Certain food options, hidden ingredients trigger allergies in some persons. This copy explains in detail the tests and treatment of food allergies. While some people may already be aware of what foods they are allergic to, others may need to consult an allergist as a first step towards diagnosis and management for food allergies.
“It is important to read the labels of the products you are consuming in case you are aware of your allergies,” says Dr Ajay Agarwal, director and head of department, internal medicine, Fortis Hospital, Noida.
For those who aren’t aware of the foods they are allergic to, the allergist will first examine the person and then decide on the food allergy test to be conducted and the method of management to be adopted.
For an accurate diagnosis, the doctor must be very attentive to the food consumption history. “The pattern of these reactions must be evaluated clinically,” says Dr Sujatha Ramesh, an allergist from Manipal Hospitals, Yeshwantpur, Bengaluru. “It’s important to pinpoint the nature and cause of the reaction and distinguish between food intolerance and true allergy. Allergy is an immunological reaction.”
Dr Agarwal recommends maintaining a food diary to track reactions to food. “Note when you have reactions from food and avoid those foods next time,” he says.
With the detailed medical history and food diary, allergists will be able to determine which test to take to diagnose the suspected food allergy.
Skin prick test (SPT) for food allergies
“The most commonly used test for food allergies diagnosis is the simple skin prick test which gives you a result within 10 to 15 minutes,” says Dr AB Singh, secretary, Indian College of Allergy, Asthma and Clinical Immunology and former scientist emeritus, Institute of Genomics and Integrative Biology, Delhi.
In this type of test, conducted in a controlled environment (an allergist’s clinic, for instance), the skin of the person with a suspected food allergy is pricked with a needle that contains a drop of the suspected allergen. Do keep in mind, however, that about 50 to 60 per cent of all skin prick tests turn up ‘false positive’ results.
Allergen-specific immunoglobulin E (IgE) test
Based on the person’s medical history, blood tests are conducted to look for specific antibodies against the suspected allergen via immunoglobulin E (IgE) tests. If the person has an egg allergy, for instance, then the test results will show elevated levels of egg-specific IgE,” says Dr Ramesh.
Oral food challenge (OFC) test
Dr Singh says another reliable type of test is the oral food challenge (OFC) test, where the person who is suspected of having food allergies is asked to take small amounts of, say, peanut or tree nut (suspected allergy-causing food) and find out at what point they begin to show symptoms of an allergic reaction. This test has to be done in a hospital environment so that any allergic reactions can be treated quickly.
The severity of an allergy cannot be detected on the basis of SPT or specific IgE and can only be detected by an OFC test or component resolved diagnosis (CRD).
In OFC for an egg allergy test, for instance, usually baked egg is given. CRD is a diagnostic and prognostic test for egg allergy to detect specific IgE against individual allergen molecules.
Food allergies: Treatment
According to Dr Ramesh, one has to determine the severity of the infection to be prepared to handle the allergic reaction. “If the child had a history of anaphylaxis, then the risk of re-exposure is possible, and the child must be taken to a hospital,” she says.
Dr Ramesh says that such critical cases are treated with adrenaline, epinephrine autoinjectors (also known as EpiPen, it is a life-saving auto-injector medical device filled with a specific dose of adrenaline), antihistamines and oral steroids.
Mild reactions are treated with antihistamines. When it comes to children, she says, caregivers or parents must keep a record of everything the children have eaten.
Dr PC Kathuria, chest physician and allergy immunotherapy, critical care specialist, National Allergy Centre, New Delhi, suggests that those with a history of egg allergy and anaphylaxis reactions must carry an epinephrine auto-injector while eating out. They should also make sure that the EpiPen is not past the expiry date.