CAN AN UNHEALTHY DIET CAUSE INFLAMMATORY BOWEL DISEASE?
Inflammatory bowel disease (IBD) is a chronic relapsing condition presenting as inflammation of gut mucosa.
Crohn’s disease (CD) presents with transmural skip lesions at any point in the GI tract. In contrast, ulcerative colitis (UC) is a continuous inflammation of the large colon’s mucosal layer only.
Both conditions have suspected dietary etiology. Therefore this article will look at the evidence to date of whether the diet is implicated in IBD development.
The rates of IBD have been increasing over recent years. It now affects 0.5% of the population leading to the suspicion that this increase results from an environmental factor.
Changes in diagnosis rates are reported to be too fast to be purely caused by genetic composition changes. An example of this is the increase in Crohn’s disease in countries such as Japan, notable as a culture that has changed its dietary pat-terns to reflect western diets, which has led to the diet being reported as a possible factor in CD development.
Also, migrants from low incidence areas to high incidence have an increased risk of developing Inflammatory bowel disease.
However, we live in interesting times, and evidence and theories are growing of genetic factors implicated. An area of rapid development is investigating how natural gut flora changes produce an individual’s propensity to develop the disease.
Identifying dietary factors that affect Inflammatory bowel disease development is a huge challenge. Observational prospective studies require large study groups to ensure adequate power, and they are expensive as a result.
Retrospective analysis can have recall bias in a patient group that may be experiencing malnutrition due to diagnosed disease or IBD patients who may experience a sharper focus on a diet compared with a control population.
Clinical experience has shown that patients will understandably self regulate their diet when they suspect that diet is influencing symptoms to ameliorate diarrhea, bloating, and pain.
Reduction of intake and exclusion of food groups appear commonly in IBD.
This situation doesn’t help when developing studies to research dietary causes of IBD. Still, you can empathize with why patients make these changes, as symptoms significantly affect the quality of life.
The best data comes from studying pre-diagnosis diet; in other words, prospective studies. There is a paucity of data available in this area. However, a large multi-centered trial showed that no association was found between diet and UC for men and women.
It has been suggested that heterogeneity due to multi-centered design might have influenced the results, and a marginally positive association was found with the total polyunsaturated fatty acid intake.
It is difficult to recommend that a pre-diagnosis diet doesn’t affect the risk of developing UC on evidence from one study alone. This study has nothing to add to theories of dietary intake and CD risk.
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