21 September 2017

A new way to diagnose food allergies

Researchers are suggesting a new 'food challenge' to pinpoint food allergies. This method is safe and won't cause any dangerous reactions.

Diagnosing a food allergy isn't always simple, but the best way to do it is through an oral food challenge, according to a new study.

"It's important to have an accurate diagnosis of food allergy so an allergist can make a clear recommendation as to what foods you need to keep out of your diet," said study senior author and allergist Dr Carla Davis.

"And if no allergy exists, that clears the way to reintroduce foods you may have thought were off-limits," said Davis, an associate professor of paediatrics at Baylor College of Medicine in Houston.

What is an oral food challenge?

During an oral food challenge, patients are asked to eat a very small amount of a suspected allergen while under the close supervision of a specially trained doctor, called an allergist. This doctor will evaluate the person for signs of an allergic reaction.

Researchers who analysed more than 6 300 oral food challenges found these tests were safe and caused very few people to have a serious allergic reaction. Most of these tests involved children and teens younger than 18.

Of these cases, 14% resulted in a mild to moderate reaction that involved just one part of the body, such as a skin rash. The researchers noted that 2% resulted in very severe reactions that affected multiple body systems (anaphylaxis).

The results were published in the journal Annals of Allergy, Asthma and Immunology.

Safer than prior studies

"Oral food challenges are a very important tool for anyone who wants to know if they have a food allergy," said study lead author Dr Kwei Akuete, an allergist at Texas Children's Hospital in Houston. "Our study showed [oral food challenges] are safer than prior studies estimated, and should be routinely used to help determine if a food allergy exists."

Making a food allergy diagnosis is very important for people's health and quality of life, the study authors said.

"Food challenges improve the quality of life for people with food allergies, even if they are positive," Davis said in a journal news release. Delaying a diagnosis can lead to increased health costs to the patient and raise the risk for nutrition problems, especially for children, she added.

Understanding food allergies

According to Health24, the most common allergies in South Africa are eggs, peanuts, cow’s milk, tree nuts like hazelnuts and soya. Symptoms can vary from immediate reactions to reactions that can even occur days later. Symptoms also vary:

1. Skin rashes and itching

Food allergies can cause swelling, hives, red itchy eyes, an itchy mouth, sneezing or coughing. 

hand with hives

2. Digestive symptoms

Some food allergies can cause digestive symptoms such as colicky stomach cramps, diarrhoea, severe reflux, vomiting or nausea. 

woman with stomach cramps

3. Anaphylactic shock

An allergic reaction in its worst form is anaphylaxis, which can lead to cardiovascular symptoms, drop in blood pressure, coma and even death.medical ER

Image credits: iStock 


Ask the Expert

Allergy expert

Dr Morris is the Principal Allergist at the Cape Town and Johannesburg Allergy Clinics with postgraduate diplomas in Allergology, Dermatology, Paediatrics and Family Medicine dealing with both adult and childhood allergies.

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