Variation in incidence of pediatric Crohn's disease in relation to latitude and ambient ultraviolet radiation: a systematic review and analysis

Environmental risk factors of inflammatory bowel disease: toward a strategy of preventative health

The pathogenesis of inflammatory bowel disease (IBD) involves a complex interplay between genetic, environmental, and microbial factors. Many of these environmental determinants are modifiable, offering opportunities to prevent disease or delay its onset. Advances in the study of preclinical IBD cohorts offer the potential to identify biomarkers that predict individuals at high risk of developing IBD, enabling targeted environmental interventions aimed at reducing IBD incidence. This review summarizes findings from 79 meta-analyses on modifiable environmental factors associated with the development of IBD. Identified risk factors include smoking, Western diets, ultra-processed foods, and early life antibiotic use, while protective factors include breastfeeding, Mediterranean diets rich in fiber, plant-based foods, and fish, along with an active physical lifestyle. Despite the promise shown by observational data, interventional or randomized controlled studies evaluating the efficacy of modifying environmental risk factors remain limited and mostly focus on dietary intervention. This review aims to inform the design of higher quality interventional and randomized controlled studies for disease prevention while providing actionable guidance to healthcare providers on reducing the risk of developing IBD through environmental modifications.

A systematic review and meta-regression on international trends in the incidence of ulcerative colitis in children and adolescents associated with socioeconomic and geographic factors

The incidence of ulcerative colitis (UC) among children and adolescents is rising globally, albeit with notable discrepancies across countries. This systematic review and meta-analysis aims to provide a comprehensive overview of the incidence rates of pediatric UC in various countries and explore potential influencing factors. A systematic literature search was conducted in PubMed and EMBASE (via OVID) for studies published between January 1, 1970, and December 31, 2019. Additionally, a manual search was performed to identify relevant systematic reviews. Meta-analyses and meta-regressions were employed to determine the overall incidence rate and examine potential factors that may influence it. A total of 66 studies were included in the qualitative analysis, while 65 studies were included in the meta-analysis and 50 studies were meta-regression. The study reports a rising incidence of pediatric UC in several countries but significant differences across geographic regions, with no discernible global temporal trend. In addition, our meta-regression analysis showed that geographic location and socioeconomic factors significantly influenced the incidence of UC.

CONCLUSION

Our findings indicate a rising incidence of pediatric UC in numerous countries since 1970, but with significant geographical variation, potentially presenting challenges for respective healthcare systems. We have identified geographic and socioeconomic factors that contribute to the observed heterogeneity in incidence rates. These findings provide a foundation for future research and health policies, aiming to tackle the growing burden of UC among children and adolescents.

WHAT IS KNOWN

• The incidence of ulcerative colitis in childhood and adolescence appears to be increasing worldwide and varies internationally. • Environmental and lifestyle factors are suspected as potential causes.

WHAT IS NEW

• Our results highlight that the heterogeneity in incidence rates can be attributed to geographic and socio-economic factors.

Correlation of Socioeconomic and Environmental Factors With Incidence of Crohn Disease in Children and Adolescents: Systematic Review and Meta-Regression

BACKGROUND

The worldwide incidence of Crohn disease (CD) in childhood and adolescence has an increasing trend, with significant differences between different geographic regions and individual countries. This includes an increase in the incidence of CD in countries and geographic regions where CD was not previously prevalent. In response to the increasing incidence, the pediatric care landscape is facing growing challenges.

OBJECTIVE

This systematic review and meta-analysis were undertaken to comprehensively delineate the incidence rates of CD in pediatric populations across different countries and to explore potential influencing factors.

METHODS

We performed a systematic review of PubMed and Embase (via Ovid) for studies from January 1, 1970, to December 31, 2019. In addition, a manual search was performed in relevant and previously published reviews. The results were evaluated quantitatively. For this purpose, random effects meta-analyses and meta-regressions were performed to investigate the overall incidence rate and possible factors influencing the incidence.

RESULTS

A qualitative synthesis of 74 studies was performed, with 72 studies included in the meta-analyses and 52 in the meta-regressions. The results of our meta-analysis showed significant heterogeneity between the individual studies, which cannot be explained by a sample effect alone. Our findings showed geographical differences in incidence rates, which increased with increasing distance from the equator, although no global temporal trend was apparent. The meta-regression analysis also identified geographic location, UV index, and Human Development Index as significant moderators associated with CD incidence.

CONCLUSIONS

Our results suggest that pediatric CD incidence has increased in many countries since 1970 but varies widely with geographic location, which may pose challenges to the respective health care systems. We identified geographic, environmental, and socioeconomic factors that contribute to the observed heterogeneity in incidence rates. These results can serve as a basis for future research. To this end, implementations of internationally standardized and interoperable registries combined with the dissemination of health data through federated networks based on a common data model, such as the Observational Medical Outcomes Partnership, would be beneficial. This would deepen the understanding of CD and promote evidence-based approaches to preventive and interventional strategies as well as inform public health policies aimed at addressing the increasing burden of CD in children and adolescents.

TRIAL REGISTRATION

PROSPERO International prospective register of systematic reviews CRD42020168644; https://www.crd.york.ac.uk/PROSPERO/display_record.php?RecordID=168644.

INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID)

RR2-10.1136/bmjopen-2020-037669.

Descriptive Epidemiology of Pediatric Inflammatory Bowel Disease in Oceania: A Systematic Review and Meta-Analysis

OBJECTIVES

Pediatric inflammatory bowel diseases (IBDs) are chronic, idiopathic illnesses of the digestive tract, which can impact adversely on children's quality of life and burden health systems. International studies have shown these diseases are increasing. The aim was to describe pediatric IBD epidemiology across Oceania by conducting a systematic review and meta-analysis of incidence and prevalence.

METHODS

Medline, EMBASE and Web of Science databases were searched in October 2022 for studies reporting rates of IBD, Crohn disease (CD), or ulcerative colitis (UC) in children (≤19 years). Several data collection methodologies were included and pooled estimates of incidence and prevalence were calculated using a random effects model with I2 measures of heterogeneity.

RESULTS

Nineteen articles provided 15 incidence and 7 prevalence studies. Fourteen studies were from Australia, 8 studies from New Zealand, and no studies were found from the Pacific Islands. Study dates ranged from 1950 to 2020 with 11 studies using population-based designs. Pooled estimates for annual incidence were IBD 4.1 (3.4-4.8, I2 = 98.7), CD 2.3 (1.9-2.7, I2 = 98.6), and UC 0.9 (0.6-1.1, I2 = 96.8) per 100,000 person-years. Prevalence rates were IBD 36.0 (23.5-48.5, I2 = 98.4), CD 23.2 (6.6-39.8, I2 = 97.8), and UC 7.6 (2.7-12.5, I2 = 99.6) per 100,000 persons.

CONCLUSIONS

Pediatric IBD is prevalent in Oceania with high incidence rates, particularly for CD. Low rates of IBD were observed in indigenous Australian, Māori, and New Zealand Pacific children and there were no studies from the Pacific Islands highlighting this as an area in need of further research.

Geosocial Features and Loss of Biodiversity Underlie Variable Rates of Inflammatory Bowel Disease in a Large Developing Country: A Population-Based Study

BACKGROUND

The epidemiology of inflammatory bowel disease (IBD) in developing countries may uncover etiopathogenic factors. We investigated IBD prevalence in Brazil by investigating its geographic, spatial, and temporal distribution, and attempted to identify factors associated with its recent increase.

METHODS

A drug prescription database was queried longitudinally to identify patients and verify population distribution and density, race, urbanicity, sanitation, and Human Development Index. Prevalence was calculated using the number of IBD patients and the population estimated during the same decade. Data were matched to indices using linear regression analyses.

RESULTS

We identified 162 894 IBD patients, 59% with ulcerative colitis (UC) and 41% with Crohn's disease (CD). The overall prevalence of IBD was 80 per 100 000, with 46 per 100 000 for UC and 36 per 100 000 for CD. Estimated rates adjusted to total population showed that IBD more than triplicated from 2008 to 2017. The distribution of IBD demonstrated a South-to-North gradient that generally followed population apportionment. However, marked regional differences and disease clusters were identified that did not fit with conventionally accepted IBD epidemiological associations, revealing that the rise of IBD was variable. In some areas, loss of biodiversity was associated with high IBD prevalence.

CONCLUSIONS

When distribution is considered in the context of IBD prevalence, marked regional differences become evident. Despite a background of Westernization, hotspots of IBD are recognized that are not explained by population density, urbanicity, sanitation, or other indices but apparently are explained by biodiversity loss. Thus, the rise of IBD in developing countries is not uniform, but rather is one that varies depending on yet unexplored factors like geoecological conditions.

EPIDEMIOLOGIC ASPECTS OF INFLAMMATORY BOWEL DISEASE IN THE WESTERN REGION OF MINAS GERAIS STATE

BACKGROUND

Crohn's disease (CD) and ulcerative colitis (UC), two of the main inflammatory bowel diseases (IBD), have been increasingly diagnosed in South America. Although IBD have been intensively studied in the last years, epidemiologic data in Brazil are scarce.

OBJECTIVE

To study the clinical and epidemiologic profile of IBD patients treated in the Clinical Hospital of the Federal University of Uberlândia from 1999 to 2014.

METHODS

We performed a retrospective study of the medical records of patients diagnosed with IBD, according to the international classification of diseases (ICD) - ICD K50 for CD and ICD K51 for UC - confirmed by endoscopic examination in the case of both diseases. We analyzed the following variables: age; sex; ethnicity; smoking habit; primary diagnosis; site of disease manifestation; main clinical manifestations; IBD-related complications; extraintestinal manifestations; and established drug and/or surgical treatment.

RESULTS

We evaluated 183 IBD cases (91 UC and 92 CD cases). The estimated prevalence rate of UC was 15.06/100.000 inhabitants and of CD was 15.23/100.000. The CU and CD female to male incidence ratios were 1.7 and 1.8, respectively. The average age of patients diagnosed with UC was 39.4 years and of those diagnosed with CD was 31.1 years. White-skinned people were the most affected by UC (66.0%) and CD (69.0%). Few patients were submitted to surgical procedures as treatment alternative.

CONCLUSION

The estimated prevalence of IBD in this population was low compared to that of populations of North America, but high compared to that of other regions considered to present low incidence, such as some Asian and Latin American countries.

Insolation and Disease Severity in Paediatric Inflammatory Bowel Disease-A Multi-Centre Cross-Sectional Study

This study was to investigate whether the clinical course of inflammatory bowel disease (IBD) in a Polish paediatric cohort fits a seasonal pattern and depends on insolation. Two hundred and fourteen patients diagnosed with Crohn's disease (CD) and 192 with ulcerative colitis (UC) aged from 3 to 18 years, were recruited in seven centres of similar latitude. The seasons were defined as winter (December-February), spring (March-May), summer (June-August), autumn (September-November). The year was also divided depending on insolation threshold (3.0 kWh/m²/day). Patients diagnosed with IBD when the isolation was >3 kWh/m²/day had poorer nutritional status than those diagnosed while insolation was below threshold (lower standardised BMI at diagnosis (-0.81 ([-1.34]-[-0.03]) vs. -0.52 ([-1.15]-0.15); p = 0.0320) and worst flare (-0.93 ([-1.37]-[-0.05]) vs. -0.66 ([-1.23]-0.17); p = 0.0344), with the need for more frequent biological treatment (45.5% vs. 32.7%, p = 0.0100). Patients diagnosed in winter were significantly younger at diagnosis (11.4 vs. 13.0; p_adj = 0.0180) and first immunosuppressive treatment (11.3 vs. 13.3; p_adj = 0.0109) than those diagnosed in other seasons. CD patients diagnosed in months with higher insolation spent more days in hospital than those diagnosed in months with lower insolation [4.6 (1.8-11.8) vs. 2.9 (1.3-6.2); p = 0.0482]. CD patients diagnosed in summer had significantly more concomitant diseases. In patients with CD, the occurrence of the worst flare was more frequent in autumn. Furthermore, the season of birth was associated with Pediatric Crohn's Disease Activity Index at worst flare and earlier surgery. In conclusion, several clinical parameters are associated with insolation, the season of diagnosis and season of birth in the clinical course of Crohn's disease.

Sunlight exposure in inflammatory bowel disease outpatients: Predictive factors and correlation with serum vitaminD

INTRODUCTION

Sunlight exposure is the main source of vitaminD. Our aim was to describe both sun exposure and sun protection behaviour in a series of patients with inflammatory bowel disease (IBD), and to study their potential association with vitaminD concentration.

PATIENTS AND METHODS

A cross sectional, observational study. The clinical-demographic variables were obtained via clinical interviews and medical history review. The sunlight exposure assessment was carried out using the Sun Exposure Questionnaire and the concentration of 25-hydroxy vitaminD (25OHD) was measured by an electro-chemiluminescence immunoassay. Questionnaires were conducted on quality of life, physical activity, weekly vitaminD intake and sun protection behaviour.

RESULTS

149 patients were included. In 69% of patients, deficient or insufficient 25OHD values were recorded. 67% showed low sun exposure. A modest significant correlation was observed between the total score of the solar exposure questionnaire and the 25OHD concentration in the complete series (r=0.226, P=.006) and in the summer (r=0.274, P=.01). The sun protection behaviour questionnaire score did not influence the 25OHD concentration. In the multivariate analysis, only the presence of clinical activity was associated with low sun exposure (OR=3.23).

DISCUSSION

Sun exposure according to the questionnaire used was low, was associated with the presence of clinical activity and was weakly correlated with serum 25OHD concentration. More studies are needed to explore the use of individual questionnaires for sun exposure and its relationship with vitaminD in patients with IBD.

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.

Higher Sun Exposure is Associated With Lower Risk of Pediatric Inflammatory Bowel Disease: A Matched Case-control Study

OBJECTIVES

The incidence of pediatric inflammatory bowel disease (IBD) is increasing worldwide. Ecological studies show higher incidence in regions at higher latitude or lower ambient ultraviolet radiation; individual-level associations with sun exposure have not been assessed.

METHODS

We recruited children (0-17 years) with IBD from 2 large hospitals in Melbourne, Australia. Control participants were recruited from the day surgery unit of one of the same hospitals. Questionnaires provided data on demographics, past sun exposure, the likelihood of sunburn (skin sensitivity) or tanning following sun exposure, use of sun protection, physical activity, and parental smoking and education. Grandparent ancestry was used to determine participant ethnicity. Cases and controls were matched on age and sex. We used conditional logistic regression to test the association between being an IBD case and past sun exposure at different ages, adjusted for a range of other factors.

RESULTS

After matching, n = 99 cases and n = 396 controls were included in the analysis. In multivariable analysis, for each 10 min increment in leisure-time sun exposure in summer or winter there was a linear 6% reduction in the odds of having IBD (P = 0.002). Results were similar in sensitivity analyses including only the most recently diagnosed cases, only Caucasian cases and controls, only those with symptom onset within the year before study entry, or additionally adjusted for age or physical activity.

CONCLUSIONS

Higher sun exposure in the previous summer or winter was associated with a reduced risk of having IBD. There are plausible pathways that could mediate this effect.

Dietary Composition and Effects in Inflammatory Bowel Disease

Dramatic changes in the environment and human lifestyle have been associated with the rise of various chronic complex diseases, such as inflammatory bowel disease (IBD). A dysbiotic gut microbiota has been proposed as a crucial pathogenic element, contributing to immune imbalances and fostering a proinflammatory milieu, which may be associated with disease relapses or even the initiation of IBD. In addition to representing important regulators of the mucosal immunity and the composition of the gut microbiota, food components have been shown to be potential environmental triggers of epigenetic modifications. In the context of chronic intestinal inflammation, dietary habits and specific food components have been implicated as important modulators of epigenetic mechanisms, including DNA methylation, which may predispose a person to the increased risk of the initiation and evolution of IBD. This review provides novel insights about how dietary factors may interact with the intestinal mucosa and modulate immune homeostasis by shaping the intestinal ecosystem, as well as the potential influence of diet in the etiopathogenesis and management of IBD.

Human health in relation to exposure to solar ultraviolet radiation under changing stratospheric ozone and climate

The Montreal Protocol has limited increases in the UV-B (280-315 nm) radiation reaching the Earth's surface as a result of depletion of stratospheric ozone. Nevertheless, the incidence of skin cancers continues to increase in most light-skinned populations, probably due mainly to risky sun exposure behaviour. In locations with strong sun protection programs of long duration, incidence is now reducing in younger age groups. Changes in the epidemiology of UV-induced eye diseases are less clear, due to a lack of data. Exposure to UV radiation plays a role in the development of cataracts, pterygium and possibly age-related macular degeneration; these are major causes of visual impairment world-wide. Photodermatoses and phototoxic reactions to drugs are not uncommon; management of the latter includes recognition of the risks by the prescribing physician. Exposure to UV radiation has benefits for health through the production of vitamin D in the skin and modulation of immune function. The latter has benefits for skin diseases such as psoriasis and possibly for systemic autoimmune diseases such as multiple sclerosis. The health risks of sun exposure can be mitigated through appropriate sun protection, such as clothing with both good UV-blocking characteristics and adequate skin coverage, sunglasses, shade, and sunscreen. New sunscreen preparations provide protection against a broader spectrum of solar radiation, but it is not clear that this has benefits for health. Gaps in knowledge make it difficult to derive evidence-based sun protection advice that balances the risks and benefits of sun exposure.

Low Sun Exposure and Vitamin D Deficiency as Risk Factors for Inflammatory Bowel Disease, With a Focus on Childhood Onset

The incidence and prevalence of inflammatory bowel disease (IBD) are increasing worldwide. Some ecological studies show increasing incidence with increasing latitude. Ambient ultraviolet radiation varies inversely with latitude, and sun exposure of the skin is a major source of vitamin D. Vitamin D deficiency is common in patients with IBD. Sun exposure and vitamin D have immune effects that could plausibly reduce, or be protective for, IBD. One quarter of new IBD cases are diagnosed in childhood or adolescence, but most research is for adult-onset IBD. Here, we review the evidence for low sun exposure and/or vitamin D deficiency as risk factors for IBD, focusing where possible on pediatric IBD, where effects of environmental exposures may be clearer. The literature provides some evidence of a latitude gradient of IBD incidence, and evidence for seasonal patterns of timing of birth or disease onset is inconsistent. High prevalence of vitamin D deficiency occurs in people with IBD, but cannot be interpreted as being a causal risk factor. Evidence of vitamin D supplementation affecting disease activity is limited. Further research on predisease sun exposure and well-designed supplementation studies are required to elucidate whether these potentially modifiable exposures are indeed risk factors for IBD.

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.

Solar radiation is inversely associated with inflammatory bowel disease admissions

OBJECTIVE

To explore the associations between latitude and solar radiation with inflammatory bowel disease admission rates in Chile, the country with the largest variation in solar radiation in the world.

PATIENTS AND METHODS

This is an ecological study, which included data on all hospital-admitted population for inflammatory bowel disease between 2001 and 2012, according to different latitudes and solar radiation exposures in Chile. The data were acquired from the national hospital discharge database from the Department of Health Statistics and Information of the Chilean Ministry of Health.

RESULTS

Between 2001 and 2012 there were 12,869 admissions due to inflammatory bowel disease (69% ulcerative colitis, 31% Crohn's disease). Median age was 36 years (IQR: 25-51); 57% were female. The national inflammatory bowel disease admission rate was 6.52 (95% CI: 6.40-6.63) per 100,000 inhabitants with increasing rates over the 12-year period. In terms of latitude, the highest admission rates for pediatric ulcerative colitis and Crohn's disease, as well as adult ulcerative colitis, were observed in the southernmost region with lowest annual solar radiation. Linear regression analysis showed that regional solar radiation was inversely associated with inflammatory bowel disease admissions in Chile (β: -.44, p = .03).

CONCLUSIONS

Regional solar radiation was inversely associated with inflammatory bowel disease admission rates in Chile; inflammatory bowel disease admissions were highest in the southernmost region with lowest solar radiation. Our results support the potential role of vitamin D deficiency on inflammatory bowel disease flares.

Serum Cytokine Profiles in Children with Crohn's Disease

Crohn's disease (CD) is a chronic inflammatory bowel disease that can be diagnosed at any age. There are two major patient groups based on diagnosis of this disease, before or after the age of 20 (juvenile/adolescent or adult), with disease progression in adults usually milder than in juvenile CD patients. Immune mechanisms have been suggested to play an important role in CD pathogenesis, with cytokines governing the development of the immune response. Upregulation of inflammatory cytokines in serum of juvenile and adult CD patients has been documented; still little is known about age-dependent differences in serum cytokine profiles of CD patients. We applied multiplex technology to analyze serum levels of 12 cytokines in juveniles and adults. We show that during the acute stage of the disease all CD patients have high serum levels of CXCL10, which remains upregulated during remission. Increased serum levels of TNF-α and IL-6 during the acute stage was characteristic of juvenile CD patients, whereas adult CD patients had upregulated levels of GM-CSF and IFN-γ. Taken together, these results demonstrate age-dependent differences in cytokine profiles, which may affect the pathogenesis of CD in patients at different ages of disease onset.

Progress in Our Understanding of the Gut Microbiome: Implications for the Clinician

The investigation of the role of the microbial communities of our gastrointestinal tract (microbiota) has accelerated dramatically in recent years thanks to rapid developments in the technologies that allow us to fully enumerate and evaluate the full complement of bacterial species and strains that normally inhabit the gut. Laboratory studies in a range of inventive animal models continue to provide insights into the role of the microbiota in health and to generate plausible hypotheses relating to its potential involvement in the pathogenesis of human disease. Studies of the composition of human gut microbiota continue to accumulate but their interpretation needs to be tempered by an appreciation of the limitations of single-point-in-time studies of fecal samples from small study populations. Nevertheless, clinically important examples of a central role for microbiota-host interactions in disease pathogenesis have emerged and many more have been postulated but await confirmation in appropriately powered and conducted studies.

Perinatal vitamin D levels are not associated with later risk of developing pediatric-onset inflammatory bowel disease: a Danish case-cohort study

Objective Basic and epidemiologic studies on inflammatory bowel disease (IBD) have suggested an association between vitamin D and IBD risk. Though, the literature on IBD - especially pediatric-onset IBD - and vitamin D is still in its cradle. We therefore wanted to examine if levels of 25(OH)D at birth were associated with increased risk of developing pediatric-onset IBD. Material and methods A case-cohort study composed of cases diagnosed with Crohn's disease, ulcerative colitis or indeterminate/unclassified colitis and healthy controls. Cases and controls were matched on date of birth and were born in the period 1981-2004. Cases were diagnosed before the age of 18 years. The concentration of 25(OH)D was assessed from neonatal dried blood spots using a highly sensitive liquid chromatography tandem mass spectrometry. Odds ratios (OR) were calculated using conditional logistic regression and two-way ANOVA were used to test for season and birth year 25(OH)D variations. A total of 384 matched pairs were included in the statistical analyses. Results No significant association were found between levels of 25(OH)D and IBD risk in the adjusted model (OR [95% CI] (per 25 nmol/L increase), 1.12 [0.88; 1.42], p = 0.35). 25(OH)D levels were found to fluctuate significantly with season (p < 0.001) and year (p < 0.001). Median/Q1-Q3 values for 25(OH)D were 27.1/16.5-39.5 nmol/L for cases and 25.7/16.1-39.4 nmol/L for controls. Conclusion Our study do not suggest that a window of vulnerability exist around time of birth in regards to 25(OH)D levels and later pediatric-onset IBD risk.

Environmental risk factors for inflammatory bowel diseases: Evidence based literature review

AIM: Advances in genetics and immunology have contributed to the current understanding of the pathogenesis of inflammatory bowel diseases (IBD).

METHODS: The current opinion on the pathogenesis of IBD suggests that genetically susceptible individuals develop intolerance to dysregulated gut microflora (dysbiosis) and chronic inflammation develops as a result of environmental insults. Environmental exposures are innumerable with varying effects during the life course of individuals with IBD. Studying the relationship between environmental factors and IBD may provide the missing link to increasing our understanding of the etiology and increased incidence of IBD in recent years with implications for prevention, diagnosis, and treatment. Environmental factors are heterogeneous and genetic predisposition, immune dysregulation, or dysbiosis do not lead to the development of IBD in isolation.

RESULTS: Current challenges in the study of environmental factors and IBD are how to effectively translate promising results from experimental studies to humans in order to develop models that incorporate the complex interactions between the environment, genetics, immunology, and gut microbiota, and limited high quality interventional studies assessing the effect of modifying environmental factors on the natural history and patient outcomes in IBD.

CONCLUSION: This article critically reviews the current evidence on environmental risk factors for IBD and proposes directions for future research.

Effect of vitamin D supplementation on inflammation: protocol for a systematic review

INTRODUCTION

The extraskeletal role of vitamin D is being increasingly recognised. This has important clinical implications, as vitamin D deficiency has reached epidemic proportions worldwide. Vitamin D has proposed anti-inflammatory properties, yet the role of vitamin D supplementation in reducing inflammation remains largely unknown. The purpose of this review is to investigate the impact of vitamin D supplementation on inflammation, and to identify relevant knowledge gaps in the field.

METHODS AND ANALYSIS

Medline, CINAHL, EMBASE and All EBM will be systematically searched for randomised controlled trials (RCTs) and systematic reviews of RCTs, comparing vitamin D supplementation with placebo, usual care or other pharmacological or non-pharmacological interventions. One reviewer will assess articles for eligibility according to prespecified selection criteria, after which 2 independent reviewers will perform data extraction and quality appraisal. Meta-analyses will be conducted where appropriate.

ETHICS AND DISSEMINATION

Formal ethical approval is not required as no primary data is collected. This systematic review will identify potential clinical implications of vitamin D deficiency and supplementation, and will be disseminated through a peer-reviewed publication and at conference meetings, to inform future research on the efficacy of vitamin D supplementation for inflammation and inflammatory diseases.

PROSPERO REGISTRATION NUMBER

CRD42016037104.

Microbiome-Epigenome Interactions and the Environmental Origins of Inflammatory Bowel Diseases

The incidence of pediatric inflammatory bowel disease (IBD), which includes Crohn disease and ulcerative colitis, has risen alarmingly in the Western and developing world in recent decades. Epidemiologic (including monozygotic twin and migrant) studies highlight the substantial role of environment and nutrition in IBD etiology. Here we review the literature supporting the developmental and environmental origins hypothesis of IBD. We also provide a detailed exploration of how the human microbiome and epigenome (primarily through DNA methylation) may be important elements in the developmental origins of IBD in both children and adults.