In the U.S., most doctors have been and continue to be skeptical that foods cause symptoms of irritable bowel syndrome (IBS) and elimination of specific foods can improve these symptoms. This is despite almost 70% of people diagnosed as having IBS report symptoms related to specific foods. There is accumulating evidence, though still criticized because of limitations of studies that make it difficult to prove, that specific foods may be the cause of symptoms in many people labeled as having IBS.
Atkinson et.al (Gut, 2004) randomized people to either an elimination diet based on elevated IgG antibody levels (YorkTest Laboratories) for specific foods or a sham diet. Those who avoided specific foods based on their IgG antibody tests had improvement in IBS symptoms (10-26% reduction) and global rating of quality of life significantly improved. Re-introducing foods for which they tested positive resulted in worsening. Zar et.al. (Am J Gastro, 2005) reported significant improvement of IBS symptoms such as pain, bloating, and alterations in bowel habits based on six month elimination of elevated food-specific IgG4 antibodies in 25 people.
Common foods reported by IBS sufferers are wheat, barley, and rye (gluten); dairy including cow's milk protein casein) and/or lactose (milk sugar); the legumes peanut and soy; yeast used to bake or brew foods; corn; shellfish and fish; nuts like almond, Brazil nut, cashew, and walnut; fruits apple, orange, and strawberry; vegetables celery, cabbage, and lettuce; the meats pork, beef, and chicken; and nightshades potato and tomato. Elimination of all of these foods in all people with IBS symptoms without specific testing or a food symptom diet diary is nearly impossible.
Interestingly, to my knowledge no one has looked at individual food-specific diet based on testing for Celiac disease, gluten intolerance or sensitivity (elevated gliadin antibodies in blood and/or stool with normal or non-diagnostic biopsy for Celiac), casein intolerance (elevated stool IgA anti-casein antibody and/or blood IgG antibody), oral allergy syndrome (OAS) history, or positive food and/or pollen allergy testing (skin prick testing, IgE RAST or CAP RAST tests, intradermal skin testing or patch skin testing). I believe it time for a more thorough evaluation for possible food cause of IBS symptoms before accepting that diagnosis and the usual non-dietary treatments.
Bibliography
Atkinson W, Sheldon TA, Shaath N, Whorwell PJ. Food elimination based on IgG antibodies in irritable bowel syndrome:a randomised controlled study. Gut 2004;53:1459-1464.
Choung RS, Talley NJ. Food Allergy and Intolerance in IBS. Gastroenterology & Hepatology October 2006;2(10):757-760.
Zar S, Benson MJ, Kumar D. Food-specific serum IgG4 and IgE titers to common food antigens in irritable bowel syndrome. American Journal Gastroenterology 2005;100:1550-1557.
Zar S, Mincher L, Benson MJ, Kumar D. Food-specific IgG4 antibody guided exclusion diet improves symptoms and rectal compliance in irritable bowel syndrome. Scandinavian Journal of Gastroenterology. 2005;40:800-807.
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