimate relative odds of CD according to vitamin D levels and interactions between genetic factors and levels of vitamin D.

RESULTS

Levels of vitamin D before diagnosis were not associated with CD in pre-2 (P trend = .65) or pre-1 samples (P trend = .84). However, we found an inverse correlation between CD and highest tertile of vitamin D level in post-diagnosis samples (P trend = .01; odds ratio, 0.51; 95% CI, 0.30-0.86). Interactions were not detected between vitamin D levels and VDR or GC polymorphisms. We observed an association between VDR Taq1 polymorphism and CD (independent of vitamin D) (P = .02).

CONCLUSIONS

In serum samples from military personnel with CD and matched controls, we found no evidence for an association between CD and vitamin D levels up to 8 years before diagnosis. However, we observed an inverse-association between post-diagnosis vitamin D levels and CD. These findings suggest that low vitamin D does not contribute to development of CD-instead, CD leads to low vitamin D.

The role of vitamin D in inflammatory bowel disease: a guide for clinical practice

INTRODUCTION

Inflammatory bowel disease (IBD) is a chronic inflammatory condition of the gastrointestinal tract that carries significant morbidity and mortality. Given the need to identify modifiable risk factors to prevent IBD development and to mitigate disease severity, vitamin D has become a major candidate of interest.

AREAS COVERED

In this review, we discuss the regulatory role played by vitamin D in intestinal immune homeostasis, updates in the recent literature exploring its role in de novo IBD pathogenesis and established IBD activity. We also discuss societal recommendations on its therapeutic role in maintaining bone health and future directions for studying its role in regulating disease activity.

EXPERT OPINION

In contrast to findings from earlier studies suggesting a causal role in IBD, recent findings indicate that vitamin D deficiency may be a sequela rather than a cause of IBD. Additionally, clinical trials exploring vitamin D therapy in reducing disease activity remain inconclusive thus far, with the current evidence best supporting a therapeutic role of vitamin D in bone health. Future studies are needed to clarify the role of vitamin D in IBD development and disease activity and to determine its therapeutic potential for IBD disease activity.

Intestinal vitamin D receptor knockout protects from oxazolone-induced colitis

Crohn’s disease (CD) and ulcerative colitis (UC) actually had different pathological mechanisms, as the former was mainly induced by Th1 and Th17 response and the latter by Th2 response. Our previous study found that oxazolone-induced Th2-mediated colitis could not be attenuated by vitamin D supplementation. This study investigated the influence of intestinal vitamin D receptor (VDR) knockout on oxazolone-induced colitis and explored the possible immunological mechanism. Intestinal VDR knockout mice had milder oxazolone-induced colitis than wildtype controls, as demonstrated by less body weight decrease and faster recovery, more intact local structure, reduced cell apoptosis, and better preserved barrier function. Th2-mediated inflammation was significantly inhibited by VDR deficiency. Meanwhile, the percentage of invariant natural killer T (iNKT) cells did not increase as much in intestinal VDR knockout mice as in wild-type controls, nor did the iNKT cells develop normally as in the controls. Intestinal VDR knockout protected against oxazolone-induced colitis in mice by blocking Th2 cell response and reducing the function of intestinal iNKT cells. Vitamin D status had no influence on the severity of colitis. This study may explain the diverse outcomes after vitamin D supplementation in literature and add some clue to the targeted therapy of IBD.

Personalized Nutrition for Inflammatory Bowel Disease

A person’s diet may impact inflammatory bowel disease (IBD) risk. IBD is an inflammatory condition. We explore how certain foods may trigger, or indeed attenuate, inflammation in some IBD patients, but not others. Greater knowledge is needed underpinning personalized nutrition within effective medical management.

New therapeutic strategies for combatting gastrointestinal toxicity

PURPOSE OF REVIEW

An overwhelming majority of chemotherapy agents are known to cause gastrointestinal mucositis, an unwanted side effect of cancer treatment, for which no effective treatment currently exists. The pathological processes underlying the development of gastrointestinal mucositis are many and varied, with multiple pathways thought to be involved in initiation of inflammation and apoptosis. Physiological and or biochemical-based deficiencies, such as vitamin D deficiency and gut microbiome density and population, are also thought to have an impact on mucositis severity.

RECENT FINDINGS

Recent studies investigating inflammatory pathways, such as cytokines and apoptotic markers, do show that interleukin-blocking proteins alleviate symptoms of gastrointestinal mucositis. However, the effectiveness of these treatments varies depending on the type of anticancer agent administered, meaning blocking compounds may be limited in their application. Targeting the host's gut microbiome in preventing dysbiosis is also thought to be a potential avenue for exploration. The use of probiotic gut bacteria (i.e. Lactobacillus spp.), while beneficial in preventing chemotherapy radiotherapy-induced diarrhoea, does not seem to alleviate the physiological damage caused by gastrointestinal mucositis. Vitamin D has been widely shown to have a host of anti-inflammatory and immunomodulatory effects in the intestine, as well as anticancer properties and therefore, may reduce severity of gastrointestinal mucositis.

SUMMARY

While anti-inflammatory and antiapoptotic agents have shown promise in animal models of gastrointestinal mucositis, there is still no singular mechanism allowing for the development of a therapeutic drug to prevent or cure gastrointestinal injury. A greater insight into the exact mechanistic actions of both probiotics and vitamin D might reveal how to improve their use as therapeutic treatments for gastrointestinal mucositis.

Inflammatory bowel diseases: interrelationships between dietary vitamin D, exposure to UV radiation and the fecal microbiome

Introduction: Environmental factors and an altered fecal microbiome are believed to be central to the pathogenesis of inflammatory bowel diseases (IBD). Vitamin D and ultraviolet radiation (UVR) are environmental factors that are associated by several pathways, including changes to the gastrointestinal microbiome, with the development and course of IBD.Area covered: This review explores the interaction of vitamin D, and UVR, with the intestinal innate and adaptive immune systems, and how they may influence the gut microbiome and the subsequent development, and progression, of IBD.Expert opinion: Vitamin D and UVR both regulate innate and adaptive immunity through a combination of common and independent mechanisms, with the overall effect being the promotion of immune tolerance. Vitamin D, and to a lesser extent UVR, can modify the gastrointestinal microbiome either directly, or through immune-mediated mechanisms and this may explain the effect on intestinal inflammation in animal models of IBD and some clinical studies. Thus, both vitamin D and UVR exposure can be considered potential 'master regulators' of gastrointestinal immunity, fine-tuning the complex interaction between genetics, host immunity and the gut microbiome. Further research and increased understanding of environment-host interactions is essential to achieving the ultimate goal of preventing and curing IBD.

Vitamin D deficiency associated with Crohn's disease and ulcerative colitis: a meta-analysis of 55 observational studies

PURPOSE

To investigate the association of serum levels of 25(OH)D and 1,25(OH)₂D₃ in healthy and non-healthy controls with Crohn's disease (CD) and ulcerative colitis (UC).

METHODS

Three electronic databases: PubMed, EMbase and EBSCOhost CINAHL, were searched for observational studies to measure the relationship between serum levels of vitamin D (VitD) and CD (or UC).

RESULTS

Fifty-five studies were included in the meta-analysis. We found that mean serum 25(OH)D levels in patients with CD were significantly lower than those in healthy controls (MD: - 3.17 ng/mL; 95% CI - 4.42 to - 1.93). Results from the meta-analysis examining 1,25(OH)₂D₃ levels in Crohn's patients revealed higher levels in the CD group than in healthy (MD: 3.47 pg/mL; 95% CI - 7.72 to 14.66) and UC group (MD: 5.05 pg/mL; 95% CI - 2.42 to 12.52). Serum 25(OH)D levels were lower in the UC group than in the healthy control group (MD: - 2.52 ng/mL; 95% CI - 4.02 to - 1.02). In studies investigating the level of 1,25(OH)₂D₃ in UC and healthy control groups, the level of 1,25(OH)₂D₃ in the UC groups were found to be higher than that in the control groups (MD: 3.76 pg/mL; 95% CI - 8.36 to 15.57). However, the 1,25(OH)₂D₃ level in patients with UC was lower than that in CD groups (MD: - 6.71 pg/mL; 95% CI - 15.30 to 1.88). No significant difference was noted between CD patients and UC patients in terms of average serum 25(OH)D levels.

CONCLUSIONS

This study found that VitD levels were inversely related to CD and UC. Serum levels of 25(OH)D were lower in patients with CD and UC than in healthy people, and more than half of the patients had insufficient vitamin D levels. The serum level of 1,25(OH)₂D₃ in both the CD and UC groups was higher than that in healthy people.

Vitamin D in inflammatory bowel disease: From biology to clinical implications

Inflammatory bowel disease (IBD) is a chronic immune-mediated inflammatory disorder of the gastrointestinal tract consisting two principal categories, ulcerative colitis (UC) and Crohn's disease (CD). The precise etiology of IBD remains unknown. Vitamin D is an important micronutrient that plays a critical biological role in various processes in human tissues. However, the relationship between disruption of the gut microbiota and the development of IBD is unclear. Some studies suggest that IBD is the cause of disrupted gut microbiota while others propose that gut microbiota itself can lead to development of IBD. Regardless of this complexity, it has emerged that vitamin D is an immunoregulatory factor that plays a significant role in the pathogenesis of IBD by affecting the gut microbiome and the inflammatory response. It has been reported that 38.1% of CD patients and 31.6% of UC patients suffer from vitamin D deficiency (VDD). In this review, we aimed to evaluate the association between VDD and IBD, summarizing recent clinical studies examining the effect of low vitamin D and the role of vitamin D supplementation on IBD clinical outcomes.

Current evidence for vitamin D in intestinal function and disease

Vitamin D activity is associated with the modulation of a wide variety of biological systems, in addition to its roles in calcium homeostatic mechanisms. While vitamin D is well known to promote gastrointestinal calcium absorption, vitamin D also plays a role in attenuating and/or preventing the progression of several gastrointestinal diseases including Crohn’s disease, ulcerative colitis, and colorectal cancer, and may also play a role in chemotherapy-induced intestinal mucositis. The pro-differentiation, immunomodulatory, and anti-inflammatory effects of vitamin D, which has been reported in numerous circumstances, are key potential mechanisms of action in the prevention of gastrointestinal disorders. While the debate of the effectiveness of vitamin D to treat bone pathologies continues, the clinical importance of vitamin D therapy to prevent gastrointestinal disorders should be investigated given current evidence, using both nutritional and pharmaceutical intervention approaches.

Impact statement

The non-skeletal functions of vitamin D play an important role in health and disease. The anti-inflammatory properties and maintenance of intestinal function fulfilled by vitamin D impact other systems in the body though downstream processing. This review provides insight into the mechanisms underpinning the potential benefits of vitamin D in both maintaining intestinal homeostasis and associated diseased states.

Vitamin D metabolites are lower with active Crohn's disease and spontaneously recover with development of remission

BACKGROUND

Vitamin D deficiency is associated with active Crohn's disease (CD). However, it remains unclear if lower 25-hydroxyvitamin D [25(OH)D] concentration is the cause, or consequence, of intestinal inflammation. Existing literature has focused on circulating 25(OH)D rather than the active metabolite 1,25(OH)₂D, or its breakdown product, 24,25(OH)₂D. We aimed to characterise vitamin D metabolism in a cohort of patients with active and inactive CD.

METHODS

Fifty-four patients with CD and not on corticosteroids or vitamin D supplements, were enrolled in a 6-month prospective cohort study. Sera were collected on enrolment and at 6 months and tested for 25(OH)D, 1,25(OH)₂D, 24,25(OH)₂D using liquid chromatography tandem mass spectroscopy as well as vitamin-D-binding protein.

RESULTS

There were no differences in 25(OH)D or 1,25(OH)₂D levels between participants with active versus inactive disease. Levels of 24,25(OH)₂D were significantly lower in those with active compared with inactive disease (mean 3.9 versus 6.0 µmol/l; p = 0.007) and therefore the ratio of 25(OH)D:24,25(OH)₂D was higher (mean 17.3 versus 11.1; p = 0.001). In those patients with active disease who achieved remission, there was a mean increase in 25(OH)D of 32.3 nmol/l (i.e. to a level in the sufficient range) and 24,25(OH)₂D of 2.1 µmol/l. These increases were not seen in patients with persistently active or inactive disease.

CONCLUSION

Levels of 24,25(OH)₂D, but not 25(OH)D, were lower in patients with active CD, and spontaneously increased with resolution of underlying inflammation. The utility of 24,25(OH)₂D as a biomarker of disease activity and vitamin D status in CD warrants further exploration.

Seasonal variability of vitamin D status in patients with inflammatory bowel disease - A retrospective cohort study

Objectives

Vitamin D deficiency predicts unfavorable disease outcomes in inflammatory bowel disease. Endogenous vitamin D synthesis is affected by seasonal factors including sunlight exposure, raising the question whether seasonality determines the risk of vitamin D deficiency and may mask other clinical risk factors.

Methods

Univariable and multiple regression analyses were performed in a retrospective cohort of 384 patients to determine risk factors for vitamin D deficiency. Since the observed 25-hydroxyvitamin D [25(OH)D] concentrations followed a sinusoidal pattern over the year, all 25(OH)D concentrations were normalized for the predicted variability of the respective day of analysis based on a sinusoidal regression analysis of 25(OH)D test results obtained in more than 86,000 control serum samples.

Results

Vitamin D deficiency was highly prevalent in patients with Crohn’s disease or ulcerative colitis (63% and 55%, respectively) and associated with winter/spring seasons. After normalization of 25(OH)D concentrations for the day of analysis, vitamin D deficiency was associated with histories of complications related to inflammatory bowel disease, surgery, smoking and ongoing diarrhea while initial disease manifestation during adulthood, ongoing vitamin D supplementation and diagnosis of ulcerative colitis vs. Crohn’s disease appeared to be protective. Multiple regression analyses revealed that vitamin D deficiency was associated with disease activity in Crohn’s disease and anemia in ulcerative colitis patients. Only few deficient patients achieved sufficient 25(OH)D concentrations over time. However, increasing 25(OH)D concentrations correlated with improved Crohn’s disease activity.

Conclusions

Vitamin D deficiency was highly prevalent in patients with Crohn’s disease and ulcerative colitis and dependent on the season of the year. Following normalization for seasonality by sinusoidal regression analysis, vitamin D deficiency was found to be associated with parameters of complicated disease course while increasing 25(OH)D concentrations over time correlated with reduced activity of Crohn’s disease.

Vitamin D deficiency in adult patients with ulcerative colitis: Prevalence and relationship with disease severity, extent, and duration

BACKGROUND

Vitamin D plays a key role in gut immunity and maintenance of the mucosal barrier. Vitamin D deficiency (VDD) worsens ulcerative colitis (UC) and its supplementation ameliorates the disease in mouse models. The prevalence and predictors of VDD in UC are not known.

METHODS

Consecutive patients with UC (n = 80) underwent clinical, endoscopic, and histological evaluation to assess the extent, severity using UC disease activity index (UCDAI) score, and duration of illness. An equal number of age and gender-matched healthy adults without any features of inflammatory bowel disease (IBD) living in the same latitude were identified as controls. The serum 25-hydroxy vitamin D₃ level was estimated. The subjects were classified as deficient (< 20 ng/mL), insufficient (20-32 ng/mL), sufficient (32-80 ng/mL), and optimal (> 80 ng/mL) based on vitamin D levels. Chi-square test and Mann-Whitney U test were done to identify factors associated with vitamin D deficiency.

RESULTS

The patients and controls were similar in age and gender (40 ± 11.4 years, 51% male vs. 40 ± 12 years, 51% male; p = 1.000). Median vitamin D levels among patients were lower than the controls (18.1 ng/mL [IQR 14] vs. 32.5 ng/mL [IQR 36]; p < 0.001). Patients were more often VDD (56% vs. 40%) or insufficient (34% vs. 9%) and less often sufficient (9% vs. 40%) or optimal (1% vs. 11%), in contrast to controls (p < 0.001). Median vitamin D levels were lower in those with UCDAI > 6 (15 vs. 21 ng/mL; p = 0.01), having pancolitis (13 vs. 21 ng/mL, p = 0.01), and longer duration of illness > 2 years (13.8 vs. 20.8; p = 0.025). Vitamin D levels showed a negative correlation with frequency of stools (rho = - 0.244, p = 0.05), disease duration (rho = - 0.244, p = 0.007) and UCDAI score (r = - 0.348, p = 0.002).

CONCLUSION

VDD is highly prevalent among patients with UC. Patients with longer disease duration, more severe symptoms, and pancolitis are likely to have lower vitamin D levels.

A New Model Based on 25-Hydroxyvitamin D3 for Predicting Active Crohn's Disease in Chinese Patients

Background

The association between vitamin D3 and activity of Crohn's disease (CD) is unclear in Chinese patients. In this study, we aimed to evaluate the correlations between serum levels of 25-hydroxyvitamin D3 (25(OH)D3) and disease activity and predict active disease based on vitamin D status.

Methods

Between January 2014 and December 2017, 346 CD patients from the First Affiliated Hospital of Sun Yat-sen University were recruited and categorized into a group with 25(OH)D3 ≤ 20 ng/ml and a group with 25(OH)D3 > 20 ng/ml. The clinical characteristics, medication, and health-care needs were compared between the groups. The correlations among 25(OH)D3 and routine serum biomarkers and disease activity were examined. The predictive efficiency of 25(OH)D3 and other biomarkers for active diseases was also explored using receiver-operating characteristic (ROC) curve analysis. A new predictive model, −(5^∗25(OH)D3 + 2^∗Hb) + ESR, and a nomogram were established using Logistic Regression.

Results

Patients with 25(OH)D3 ≤ 20 ng/ml had higher serum levels of C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), and platelets (PLT) and lower levels of hemoglobin (Hb) and albumin (ALB). Serum levels of 25(OH)D3 were inversely correlated with the score of Crohn's Disease Activity Index (CDAI) (r_s = −0.608). ROC analysis showed a better predictive value of −25(OH)D3 and the new model with areas under curve (AUC) of 0.804 and 0.879, respectively, than those of CRP (0.693) and ESR (0.713) in disease activity. A nomogram for prediction was established with a c-index of 0.882.

Conclusions

Serum levels of 25(OH)D3 negatively correlated with CD activity in Chinese patients. The new model and a nomogram based on 25(OH)D3 showed a better efficiency in predicting disease activity in CD patients but warrants further study.

High-dose vitamin D3 supplementation decreases the number of colonic CD103+ dendritic cells in healthy subjects

PURPOSE

Vitamin D may induce tolerance in the intestinal immune system and has been shown to regulate the phenotype of tolerogenic intestinal dendritic cells (DCs) in vitro. It is unknown whether vitamin D supplementation affects human intestinal DCs in vivo, and we aimed to investigate the tolerability and effect on intestinal CD103⁺DCs of high-dose vitamin D₃ treatment in healthy subjects.

METHODS

Ten healthy subjects received a total of 480,000 IU oral vitamin D₃ over 15 days and colonic biopsies were obtained before and after intervention by endoscopy. Lamina propria mononuclear cells (LPMCs) were isolated from the biopsies, stained with DC surface markers and analysed with flow cytometry. Snap-frozen biopsies were analysed with qPCR for DC and regulatory T cell-related genes.

RESULTS

No hypercalcemia or other adverse events occurred in the test subjects. Vitamin D decreased the number of CD103⁺ DCs among LPMCs (p = 0.006). Furthermore, vitamin D induced mRNA expression of TGF-β (p = 0.048), TNF-α (p = 0.006) and PD-L1 (p = 0.02) and tended to induce IL-10 expression (p = 0.06). Multivariate factor analysis discriminated between pre- and post-vitamin D supplementation with a combined increased qPCR expression of PD1, PD-L1, TGF-β, IL-10, CD80, CD86, FOXP3, NFATc2 and cathelicidin.

CONCLUSION

High-dose vitamin D supplementation is well tolerated by healthy subjects and has a direct effect on the CD103⁺ DCs, local cytokine and surface marker mRNA expression in the colonic mucosa, suggestive of a shift towards a more tolerogenic milieu.