The Science, Evidence, and Practice of Dietary Interventions in Irritable Bowel Syndrome

Brian E. Lacy


Clin Gastroenterol Hepatol. 2015;13(11):1899-1906. 

In This Article

Abstract and Introduction


Irritable bowel syndrome (IBS) is a highly prevalent disorder that is characterized by symptoms of abdominal pain, bloating, constipation, and/or diarrhea. The diagnosis can be made using Rome III criteria or published guidelines after taking a thoughtful history, excluding warning signs, and performing a careful physical examination. Limited testing (ie, complete blood count and C-reactive protein level) may be useful in appropriate patients. A number of pharmacologic options are available, although many patients fail to respond to pharmacologic therapy. Although several IBS diets frequently are recommended, data supporting their use are limited. This article provides a rationale as to why specific diets might improve IBS symptoms and evaluates published trials.


Irritable bowel syndrome (IBS) is the most thoroughly studied functional gastrointestinal disorder.[1] The estimated prevalence of IBS is 9% to 14%; it accounts for approximately 12% of visits to primary care physicians and 28% of referrals to gastroenterologists.[2–5] IBS can develop across a broad range of ages, and economic, social, and ethnic backgrounds.[4,6,7]

The negative impact of IBS on patients' quality of life and the significant economic impact on our health care system is well known.[7–13] This impact highlights the need for more effective IBS treatments because current therapies are not uniformly successful.[14,15] This has led to an interest in dietary interventions for the treatment of IBS, which is quite logical because 60% to 70% of IBS patients report a worsening of symptoms after meals, 50% to 70% report intolerance to various foods, and more than 70% believe that foods cause their symptoms.[16–22] However, despite widespread use, there are limited data supporting the use of specialized diets to treat IBS symptoms. This article briefly reviews the pathophysiologic mechanisms that may explain IBS food-related symptoms and evaluates clinical trials of specialized diets used to treat IBS symptoms. Dietary supplements are not reviewed given the lack of controlled trials; the reader is referred to recent reviews on probiotics and antibiotics.[14,15]