IBS and Food Allergies

Woman holding a plate of food.
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Due to the fact that the act of eating stimulates the process of digestion, it is hard not to associate your IBS symptoms with the foods that you eat. You may have even wondered whether you have a food allergy or maybe someone has told you that you should go for allergy testing. Here you will learn about what food allergies actually are and what is known about their relationship with IBS.

What Is a Food Allergy?

A person is considered to have a food allergy when their immune system reacts to a food substance that is normally considered harmless.

A food allergy involves an antibody called immunoglobulin E (IgE) which can be measured through a blood test. Food allergies are a pretty rare thing - affecting only up to four percent of adults. Estimates of food allergy in children range from six to eight percent.

Symptoms of a Food Allergy

Symptoms of a food allergy typically occur within two hours of eating the triggering food. Symptoms of a food allergy include:

  • Itching
  • Hives
  • Wheezing
  • Lip swelling
  • Throat tightness
  • Difficulty breathing

Some symptoms of a food allergy can be gastrointesinal in nature:

  • Abdominal pain
  • Diarrhea
  • Nausea
  • Vomiting

Is There a Relationship Between Food Allergies and IBS?

Contrary to popular opinion, the majority of researchers in this area have come to the conclusion that there is no consistent evidence to support the notion that an IgE-mediated food allergy plays a role in IBS. The only possible area where there might be a connection is with a very small group of people who have IBS alongside atopy.

People with atopy have bodies that produce IgE in response to environmental triggers such as dust and pollen, and perhaps food allergens. These individuals tend to experience the classic diseases we associate with allergy - and asthma, eczema (atopic dermatitis), and hay fever (allergic rhinitis). Please keep in mind that research between IBS and atopic disease is only in a very preliminary stage.

Are Food Allergy Tests Worth It?

Food allergy testing for IBS often tests for a different class of antibodies, that of IgG. Unfortunately, there is a lot of controversy as to the accuracy of tests that measure IgG in your blood - and what any results actually mean. Since food allergy is so rare, it may not be worth the investment of your money and time. As always, when in doubt, consult your physician.

What About Food Intolerance?

Just because true food allergies are rare, it does not mean that you are imagining that there may be a connection between some of the foods that you eat and your IBS symptoms. A food intolerance means that your body is having a reaction to a food, but it is not an IgE-mediated allergic reaction.

There are several foods that have been identified in research studies as those that can contribute to unwanted digestive symptoms in a sub-set of people who have IBS:

    In addition to the above group of foods, there are other foods that have a reputation for triggering IBS symptoms, but without hard-core science to confirm such food sensitivities. It is extremely hard to do research in this area, and therefore estimates of the effectiveness of eliminating these foods vary very widely from study to study. Looking at all of such studies as a whole, wheat, milk, and eggs are the most commonly identified as being problematic.

    How to Identify If a Food Is Really a Problem for You?

    The best way to identify if a particular food is contributing to your digestive symptoms is through the use of an elimination diet. This involves tracking what you eat, how you feel, and any other possible contributing factors with a food diary to look to see if a potential trigger can be identified. You would then eliminate that food for a period of time and see what effect that has on your symptoms. If you see an improvement in your symptoms, you may have identified a sensitivity. However, it is essential to re-introduce the food at some point so as to ensure that it was the elimination of that particular food that improved your symptoms, and not some other factor. What you want to watch out for is that you are not needlessly eliminating a food that is not really a trigger for your symptoms, as that could put you at risk for nutritional deficiencies.

    Sources:

    Cuomo, R., et. al. "Irritable bowel syndrome and food interaction" World Journal of Gastroenterology 2014 20:8837–8845.

    El-Salhy, M. & Gundersen, D. "Diet in irritable bowel syndrome" Nutrition Journal 2015 14:36.

    El-Salhy, M., et. al. "Interaction between ingested nutrients and gut endocrine cells in patients with irritable bowel syndrome (Review)" International Journal of Molecular Medicine 2014 34:363–371.

    Hayes, P., Fraher, M. & Quigley, E. "Irritable Bowel Syndrome: The Role of Food in Pathogenesis and Management" Gastroenterology & Hepatology 2014 10: 164–174.

    Mansueto, P., et. al. "Food allergy in irritable bowel syndrome: The case of non-celiac wheat sensitivity" World Journal of Gastroenterology 2015 21:7089–7109.

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