From Medscape Medical News
Irritable Bowel Syndrome: New Dietary Guidelines
Laurie Barclay, MD
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May 15, 2012 — The British Dietetic Association (BDA) has issued evidence-based guidelines for the dietary management of irritable bowel syndrome (IBS) in adults. The new recommendations were published online April 10 and in the June print issue of the Journal of Human Nutrition and Dietetics.
“[IBS] is a chronic and debilitating functional gastrointestinal disorder that affects 9–23% of the population across the world,” write Y.A. McKenzie, MSc, from Nuffield Health the Manor Hospital, Oxford, United Kingdom, and colleagues from the BDA Gastroenterology Specialist Group. “Diet and lifestyle changes are important management strategies. The aim of these guidelines is to systematically review key aspects of the dietary management of IBS, with the aim of providing evidence-based guidelines for use by registered dietitians.”
A guideline development group wrote questions concerning diet and IBS symptom management, such as the role of milk and lactose, nonstarch polysaccharides (NSP), and fermentable carbohydrates in abdominal bloating; use of probiotics; and empirical or elimination diets. To identify pertinent studies, the investigators electronically searched the Cinahl, Cochrane Library, Embase, Medline, Scopus, and Web of Science databases from January 1985 to November 2009.
On the basis of their comprehensive literature search and critical appraisal of 30 studies, the group developed evidence statements, clinical recommendations, good practice points, and research recommendations. The resulting dietetic care pathway followed a logical sequence of treatment, including 3 lines of dietary management:
First-line dietary management: clinical and dietary evaluation and healthy eating and lifestyle management, with some general advice on lactose and NSP.
Second-line dietary management: Advanced dietary interventions to alleviate symptoms resulting from NSP and fermentable carbohydrates, and use of probiotics.
Third-line dietary management: Elimination and empirical diets.
The group also made research recommendations mandating sufficiently powered, well-designed, randomized controlled trials (RCTs).
Specific clinical practice recommendations, and their grade of recommendation, include the following:
To improve IBS symptoms, remove milk and dairy products. When milk sensitivity is suspected and a lactose hydrogen breath test is unavailable or appropriate, attempt a trial period of a low-lactose diet, particularly in individuals in ethnic groups associated with a high prevalence of primary lactase deficiency (D).
Treat individuals in whom lactose hydrogen breath test is positive with a low-lactose diet (D).
When milk is suspected to be a problem food and symptoms do not improve on a low-lactose diet, consider the contribution of other components of milk, such as cow’s milk protein. Consider a milk-free diet or use of an alternative mammalian milk (D).
Avoid dietary supplementation with wheat bran. Individuals with IBS should not increase their wheat bran intake above their usual dietary intake (C).
A 3-month trial of dietary supplementation of ground linseeds is recommended for individuals with constipation-predominant IBS, as symptom improvement may be gradual (D).
Consider reducing intake of fermentable carbohydrates for individuals with IBS and suspected or diagnosed fructose malabsorption (B).
Consider reducing intake of fermentable carbohydrates for individuals with IBS and abdominal bloating, abdominal pain, and/or flatulence (D).
Individual tolerance levels to fermentable carbohydrates may vary. A planned and systematic challenge of foods high in fermentable carbohydrates can identify both individual tolerance levels and which foods can be reintroduced to the diet (D).
After the above steps, consider probiotics, selecting 1 product at a time and monitoring the effects, as there is considered to be no harm associated with probiotics for individuals with IBS (B).
Each probiotic trial should last a minimum of 4 weeks at the manufacturer’s recommended dose (B).
Particularly for patients with diarrhea-predominant IBS, consider an elimination or empirical diet when food appears to be a trigger for IBS symptoms (D).
If symptoms do not improve within 2 to 4 weeks, the specific foods eliminated are an unlikely cause of IBS symptoms (D).
“These guidelines provide evidence statements, recommendations and practical considerations for dietitians on the effective dietary management of IBS in adults and will improve evidence-based practice,” the authors conclude. The guidelines will also “increase standardisation in clinical practice, thus improving patient outcomes in relation to the dietary management of this disorder.”
“Because much of the evidence is of poor quality and limited by the lack of suitable papers for inclusion, research recommendations were also proposed,” the authors add, stating that future research should involve “[a]dequately powered and well designed RCTs, with long-term follow-up,” and “should focus on the clinical effectiveness and/or safety of dietary treatments using objective symptom assessment and taking into consideration IBS-subtype.”
The General Education Trust of the BDA partly funded this project. All members of the IBS dietetic guideline development group signed conflict-of-interest forms annually during the development of these guidelines.
J Hum Nutr Diet. 2012;25:260-274. Abstract