What is the difference between food allergy & food intolerance?

THERE IS AN INCREASING TREND TO EAT gluten-free, to avoid dairy and to cut out sugar. People are doing this whether they are allergic, intolerant or neither. Is what you eat just a (healthy) preference or is there something more going on? In this post I will explain the difference between a food allergy and food intolerance.

FIRST, LET’S HAVE A LOOK at this diagram. It pretty much explains what is going on.

What is food hypersensitivity?

Food hypersensitivity is having an adverse reaction to any food. Hypersensitivity can be divided into two groups:

  1. food allergy and
  2. food intolerance.

These are not the same thing. Read on for more information.

What is food allergy?

Food allergy is when eating certain foods causes an allergic reaction. It means that a food activates the immune system, causing a reaction similar to when the immune system reacts to any bacteria or virus: inflammation.

The pillars of inflammation are something each medical student can name if you wake them up in the middle of the night (but don’t, sleep is important). These pillars are redness, pain, swelling, itchiness, and eventually loss of function.

This is what a person who is allergic to certain foods experiences when their immune system is exposed to that food (or to other molecules that look like molecules in this food).

The reaction can be mild, or more severe, and can even lead to potentially lethal anaphylactic shock, in which an Epi pen needs to be administered straight away to prevent death.

What is happening in the body in the case of eating a food you are allergic to, is that immune cells are basically triggered to go crazy bonkers, completely forgetting everything else other than their need to react to this “bad guy” food. Immune system becomes activated and causes inflammation at the place where there’s the food (for example, the lips or throat).

FOOD ALLERGY EXAMPLES: peanuts, shellfish, soy, eggs, wheat.

What is food intolerance?

Food intolerance is a completely different issue than food allergy. Food intolerance is brought about when our body has difficulty digesting certain foods. For example, lactose intolerance is caused by missing an enzyme that breaks down lactose (this enzyme is called lactase (notice it ends with the phrase -ase, just as most enzymes)).

food allergy versus food intolerance

People who cannot break down lactose end up experiencing side-effects when consuming milk products, such as bloating or diarrhea. This is in no way pleasant, but it is much different than the activation of the immune system seen in food allergies.

Aversion to certain foods is also a form of food intolerance. Disliking the flavor and becoming nauseated by a smell of certain foods, are other examples food intolerance.

FOOD INTOLERANCE EXAMPLES: cow’s milk, goat’s milk, cheese, gluten (gastrointestinal symptoms such as bloating without inflammation of the bowels), certain vegetable, certain fruit.


Are you allergic or intolerant to certain foods?

Maybe you started reading this post thinking that you are allergic to certain foods and now realise that what you are experiencing is actually food intolerance? Or perhaps even the other way around?

I hope this post helps in distinguishing between these very different but very commonly used terms.

Images from allergycentre.com.my , healthyeats.mobi.

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