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25 June 2024

Food Intolerance: testing and common triggers

Dr. Vito Annese, Consultant Gastroenterologist

By Staff

Food is an integral component of people’s culture and lifestyle, but, it is also important to be aware of which foods you are sensitive to as this can impact your health in surprising ways.

Food intolerances are often tricky to diagnose, as the symptoms and reactions can be hard to identify right off the bat. Though intolerances can cause considerable discomfort, the reactions are never life-threatening, in contrast to that provoked by food allergy.

It is also important for people to understand that there is a significant difference between food allergies and food intolerances as these terms are often used interchangeably.

A true food allergy causes an immune system reaction that affects numerous organs in the body with the production in most cases of specific antibodies (Immunoglobulin E). It may present up to 5% of individuals and more frequently in children, especially for egg, milk and shellfish.

Food intolerances are much more frequent (up to 20% of population), raise a different pathway, but still invoke similar symptoms and reactions such as irritability of the bowels, upset stomach, and sometimes rashes and itching.

Food intolerance can be hard to pinpoint because the onset of symptoms is usually slower, can last for several hours or days, and can even increase or decrease in strength depending on the amount of food one’s ingested.

The most common food intolerances include histamine, with high contents found in chocolate, nuts, matured cheese, and ready meals, and lactose, found in milk and dairy products. Sulphites and fructose are other common food intolerance triggers, found in dried fruit, canned goods, wine, honey, and fruit juices.

Addressing food intolerance may prove to be increasingly beneficial for a patient’s health and testing for certain foods and then eliminating or reducing them can help patients seek relief from painful symptoms.

Dr. Vito Annese, Consultant Gastroenterologist at Valiant Clinic, the leading premium outpatient multi-specialty clinic in the UAE and the region, offers some of the most effective types of intolerance/allergy tests available:

1. Hydrogen Breath Test for lactose intolerance: The hydrogen breath test is used to identify, lactose intolerance, the sugar present in milk and dairy. A breath sample will be collected and tested for the presence of hydrogen.

To obtain the sample, you will be asked to blow within a tube connected to a portable equipment. You will then be given a pleasant-tasting solution to drink that contains lactose. Breath samples are collected every 15 to 20 minutes for up to three hours, as the solution is digested, to see if there is any increase in hydrogen in the breath. Increased hydrogen breath levels mean that there are problems with digestion of lactose.

2. Hydrogen Breath Test for fructose intolerance: Similar to the above, this test identifies fructose intolerance by breath collections.

The first collection is before 25 grams fructose is given to you.  Breath samples are then collected every 15 to 20 minutes for up to three hours, as the solution is digested, to see if there is any increase in hydrogen in the breath. Increased hydrogen breath levels mean that there are problems with digestion of fructose.

3. Hydrogen Breath Test with glucose: This test is performed to disclose possible bacterial contamination (or overgrowth) in the small bowel.

Breath samples are collected at baseline and then every 15-20 minutes for up to three hours after drinking the solution with glucose. In this case is not evaluated a specific intolerance, but a condition with similar symptoms such as bloating, abdominal discomfort and eventually diarrhea due to increased presence of bacteria within the small bowel.  

4. Food Diary for FODMAP intolerance: A food and symptom diary can help you investigate whether specific foods are triggering an unpleasant response in your body, such as bloating for example.

This diary can also be very helpful when discussing your symptoms with a dietitian or qualified nutritionist. They can then help you determine which specific foods you need to restrict, how to find alternatives to those foods, and how to ensure you still get a nutritionally complete diet.

5. Prick Test for food allergy: To diagnose a food allergy,  a skin prick test is performed to provoke a possible skin reaction to specific foods. Results are taken after 15 minutes. 

Positive results are indicated by a wheal; a raised white bump surrounded by a small circle of itchy red skin. In general, a large wheal is more likely to indicate a true food allergy, but size is not always an accurate predictor.

If no wheal appears, it is unlikely that you are allergic to the test food. When there is a skin reaction subsequently a blood sample is taken to evaluate the titer of IgE antibodies and specific subclass of food (i.e. testing specific fishes and species in the event of positive skin test to seafood or shellfish).