You have probably heard both the term “food allergy” and “food intolerance” before and some people will use them as interchangeable terms.  However, even though some of the signs and symptoms can be similar between the two, these are entirely different conditions. Read on to find out more about how a food allergy is different than a food intolerance.

An Overview of Food Allergies

The basis of a food allergy lies in the immune system and is an immune system reaction.  When you eat a food that you are allergic to for the first time, your body makes antibodies. When you eat that food again, the antibodies recognize this as a foreign or harmful substances and mount an attack against it, releasing chemicals called histamines that are responsible for some of the uncomfortable signs and symptoms of a reaction, including tingling in the mouth, swelling of tongue or lips, runny nose, watery eyes and gastric symptoms like nausea, vomiting and cramping.   The effect on the skin and respiratory system is believed to indicate a food allergy instead of a food tolerance.

A food allergy can also trigger a severe, life-threatening reaction called anaphylaxis. When this happens, swelling in the throat can cut off the airway and lead to a drop in blood pressure, shock, cyanosis (turning blue), fainting and loss of consciousness. This is considered to be an emergency and must be treated with an injection of epinephrine (via an Epi-Pen) to bring down swelling and open airways and a trip to the emergency room for more advanced treatment.

Common foods that people are allergic to include shellfish, peanuts and soy.

The best way to treat a food allergy is to avoid the food altogether: even small amounts of a food that you are allergic to can trigger a reaction. If symptoms are mild, however, they can often be treated with an over-the-counter antihistamine to manage them.

An Overview of Food Intolerance

The most important difference between a food allergy and food intolerance is that it is not an immune system reaction and is not considered to be life-threatening. There are in fact, many possible causes of food intolerance and some conditions which closely mimic it:

  • Lack certain enzymes. One common reason for a food intolerance is a lack of certain enzymes that are needed to break it down properly in the body. A good example of this is lactose intolerance, which is caused by a deficiency of the enzyme lactase, a chemical that is needed to digest lactose (a milk sugar) in the body. People with lactose intolerance can get hives, nausea and vomiting after eating a food they are intolerant of.
  • Other common causes of food intolerance or conditions that mimic it include irritable bowel syndrome, food poisoning (due to the bacterial toxins), response to stress and diagnoses like Celiac disease.

Some of the signs and symptoms of food intolerance may mimic the signs and symptoms of a food allergy, including nausea and vomiting and diarrhea.  Other symptoms are more particular to food intolerance: reactions to food tend to come on more slowly and can also include gas/bloating, headaches and irritability.  These symptoms tend to come on more gradually than do the symptoms of an allergic reaction and often only occur if a certain food is eaten too often or in too great a quantity.

Unlike those with food allergies, people with food intolerances can sometimes eat small amounts of the food they are sensitive to without triggering a reaction.

Common triggers of food intolerance include caffeine, toxins found in undercooked beans and the histamine and salicylates which naturally occur in certain foods.

There are also treatments like lactase supplements which someone with lactose intolerance can take before eating or drinking a milk product that can keep them from these uncomfortable symptoms.  Sometimes it is necessary to first treat the underlying cause of a food intolerance – such as irritable bowel syndrome – in order to improve this condition.

In short, then, while there are some symptoms are common to both a food allergy and food intolerance, there are some big differences, too, the most important being that a food allergy, unlike an intolerance, is an immune system reaction mediated by IgE in the system which will release histamines in the presence of a certain food.  Also, food allergies have the potential to be dangerous or life-threatening, where food intolerances do not.

If you are worried that you may have either of these conditions, it is a good idea to make an appointment with your doctor to discuss the problem and come up with a game plan which will help to relieve your signs symptoms and get you back on track.