Ask the Doctor: My daughter has been diagnosed with IBS but may have a food intolerance. Should we have them tested?

Question: My daughter has suffered terribly with her stomach and has been going to her GP for a year with no joy. She has been sent for tests and her GP says there is not much more she can do and that my daughter has IBS. I wonder if there are alternative ways of looking at it. A friend told me about a hair sample food intolerance test that did wonders for her daughter. It’s very expensive so I wanted to ask if you have any thoughts on that?

Answer: I think you would be wasting your money paying for expensive hair tests to uncover supposed food intolerances. These types of tests, when subjected to proper scientific evaluation, show a lack of reproducibility and no association with a disease. There is no role for hair analysis, isolated IgG testing, kinesiology, Vega testing or enzyme-potentiated desensitization, acupuncture, or naturopathy for the diagnosis or treatment of food allergies or intolerance

Also, abdominal pain in children is notoriously non-specific and it is very reassuring that your GP has ruled out all major gastrointestinal (GI) conditions such as celiac disease or inflammatory bowel disease. Allergy tests are of no value in clarifying abdominal symptoms in children.

I suggest that you look at your child’s social, emotional, and developmental milestones. Does she have trouble studying at school? Has any of her teachers ever raised concerns about possible dyslexia, dyscalculia, dyspraxia, or noticed her being sad or crying in class? Does she have a good network of friendly, supportive friends? Does she happily participate in extracurricular activities?

Food intolerances generally cause gastrointestinal symptoms such as bloating, gas, abdominal pain, diarrhea, but other symptoms such as rash/itching or headaches can also occur. The amount of food eaten is directly related to the severity of symptoms, and eating causes similar symptoms each time. There is currently no validated test to confirm delayed or non-IgE mediated food allergy or intolerance (cell-mediated/type IV hypersensitivity).

In general, children with a true food allergy (much more severe than a food intolerance) have other atopic diseases, particularly eczema, occasionally asthma and allergic rhinitis. The exact incidence is unknown but is believed to be very similar to that in the UK – 3-6 per cent of pre-school children and 1-2 per cent of older children and adults

The most common food allergens in infancy and childhood are cow’s milk, eggs, peanuts and tree nuts, fish and shellfish account for more than 90 percent of cases. Most children will outgrow a milk or egg allergy. Most children will not outgrow a peanut, tree nut, seed, fish, or shellfish allergy. Wheat allergy is extremely rare and presents in early infancy with severe urticarial reactions and is therefore easy to recognize. Currently, the best way to help diagnose a food allergy is through skin prick and blood tests to assess the production of IgE antibodies to the specific allergen.

Specific IgE allergy tests have a relatively low positive predictive value (about 50 percent) and should only be tested for two or three suspect foods. In contrast, negative IgE test results are highly specific and have a 95 percent negative predictive value for milk, egg, and peanut. These tests have no value in evaluating abdominal symptoms such as constipation, diarrhea, bloating, or abdominal pain. It is important to consider food allergy in children with food refusal, severe aversive eating behaviors, problems progressing the weaning diet, failure to reach predicted growth milestones, and one or more gastrointestinal symptoms, especially if they also have difficult-to-control eczema.

The best way to address your concerns about your child’s food intolerance is with the expert guidance of a registered dietitian who can oversee the restriction of the exclusion and reintroduction of certain foods. This should be timed (four to six weeks) and exclude no more than four foods.

dr Jennifer Grant is a GP at Beacon HealthCheck