Foods may cause irritable bowel syndrome (IBS) symptoms: In the U.S., most doctors have been, and continue to be, skeptical that foods cause symptoms of (IBS) and elimination of specific foods can improve these symptoms. This is despite almost 70% of people diagnosed as having IBS reporting 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.
Food intolerance testing and elimination diet based on IgG antibodies may be beneficial: 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.
Irritable bowel syndrome (IBS) is very commonly diagnosed in adults: No diagnostic tests can confirm IBS. It is a diagnosis of exclusion. It is a syndrome, that is, a collection of symptoms that cannot be explained by other diseases resulting in the diagnosis of IBS. Common missed diagnoses that are blamed on IBS include lactose intolerance, Celiac disease, gluten sensitivity or gluten intolerance, colitis, Crohn's disease, parasite infections such as giardia, bacterial overgrowth in the intestine or alterations in gut bacteria levels and types (dysbiosis), food allergies, food intolerance, and food hypersensitivity.
Celiac disease, colitis and Crohn's disease should be excluded before diagnosing IBS: Celiac disease, colitis and Crohn's disease can be diagnosed or excluded by blood tests, stool tests, and biopsies of the intestine. Food allergy, intolerance and sensitivity are not only more difficult to confirm or exclude but frequently missed because of limitations of blood tests, stool tests, allergy skin tests and biopsies. Adverse food reactions have to be considered as a potential cause of the symptoms attributed to IBS.
There are common foods that cause adverse food reactions: Common foods reported by IBS sufferers, whose symptoms improve with elimination, 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 (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).
Individual specific and food-specific elimination diets are based on a variety of tests and a food-symptom diet diary: Elimination diets based on the common foods causing allergic reactions and non-allergic food reactions have been used for quite some time and are often prescribed with or without a food symptom diet diary. Interestingly, to my knowledge, no one has looked at approaching these people and their adverse food reactions individually, based on tests for Celiac disease, gluten intolerance or sensitivity (elevated blood gliadin IgA or IgG antibodies and/or stool gliadin IgA antibody without diagnostic blood tests or biopsy for Celiac), casein intolerance (stool IgA anti-casein antibody or blood IgG antibody), oral allergy syndrome (OAS) history and thorough food allergy testing (skin prick testing, IgE RAST or CAP RAST tests, intradermal skin testing or patch skin testing).
Specific food elimination diet trials based on such information (see the table at www.thefooddoc.com) has been helpful in my experience. Food-pollen cross reaction in OAS is well documented. A diet symptom diary combined with specific food elimination based on results of food allergy tests, food intolerance of food sensitivity tests, and known pollen allergies should be considered as a possible approach to elimination diet. This should not exclude evaluation for and treatment of established Celiac disease, lactose intolerance, dysbiosis, colitis or Crohn's disease.
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.