Food Allergies vs. Intolerances: What's the Difference?

Photo Credit: OMED Health

Lactose intolerance affects approximately 68% of the world's population; chances are you know someone who has it. What most people don't realize is that it's not a food allergy at all. The difference between food allergies and food intolerances is significant, and people should know the difference to maintain public safety, especially in places like restaurants.

First off, allergies are caused by the body recognizing certain proteins in food as threats. It then releases antibodies called Immunoglobulin E, or IgE for short, to combat these (harmless) proteins. IgE triggers mast cells, scattered throughout the body, to release inflammatory chemicals such as histamine, which cause the symptoms of an allergic reaction.

Fun Fact: Heat can have strange effects on allergens. The reason many people with certain allergies (like dairy or eggs) can tolerate their allergens if cooked is that the cooking process (heat) can denature the proteins, making them less recognizable to the immune system and therefore not an elicitor of a reaction. That said, this is not true for all allergens; for example, roasting peanuts can actually increase their allergenicity.

Food intolerances, on the other hand, are not related to the immune system but instead a digestive problem. A food intolerance occurs when the body is not able to break down a food. This is usually due to natural enzyme deficiencies that limit what can be digested. The indigestible material irritates the gut and causes discomfort.

The difference lies in the reactions and the severity: allergic reactions can take the shape of anything from mild hives and itching to full-blown life-threatening anaphylaxis. A couple of severe symptoms of anaphylaxis are throat swelling, severe abdominal pain, and a rapid drop in blood pressure. Even a minuscule amount of allergen contact (including airborne exposure in rare cases) can elicit an extreme reaction. Allergic reactions usually begin to appear within 2 hours of contact.

Food intolerance reactions are generally milder than allergic reactions. Their severity is commonly dependent on the amount of food ingested, unlike allergic reactions. A food intolerance can lead to an upset stomach, indigestion, bloating, and gas. Also unlike allergies,

symptoms of food intolerances can show up many hours or even days after ingestion. People with intolerances can usually still have those foods in limited amounts.

My family and I went to Cancun, Mexico, for a vacation a couple of years back. We were having breakfast, and my brother, who had a severe dairy allergy at the time, told the server about his allergy and asked for no milk. This was misinterpreted as lactose intolerance rather than a dairy allergy, and they offered lactose-free milk. Luckily, because he was aware, he didn’t drink it, and my mom was on it to tell the staff.

Knowing the difference between food allergies and intolerances is essential for safety, as allergies can trigger life-threatening anaphylaxis requiring immediate medical care, whereas intolerances cause non-lethal, but still uncomfortable, digestive issues. Distinguishing them ensures proper management, such as strict avoidance of allergens, and helps prevent over-the-top dietary restrictions for intolerances.