Food Allergy Specialist

Food allergy is primarily a clinical diagnosis based on a history of reproducible symptoms with ingestion of a triggering food, and skin or blood allergy testing is used to support the clinical diagnosis. Allergy skin and blood testing can have up to 50% false positive rates without a good supporting clinical history.

Introducing foods early is thought to protect against the development of food allergy later in life. The Learning Early About Peanut (LEAP) study from 2015 found that introducing peanut regularly at 4-6 months of age reduced the risk of peanut allergy by more than 80%! The American Academy of Pediatrics has therefore changed guidelines to advise early introduction of peanut at 4 to 6 months of age.

Food allergy and food intolerance/sensitivity are different diagnoses. What is classically thought of as food allergy involves an antibody called immunoglobulin E (IgE), which is produced by immune cells to bind to specific proteins and act as a signaling/sensor mechanism for the immune cells to "see" the protein, since immune cells do not have eyes/ears to detect proteins on their own. In a food allergy reaction, when the immune cells "see" the IgE bound to a food protein, the immune cells overreact and trigger a too much activation in the immune cells throughout the body, leading to release of inflammatory agents (such as histamine) which can cause what are termed "IgE-mediated" symptoms like hives/rash, swelling, stomach pain, vomiting, wheezing/cough, runny nose/congestion, itchy/watery/red eyes, and/or drop in blood pressure leading to dizziness/fainting. A combination of two or more of the above symptoms is considered anaphylaxis (systemic allergic reaction), which can be life-threatening and is treated with intramuscular epinephrine injection.

On the other hand, food intolerance is not deadly but can be very frustrating, as the mechanism involves poor processing/absorption of specific food components (e.g. unable to break down the cow's milk sugar called lactose when you have lactose intolerance). Gut inflammation can occur when you cannot break down such food components, which can lead to stomach cramps, bloating, diarrhea, and more. Acid reflux is a form of food intolerance where you secrete too much stomach acid in response to certain foods (once again a processing issue), and this excess acid can cause damage in the stomach and feeding tube that leads to symptoms like heartburn, bloating, fullness, and stomach pain.

Food allergy reactions are unpredictable, which means they can be the same, less severe, or more severe compared to a previous reaction. Therefore, one should always be prepared for the worst case scenario, and always carry an epinephrine autoinjector in case there is a severe reaction.

IgE-mediated food allergy reactions are generally triggered by food proteins and not food oils. There is plenty of evidence and experience of patients with peanut allergy being able to consume foods cooked in commercially-produced peanut oil, which is the type of peanut oil generally used in major restaurant and fast food chains, as the industrial processing to produce the oil removes the peanut proteins. The types of food oils that one needs to be careful with are cold-pressed or hand-pressed oils that are typically made in small batches as they could still contain some food protein within the oil.