Is Your IBS Really a Food Allergy?

Sometimes you might 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.

Woman holding a plate of food.
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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). While it isn't routinely tested, this antibody can be measured with a blood test.

A food allergy is a pretty rare disorder, affecting only up to 4 percent of adults. Estimates of food allergy prevalence in children range from 6 to 8 percent.

Symptoms of a Food Allergy

The effects 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 gastrointestinal in nature:

  • Abdominal pain
  • Diarrhea
  • Nausea
  • Vomiting

Is There a Relationship Between Food Allergies and IBS?

There is no consistent evidence supporting a role of IgE-mediated food allergies in IBS.

However, there is an association between the two conditions among people who have IBS alongside atopy. People with atopy tend to 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 allergies, such as 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 is often focused on a different class of antibodies—IgG antibodies. The accuracy and relevance of tests that measure IgG in your blood is not clear, which means that testing for these antibodies may not be helpful for you.

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 an association between some of the foods that you eat and your IBS symptoms. You could have a food intolerance.

A food intolerance means that your body has a reaction to certain foods, but the reaction is not an IgE-mediated allergic reaction.

Several foods have been identified in research studies as potential contributors to unwanted digestive symptoms in a subset of people who have IBS:

  • Milk products due to an intolerance to lactose
  • Foods containing fructose
  • Wheat products

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.

Estimates about the impact of eliminating these foods vary 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 know whether 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 in a ​food diary.

You would do this by eliminating a type of food for a period of time to observe the effect on your symptoms. If you experience an improvement in your symptoms, you may have identified a sensitivity.

It is essential to re-introduce the food to confirm 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 healthy foods from your diet that are not really triggering your symptoms, as that could put you at risk for nutritional deficiencies .

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