饮食在炎症性肠病发病机制中的作用

Nature Reviews Gastroenterology & Hepatologyvolume  (2018)

doi: 10.1038/s41575-018-0022-9

The role of diet in the aetiopathogenesis of inflammatory bowel disease

Nature Reviews Gastroenterology and Hepatology上发表的一篇重要综述，介绍了饮食因素对IBD的影响以及背后的机制，推荐阅读。

论文摘要

Crohn’s disease and ulcerative colitis, collectively known as IBD, are chronic inflammatory disorders of the gastrointestinal tract that have an increasing incidence1 and affect over one million individuals in the US and 2.5 million individuals in Europe2,3, resulting in sub- stantial morbidity4, health-care expenses and loss of productivity in the work environment5,6. Although the pathophysiology of IBD is largely unknown, it is thought to be related to an inappropriate immune response to commensal bacteria in genetically susceptible hosts (Fig. 1). A role for genetic risk factors in the develop- ment of IBD has been highlighted by the identification of >200 susceptibility loci in genome-wide association studies (GWAS)7,8. In addition to the genetic con- tribution to IBD pathophysiology, environmental factors also seem to substantially contribute to both the development and progression of IBD. For instance, twin studies have demonstrated a <50% concordance in the development of Crohn’s disease and ulcerative colitis9,10. In addition, epidemiological studies have confirmed the rapid increase in the incidence of IBD in the US and developing countries that have witnessed a dramatic Westernization of lifestyle, with the worldwide prevalence of the disease having surpassed 0.3% at the turn of the twenty-first century1,11. Moreover, studies have shown that the incidence of IBD in immigrants to developed countries exceeds that of individuals from their country of origin12–15. 

Among environmental factors, diet is widely thought to have a pivotal role in the development of IBD. Although the exact pathophysiological mechanisms remain unknown, several plausible explanations have been proposed (Fig. 2). First, diet has a key role in defin- ing the composition of the human gut microbiota and, consequently, that of microbial metabolites16. Second, food and nutrients associated with a Western diet — characterized by high intakes of red meat, sugary des- serts, high-fat foods and refined grains — have been linked to increased mucosal inflammation as measured by stool calprotectin levels in human subjects17. Last, animal studies have demonstrated that dietary compo- sition regulates mucosal barrier function, a crucial factor in the pathogenesis of IBD18,19. Despite these data, human observational studies investigating the role of diet in IBD have yielded contradictory and inconclusive results. 

In this Review, we discuss the available data on the role of diet in the pathogenesis of IBD with a focus on epidemiological, gene–environment interaction, intervention, gut microbiome and animal studies. We also highlight the limitations of prior studies, particu- larly epidemiological and gene–environment studies, and review future directions that build upon these preliminary studies. 

实验综述

① 西式饮食（红肉、加工食品、精制糖、饱和脂肪）增加IBD的风险；

② 可能的机制包括引起肠道菌群失调，破坏肠道屏障功能，改变促炎症性Th17细胞与调节性T细胞（Treg）的比例；

③ 地中海饮食（摄入大量水果与蔬菜、全谷物及海鲜）增加肠道菌群多样性，维持完整的肠道屏障功能，平衡Th17细胞与Treg的比例；

④ 在一些前瞻性研究中发现，亚油酸、血红素铁等与IBD风险增加相关，DHA、膳食纤维、锌、钾、牛奶等与IBD风险降低相关。