Ananthakrishnan Ashwin N
Dr. Ananthakrishnan is an Assistant Professor of Medicine in the Division of Gastroenterology at the Massachusetts General Hospital and Harvard Medical School in Boston, Massachusetts.
Gastroenterol Hepatol (N Y). 2013 Jun;9(6):367-74.
Crohn's disease (CD) and ulcerative colitis (UC) are chronic immunologically mediated diseases that often have a relapsing-remitting course in young persons. Genetic-risk polymorphisms explain less than one third of the heritability of disease. Epidemiologic and laboratory data suggest that environmental factors play a significant role in influencing the risk and natural history of disease. Smoking is the most widely and consistently described risk factor. It, however, increases the risk of CD while conferring protection against UC. The gut microbiome is a key component in the development of inflammatory bowel disease (IBD). Several external factors potentially exert an effect by influencing the composition of the gut microbiome or disrupting the intestinal barrier. These external influences include the use of antibiotics or nonsteroidal anti-inflammatory drugs and the presence of enteric infections. Data on diet have been inconsistent, but high fiber intake, particularly of soluble fiber, appears to protect against CD, whereas protein intake may increase disease risk. Vitamin D may also play an important protective role, particularly in patients with CD. Neurobehavioral factors, such as stress and depression, also influence the risk of IBD. Systematic and rigorous studies of environmental exposures in the management of IBD are needed. In particular, studies of whether environmental factors can be modified to reduce the likelihood of relapse or improve patient outcomes would be valuable.
克罗恩病（CD）和溃疡性结肠炎（UC）是慢性免疫介导性疾病，在年轻人中通常呈复发-缓解病程。遗传风险多态性对疾病遗传度的解释不足三分之一。流行病学和实验室数据表明，环境因素在影响疾病风险和自然史方面起着重要作用。吸烟是描述最为广泛且一致的风险因素。然而，它会增加患CD的风险，同时对UC具有保护作用。肠道微生物群是炎症性肠病（IBD）发病的关键组成部分。一些外部因素可能通过影响肠道微生物群的组成或破坏肠道屏障而发挥作用。这些外部影响包括使用抗生素或非甾体抗炎药以及存在肠道感染。关于饮食的数据并不一致，但高纤维摄入，尤其是可溶性纤维的摄入，似乎对CD具有预防作用，而蛋白质摄入可能会增加患病风险。维生素D也可能发挥重要的保护作用，尤其是在CD患者中。神经行为因素，如压力和抑郁，也会影响IBD的风险。需要对IBD管理中的环境暴露进行系统而严谨的研究。特别是，关于是否可以通过改变环境因素来降低复发可能性或改善患者预后的研究将很有价值。
