Food allergy? Food intolerance? Something else? A closer look

The holidays are filled with fun, family, friends and lots of food. With a variety of foods comes a variety of symptoms that people experience.

At the holiday dinner, Maria ate a bite of the pumpkin-shrimp bruschetta and within 10 minutes developed swollen lips and began vomiting. At the same meal, Linda devoured the creamed corn and later that evening experienced bloating and diarrhea. Paula savored the cranberry-cherry sauce and immediately felt the roof of her mouth begin to itch. All three women went to see a doctor because they thought they had a food allergy.

It’s easy to confuse food allergy, food intolerance and oral allergy syndrome, but the three entities are vastly different. It is important to make the distinction because food allergies are potentially life-threatening. While allergies tend to run in families, it is impossible to predict whether a child will inherit a parent’s food allergy or whether siblings will have a similar condition.

A food allergy, or hypersensitivity, is triggered by your immune system and is an abnormal response to a food. A food allergy reaction occurs when your immune system overreacts to a food or to a substance in a food, identifying it as a danger and triggering a protective response. While many Americans believe they have a food allergy, true food allergies are quite rare. They occur in about 4 percent of the general population, and fewer than 200 people in the United States die annually from food allergies.

This difference between the clinically proven prevalence of food allergy and the public perception of the problem is in part due to reactions called food intolerances. The immune system is not responsible for the symptoms of a food intolerance, even though symptoms can resemble those of a food allergy. Reactions to food allergies occur immediately, within two hours or less, while food intolerance reactions are delayed and can occur up to 72 hours after a food is ingested. With food allergies, a small amount — even traces — of food can trigger a reaction, and reactions occur almost every time the food is eaten. With food intolerance, reactions typically occur when a lot of the food is consumed and/or the food is eaten frequently.

The symptoms of a true food allergy can be life-threatening, causing anaphylaxis. That’s why it is very important to diagnose and distinguish food allergy from food intolerance. Food allergy symptoms can include, but are not limited to, generalized hives, tongue or throat swelling, difficulty breathing and swallowing and a drop in blood pressure. Food intolerance symptoms can be quite varied and can include gas, bloating, abdominal cramps, heartburn, headaches, behavioral or mood changes and eczema. Both food allergy and food intolerance can cause nausea, abdominal pain, diarrhea and vomiting. Ninety percent of food allergies are caused by the following: peanuts, tree nuts, fish, shellfish, milk, eggs, soy and wheat. The most common triggers for food intolerance include wheat, gluten, milk, fruits and vegetables.

Oral allergy syndrome, also known as pollen-food syndrome, is caused by cross-reacting allergens found in both pollen and raw fruits, vegetables and some tree nuts. People with oral allergy syndrome typically are allergic to birch pollen, ragweed pollen or grass pollen. Oral allergy syndrome symptoms include an itchy mouth, scratchy throat and swelling of the lips, mouth, tongue and throat. Symptoms usually are confined to these areas, though itchy ears are sometimes reported.

Maria was tested and found to have a shrimp allergy. She also has asthma, which increases the risk of food allergy. Linda has a food intolerance, specifically lactose intolerance, which can be caused by a number of factors. Paula was found to have neither, but was known to have a history of allergies to birch tree pollen, which points to OAS.

If you have symptoms after eating a particular food, an allergist can help determine and distinguish whether you have a food allergy, a food intolerance or oral allergy syndrome. It may be a good idea to keep a food diary to record what you have eaten, what symptoms occurred and when.

If you have a food allergy, complete avoidance of the food is essential, and carrying an injectable epinephrine device is vital in case of an emergency. If you have a food intolerance, it can be managed by limiting or avoiding the foods that cause symptoms, or your doctor may prescribe medication to help with symptoms. The symptoms of oral allergy syndrome can sometimes be minimized by the use of oral antihistamines, and often the offending foods can be tolerated in a cooked form.