NUTRITION HOTLINE
By Casey Brown, RD
QUESTION: I am interested in going vegan, but I have IBS. I?m not sure what I would be able to eat if I went vegan?
A.R., via email
ANSWER: Irritable bowel syndrome (IBS) is a chronic condition affecting up to 15% of the population.1 Those with IBS have symptoms of abdominal pain and changes in bowel habits, including diarrhea and/or constipation. IBS has no clear cause nor is there any single test to diagnose it.1
Treatment includes a combination of lifestyle, dietary, and pharmaceutical approaches. The primary dietary approach to treating IBS includes a low FODMAP diet. A low FODMAP diet limits the amount of foods that contain fermentable sugars and sugar alcohols. Foods limited or omitted include wheat products, beans, lentils, dairy products, and certain fruits and vegetables.
Some studies show that this diet can reduce symptoms in 50-80% of patients.2 However, a recent meta-analysis (a technique in which results from a number of studies are combined) found limited evidence to support use of a low FODMAP diet.3
Wheat, vegetables, and beans are common staples for a vegan diet, so it might seem daunting to try a vegan diet if you have IBS.
IBS is an individualized condition. Items that are tolerated do not need to be restricted and will vary from person to person. Typically, high-FODMAP foods are eliminated for 2-6 weeks. Individuals then reintroduce foods one at a time while keeping a food journal to record food/beverage intake and the type, timing, and severity of the symptom(s) they experience, if any. Foods that are tolerated without symptoms can be added back into the diet. Foods that trigger IBS symptoms are excluded.
Since beans, wheat, and lentils are protein sources, protein intake may be a concern on a low FODMAP vegan diet. Allowed vegan sources of protein include tempeh, tofu, quinoa, oatmeal, certain nuts, soymilk made from soy protein (not whole soybeans), and limited amounts of lentils or chickpeas. Other low FODMAP foods include gluten-free breads, pastas, and cereals; tomatoes; spinach; potatoes; berries; and cantaloupe.
A low FODMAP diet can be effective in reducing symptoms, although more research is needed. Consulting with a registered dietitian can ensure that you meet your nutrient needs.
REFERENCES
1 Wald, A. Treatment of irritable bowel syndrome in adults. UpToDate. May 23, 2019. www.uptodate.com/contents/treatment-of-irritable-bowel-syndrome-in-adults
2 Phillips W, Walker J. When a registered dietitian becomes the patient: translating the science of the low FODMAP diet to daily living. Practical Gastroenterology. 2018;175:20-37.
3 Dionne J, Ford AC, Yuan Y, et al. A systematic review and meta-analysis evaluating the efficacy of a gluten-free diet and a low FODMAP diet in treating symptoms of irritable bowel syndrome. Am J Gastroenterol. 2018;113:1290-1300.
