The FODMAP diet for irritable bowel syndrome

Physicians have often been challenged by the lack of available treatment options for irritable bowel syndrome (IBS). The Council on Health Promotion’s Nutrition Committee would like to alert you to an emerging dietary approach to potentially resolve IBS symptoms prior to initiating medications. Emerging evidence suggests that symptoms of IBS may be partly due to malabsorption of short-chain carbohydrates. Enter the low FODMAP diet—a potential IBS dietary management tool.

IBS is a diagnosis of exclusion, and organic causes need to be ruled out in addition to tests run for celiac disease prior to initiation of restricted diets. It is established that foods act as symptom triggers rather than causal agents of IBS. Symptoms vary from person to person and can include gas, bloating, abdominal pain/discomfort, constipation, diarrhea, indigestion, or a combination.

It is recommended that foods in the subgroups of fermentable carbohydrates be eliminated from the diet for 6 to 8 weeks. The elimination phase is followed by a careful and sequential trial of foods from each subgroup to assess symptoms and tolerances.

The most commonly documented successes have resulted from elimination of fructose, lactose, or both.[1] While reviewing the role of FODMAPs in patients with IBS, we noted the potential association between lowered Lactobacillus and Bifidobacterium flora and increased IBS.[1]

The guidance and expertise of a registered dietitian is the first line of treatment with this dietary approach to prevent the patient’s diet from becoming overly restrictive. The FODMAP diet can be complicated, and without proper guidance can result in significant nutritional deficiencies. Family physicians should refer patients to registered dietitians, who can provide appropriate counseling and nutrition advice related to the FODMAP diet and other IBS dietary management tools.

Registered dietitians differ from other unregulated nutrition practitioners. Unlike registered holistic nutritionists, certified nutritional practitioners, and registered nutritional consultants, registered dietitians are regulated by the College of Dietitians of British Columbia under the Health Professions Act. Referral to a registered dietitian ensures that your patient will be counseled by a health professional with at least 5 years of training, including an accredited internship, and—as with physicians, nurses, and other qualified health care professionals—will be accountable to a regulatory body.

The FODMAP diet is gaining popularity and patients are sure to ask about it. While this article seeks to provide a basic introduction to a complex issue, patients will need further validated nutritional support, ideally from a registered dietician. Practical tools, resources, and guidance on understanding and implementing the FODMAP diet are also available from:

•    Monash University in Melbourne, Australia, which is leading the way in designing practical tools and guidance for the low FODMAP diet. They have developed apps, low FODMAP food lists, resources, research updates, and FAQs (www.med.monash.edu/cecs/gastro/fodmap).

•    The Canadian Digestive Health Foundation, which provides a three-page synopsis titled “Understanding FODMAPs.” The handout includes simplified tables outlining low and high FODMAP foods (http://cdhf.ca/bank/document_en/32-fodmaps.pdf).

—Kathleen Cadenhead, MD
—Amanda Lau, MD
—Mary Hinchliffe, MD
—Margo Sweeny, MD
—Tanis Mihalynuk, RD
Nutrition Committee

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This article is the opinion of the Council on Health Promotion and has not been peer reviewed by the BCMJ Editorial Board.

References

1.    Mansueto P, Seidita A, D’Alcamo A, et al. Role of FODMAPs in patients with irritable bowel syndrome: A review. Nutr Clin Pract 2015;pii:0884533615569886. E-published ahead of print.