Inflammatory bowel disease (IBD) is a heterogeneous group of diseases, comprised of ulcerative colitis (UC) and Crohn’s disease (CD), where patients suffer from chronic inflammation in the gastrointestinal (GI) tract. The pathogenesis of IBD is complex and involves the interaction of various components: genetic susceptibility, immune dysregulation, environmental exposures, and gut microbiota dysbiosis. This multifactorial interplay underlines the importance of identifying and modifying potential risk factors for developing IBD. CD and UC share some similarities and differences in their landscape of clinical and endoscopic findings, but more evidence is currently available for strategies to reduce the risk and prevent UC compared to CD. However, the similarities between these diseases can be helpful in implementing ulcerative colitis preventive measures as a hint to foster future Crohn’s disease prevention, as long as societies are calling for additional efforts in that direction. The first prevention steps should start from our lifestyle and dietary habits: the "Hygiene Hypothesis" proposed that our adoptive immunity would be shaped by the interactions between the host and the environment. Dietary antigens would play a critical role in shaping the host immune response, suggesting that dietary counseling strategies might have a role in the prevention of immune-mediated disorders. Despite being widely proposed in the literature, the association between lifestyle/diet and IBD pathogenesis remains unclear. This review aims to provide a comprehensive overview of the current knowledge and the potential role of IBD preventive programs by using dietary habits and lifestyle modifications.
2.1. Types of Inflammatory Bowel Disease
Till now, the pathogenesis of inflammatory bowel diseases (IBD), which encompasses Crohn’s disease (CD) and ulcerative colitis (UC), has not yet been worked out. It is demonstrated that the pathogenesis of IBD is a result of the interaction among three aspects, including genetic predisposition, immune responses, and environmental factors. In developed countries, the prevalence of IBD is higher than in developing countries. The etiology of IBD occurrence, which is considerably more common in developed countries, is more important compared with others in terms of genomics, molecular level research, and commercial interests. According to twin studies, it was shown that environmental factors might play an important role in the pathogenesis of IBD as it was stated that there should be genes to develop and alter the situation. In recent years, rapid development in research has led us to clearly understand genes due to the genome project. Furthermore, GWAS performed for Mendelian complex IBD and other research showed more than 163 loci involved with IBD. Almost a third of that genetic expression is affected by the relationship. 10 genes were identified at the Mendelian IBD locus. NOD2/CARD15, which has been investigated more than any other segregation, is linked to CD with LRRH, and some say the gene can be associated with UC. Actually, a genetic effect is not enough to define the differences of the disease. Environmental factors can be strong modifiers of the genetic disease risk. There is much data regarding the role of environmental factors in the pathogenesis of IBD. Studies about environmental factors related to IBD ranged from very simple questions, such as diet questions, to studies of smokers and IBD. Frequent consumption of fast food is positively correlated with IBD. A diversified and resourceful diet is protective according to most of the studies. Beaches saturated dioxide and zinc is negatively related to IBD in the diet. Results suggest that a high fiber diet may have a protective effect against IBD.
2.2. Causes and Symptoms
Increasing evidence suggests that environmental factors, including diet, have a great impact on the susceptibility and severity of Crohn's disease (CD) and ulcerative colitis (UC). An individual's diet is an important factor, particularly in the Western world, and altered dietary intake is considered to correlate with an increasing incidence of both CD and UC. Diet exerts its effect on the gastrointestinal mucosa, gut permeability, and the gut microbiota and subsequently affects innate and adaptive immune responses which are of great interest in the pathogenesis of IBD. Lifestyle is a combination of social, mental, and physical aspects and encompasses how people live and what they choose to eat, and also includes modifiable and non-modifiable factors. In the etiology and pathogenesis of IBD, the interplay between the environment and immune system is crucial. The number of individuals developing IBD is on the rise, and currently, the incidence is 400 cases per 100,000 in Northern Europe and 400 cases per 100,000 in the United States.
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