Food Allergy or Intolerance: What’s the Difference?

Food Allergy or Intolerance: What’s the Difference?

You’ve started to experience stomach pain and discomfort every time you eat one of your favorite foods. One day you stop and ask yourself, “Wait, is this a food allergy? What about a food intolerance? Or could it be something else altogether?”

Before you chalk it up to an allergic reaction and start taking foods out of your diet, it’s important to know the differences between a food allergy and a food intolerance—and how you can work with medical professionals to better understand both. Knowing the differences between these two health conditions and understanding your own susceptibility to potential allergens and irritants can help you make better food choices and feel more comfortable during and after your meals.

So, what’s the difference between a food allergy and a food intolerance?

Food Allergies affect the Immune System.

Food allergies are characterized by an immune response to protein in food. The body’s immune system goes into defense mode and begins fighting off the offending proteins it considers harmful.

Foods that are known to cause allergic reactions are called allergens. The major allergens in the U.S. are milk, eggs, peanuts, tree nuts, soy, wheat, fish and shellfish and are commonly referred to as “The Big Eight.”

Some individuals who consume these allergens can have an adverse (allergic) reaction to the foods. Typical symptoms of allergic reactions include skin irritations, nausea, vomiting, diarrhea and life-threatening anaphylaxis: the most severe form of allergic reaction.

Many of these symptoms may leave you feeling sick but experiencing them is not enough to diagnose a food allergy. In fact, food allergies can only be diagnosed by a medical doctor who is a board-certified allergist. Allergists use a number of techniques to diagnose a true food allergy. These diagnostics can include a medical history, an oral food challenge, a skin-prick test, and a blood test.

Food Intolerances affect the digestive system.

Food intolerances take place solely in the body’s digestive system. They do not involve the immune system. An intolerance to food can occur when our bodies lack specific proteins needed to break down certain foods. They can also occur when a food component causes irritation within the digestive system. The most commonly known food intolerance is lactose intolerance. This condition is caused by a lack of lactase, a protein needed to digest the milk sugar lactose.

Symptoms of food intolerance can include headaches, nausea, stomach pain, diarrhea and vomiting. While these symptoms might resemble those of a food allergy, a major difference is that food intolerances do not lead to anaphylaxis. While discomforting, it’s rare that food intolerances become life-threatening.

Food intolerance diagnoses must be diagnosed by a medical professional, physician or allergist. If a physician thinks you have an intolerance, they may suggest additional medical tests (e.g., a stool acidity test) to confirm a food intolerance.

Lactose Intolerance Explained

“Lactose intolerance and milk allergies are not the same. Lactose intolerance affects the gastrointestinal system. It does not involve the immune system and is not life threatening. A milk allergy does involve the immune system and can be life-threatening.” –Dr. S. Shahzad Mustafa, MD; Rochester School of Medicine

What are you experiencing?

Food allergies can be life-threatening and involve the immune system. Food intolerances cause a great deal of discomfort by affecting the digestive system, but they are not fatal.

To help find out if you have either or both conditions, begin by keeping a food journal. This tool can be used to track your meals and the symptoms you experience after eating. As soon as possible, visit your doctor—who can provide an official diagnosis or a referral to an allergist. A physician can help you pinpoint what’s causing your discomfort and advise you on diet and other treatments. Finding the exact cause will allow you to continue enjoying as many foods as possible.

This blog post was written by Casey Terrell, MPH, RD.