Tan Kok-Yang, Seow-Choen Francis
World J Gastroenterol. 2007 Aug 21;13(31):4161-7. doi: 10.3748/wjg.v13.i31.4161.
Whilst fruits and vegetables are an essential part of our dietary intake, the role of fiber in the prevention of colorectal diseases remains controversial. The main feature of a high-fiber diet is its poor digestibility. Soluble fiber like pectins, guar and ispaghula produce viscous solutions in the gastrointestinal tract delaying small bowel absorption and transit. Insoluble fiber, on the other hand, pass largely unaltered through the gut. The more fiber is ingested, the more stools will have to be passed. Fermentation in the intestines results in build up of large amounts of gases in the colon. This article reviews the physiology of ingestion of fiber and defecation. It also looks into the impact of dietary fiber on various colorectal diseases. A strong case cannot be made for a protective effect of dietary fiber against colorectal polyp or cancer. Neither has fiber been found to be useful in chronic constipation and irritable bowel syndrome. It is also not useful in the treatment of perianal conditions. The fiber deficit - diverticulosis theory should also be challenged. The authors urge clinicians to keep an open mind about fiber. One must be aware of the truths and myths about fiber before recommending it.
虽然水果和蔬菜是我们饮食摄入的重要组成部分，但纤维在预防结直肠疾病中的作用仍存在争议。高纤维饮食的主要特点是其消化性差。像果胶、瓜尔豆胶和卵叶车前子这样的可溶性纤维在胃肠道中产生粘性溶液，延迟小肠吸收和转运。另一方面，不溶性纤维在很大程度上未经改变地通过肠道。摄入的纤维越多，需要排出的粪便就越多。肠道发酵会导致结肠中积聚大量气体。本文回顾了纤维摄入和排便的生理学。它还研究了膳食纤维对各种结直肠疾病的影响。膳食纤维对结直肠息肉或癌症的保护作用尚无确凿证据。在慢性便秘和肠易激综合征中，纤维也未被发现有用。它在肛周疾病的治疗中也没有用。纤维缺乏——憩室病理论也应受到质疑。作者敦促临床医生对纤维保持开放的态度。在推荐纤维之前，必须了解关于纤维的真相和误解。
