Patient - Irritable Bowel Syndrome (IBS) Research Articles Overview

Overview

This section will highlight quality research on irritable bowel syndrome, with an emphasis on complementary and innovative therapies. Each will have a short annotation and a link whenever possible to the citation in PubMed’s Medline Database or the full text of the article.

British Medical Journal (BMJ) articles on IBS
Presents a series of articles on IBS published in BMJ from 1999-2004.

Spiller RC. "Potential future therapies for irritable bowel syndrome: will disease modifying therapy as opposed to symptomatic control become a reality?" Gastroenterology Clinics of North America. 34(2):337-54, 2005.
Irritable bowel syndrome is most likely to resolve quickly in patients with a short history of IBS, acute onset (possibly after infection), absence of psychological disorders, and resolution of chronic life stressors. Dietary changes, which often involve excluding dairy and wheat products, are successful in some patients. In one clinical trial, anti-inflammatory treatments given to post-infective IBS patients showed no benefit. Probiotics may have benefit in altering bacterial flora and as anti-inflammatory agents, but further trials are needed. Psychological treatments may produce long-lasting responses. This includes relaxation therapy and psychotherapy, which has been shown to have long-term benefit particularly in those with overt psychological distress. Hypnotherapy has also been shown to be effective in randomized placebo controlled trials and has a sustained effect.

Causes

Barbara G, De Giorgio R, Stanghellini V, Cremon C, et al. "New pathophysiological mechanisms in irritable bowel syndrome." Alimentary and Pharmacological Therapeutics. 20 Suppl 2:1-9, 2004.
Irritable bowel syndrome (IBS) is characterized by abdominal pain and inconsistent bowel habits. Changes in gastrointestinal motor function, increased perception of gut stimuli and psychosocial factors are thought to be major contributors to symptoms. In recent years, several additional factors have been identified. Reduced ability to expel intestinal gas which causes gas trapping and bowel distension may contribute to abdominal discomfort/pain and bloating. An acute gastrointestinal infection is now a recognized causative factor for symptom development in some IBS patients (i.e. post-infectious IBS). Low-grade inflammation and activation of mast cells near nerves in the lining of the colon may also contribute to the frequency and severity of abdominal pain in post-infectious and non-specific IBS. These new factors may aid in forming a better understanding of IBS and in the development of new therapies.

Collins SM, Piche T, Rampal P. "The putative role of inflammation in the irritable bowel syndrome." Gut. 49(6):743-745, 2001.
Animal studies have shown that mild inflammatory stimuli can disturb the sensory-motor system of the gut and under certain conditions these disturbances may last after resolution of the inflammatory response. This process may underlie the development of IBS in patients recovering from acute gastroenteritis or a relapse of inflammatory bowel disease. The extent to which inflammation contributes to IBS in the remainder of IBS patients remains unclear but there are data implicating the activation of the immune system in patients with severe IBS. Further research should seek to identify markers of inflammatory-based IBS and explore new therapeutic options aimed at suppressing the ongoing low-grade inflammatory/immune response.

Horwitz BJ and Fisher RS. "Current concepts: the irritable bowel syndrome." The New England Journal of Medicine. 344(24):1846-1850, 2001.
This review article covers basic information on IBS including possible causes such as visceral hypersensitivity, psychosocial factors, neurotransmitter imbalance, infection and inflammation. It also discusses the diagnosis of IBS and treatment options including diet, medications, relaxation, hypnosis, cognitive behavioral therapy and psychotherapy.

Lin HC. "Small intestinal bacterial overgrowth: a framework for understanding irritable bowel syndrome." JAMA. 292(7):852-8, 2004.
Irritable bowel syndrome (IBS), which affects 11% to 14% of the population, is a condition with multiple theories of causation. Although no conceptual framework accounts for all the symptoms and observations in IBS, a unifying explanation may exist since 92% of these patients share the symptom of bloating regardless of their predominant complaint. The possibility that small intestinal bacterial overgrowth (SIBO) may explain bloating in IBS is supported by a variety of evidence. The gastrointestinal and immune effects of small intestinal bacterial overgrowth may explain symptoms such as after-meal bloating, altered motility, visceral hypersensitivity, abnormal brain-gut interaction, autonomic nervous system dysfunction, and immune activation.

Rodriguez LAG and Ruigomez A. "Increased risk of irritable bowel syndrome after bacterial gastroenteritis: cohort study." BMJ. 318(7183):565-566, 1999.
Evidence exists of an increased risk of irritable bowel syndrome after an episode of bacterial gastroenteritis. In one study, 12 out of 38 patients presented with bowel dysfunction 1 year after salmonella gastroenteritis. In another study, 386 patients with bacterial gastroenteritis were surveyed 6 months after infection, and 27 (7%) had developed irritable bowel syndrome. The current study included a group of 584,308 subjects in the general population and a group of 318 patients with gastroenteritis. During the 1 year follow up, 2027 (0.3%) subjects in the general population group and 14 (4.4%) in the gastroenteritis group had a diagnosis of irritable bowel syndrome. One hundred and sixty nine subjects (78%) from the random sample of the general population group and 12 (86%) subjects in the gastroenteritis group had confirmed irritable bowel syndrome on the basis of the questionnaire. The relative risk of irritable bowel syndrome was much higher in the gastroenteritis group than in the general population group.

Si JM, Yu YC, Fan YJ, et al. "Intestinal microecology and quality of life in irritable bowel syndrome patients." World Journal of Gastroenterology. 19(12):1802-1805, 2004.
It has been noted that gastroenteritis or dysentery plays a role in the development of irritable bowel syndrome (IBS), and also that antibiotics can increase abdominal symptoms, both of which may be partly due to intestinal flora disorders. The aim of this study was to determine if there is a change in gut flora in IBS patients. Twenty-five IBS patients were recruited, and 25 volunteers were accepted as control. The fecal flora, including Lactobacillus, Bifidobacterium, Bacteroides, C. perfringens Enterobacteriacea and Enterococus, were analyzed. The ratio of Bifidobacterium to Enterobacteriaceae (B/E ratio) in both IBS patients and the control group was determined. In IBS patients, the number of fecal Bifidobacterium was significantly decreased and that of Enterobacteriaceae was significantly increased compared with that in healthy controls. It was concluded that there are intestinal flora disorders in IBS patients, which may be involved in triggering the IBS-like symptoms.

Spiller RC. "Inflammation as a basis for functional GI disorders." Best Practice & Research Clinical Gastroenterology. (4):641-61, 2004.
The term ‘functional diseases’ implies symptoms arising without obvious pathology. However, inflammation often leaves changes in nerves and mucosal tissue that are only apparent using specialized techniques. Approximately 1 out of 10 IBS cases arise after a bout of gastrointestinal infection. Post-infectious IBS is most often the diarrhea-predominant type of IBS. Post inflammatory functional diseases tend to be associated with less psychological abnormalities and have a better outcome than other functional diseases. While there are isolated anecdotal reports of symptom response to anti-inflammatory treatments, larger controlled trials are needed.

Yakoob J, Jafri W, Jafri N, et al. "Irritable bowel syndrome: in search of an etiology: role of Blastocystitis hominis." American Journal of Tropical Medicine & Hygiene. 70(4):383-5, 2004.
This study was designed to examine stool specimens of irritable bowel syndrome (IBS) patients for Blastocystis hominis, a common intestinal parasite. One hundred fifty patients were enrolled, 95 IBS cases and 55 controls. Stool microscopy was positive for B. hominis in 32% (30 of 95) of the cases and 7% (4 of 55) of the controls. Stool culture was positive in 46% (44 of 95) of the cases and 7% (4 of 55) of the controls. Blastocystis hominis was frequently demonstrated in the stool samples of IBS patients; however, its significance in IBS still needs to be investigated. Stool culture has a higher positive yield for B. hominis than stool microscopy.

Complementary/Alternative/Integrative Approaches

Hussain Z, Quigley EM.“Systematic review: Complementary and alternative medicine in the irritable bowel syndrome.” Alimentary Pharmacology & Therapeutics. 23(4):465-71, 2006 Feb 15.
A systematic review of complementary and alternative medical therapies in irritable bowel syndrome was performed. Although many of the clinical studies were small and of poor quality, there is evidence to support efficacy for hypnotherapy, some forms of herbal therapy and certain probiotics in irritable bowel syndrome.

Kiefer D, Ali-Akbarian L. "A brief evidence-based review of two gastrointestinal illnesses: Irritable bowel and leaky gut syndromes. Alternative Therapies in Health & Medicine. 10(3): 22-30, 2004.
This article discusses three complementary therapies that have been shown to be effective in IBS and reviews the research on their use: hypnotherapy, Chinese herbs and probiotics.

Spanier JA, Howden CW, Jones MP. "A systematic review of alternative therapies in the irritable bowel syndrome. Archives of Internal Medicine. 163:265-274, 2003.
A variety of treatments that exist beyond the scope of commonly used therapies for irritable bowel syndrome are reviewed. Interest exists for Traditional Chinese Medicine and psychological therapies, but further well-designed trials are needed. Oral cromolyn sodium may be useful in chronic unexplained diarrhea and appears as effective as and safer than elimination diets. The roles of lactose and fructose intolerance remain poorly understood. Alterations of intestinal flora may play a role in irritable bowel syndrome, but supporting evidence for bacterial overgrowth or probiotic therapy is lacking.