Food allergy is caused by the body’s immune system reacting adversely to the consumption of a specific food. Symptoms occur shortly after a food is placed in a person’s mouth. Initial symptoms include oral itching, tingling, and swelling. Symptoms typically occur within seconds to minutes after the food is placed in the mouth. Symptoms may progress into facial swelling and hives. If the food is swallowed, nausea and vomiting may occur. Symptoms may worsen, resulting in faintness and a drop in blood pressure.
Food intolerance encompasses a wide variety of adverse reactions following food consumption. These reactions are often not caused by the body’s immune system. Intolerances may be classified as gastrointestinal, metabolic, chemical, or toxic. Gastrointestinal disorders include gluten intolerance (celiac disease) and colitis. Metabolic disorders include lactose intolerance and carbohydrate malabsorption. Chemical disorders include reactions from MSG and food dyes. Toxic reactions occur from eating spoiled foods.
Identifying Food Allergens
People often have a strong suspicion of their specific food allergy. Patients explain that every time they consume a certain food, the same symptoms occur. Symptoms occur quickly after exposure, and they resolve by the next day. Common food allergens in adults include:
- tree nuts
- finned fish
- raw fruits
Children may additionally be allergic to:
- cow’s milk
- hen’s eggs
These allergies can be quickly identified by allergy testing.
Diagnosing Food Intolerance
Food intolerance can be difficult to diagnose. Allergy testing does not identify food intolerance. Because of the wide spectrum of food intolerances, a careful history must be taken in order to identify a specific diagnosis. Elimination diets are sometimes needed to identify the specific food trigger. Consultation with a gastrointestinal specialist can help aid in the diagnosis of gluten intolerance and colitis. The patient’s story often guides the clinician’s path in establishing the diagnosis.