Known food reactions of all kinds affect at least 5-10% of the population.   I suspect that the actually number is much higher for a variety of reasons, not the least of which is the lack of clarity about the meaning of the terms to describe the different types of food reactions. 

In this blog I’d like to clear up the confusion around the meaning of different terms related to adverse food reactions.   

First of all, think of “food reaction” as a general, non-specific term to describe any undesirable, unintended reaction to the ingestion of a food.  It’s a big umbrella term that encompasses the more specific types of food reactions, like allergy, sensitivity and intolerance.  I like to use the analogy of a pie chart (pardon the pun) to describe the term food reaction.  The different types of food reactions, like allergy, sensitivity or intolerance are the slices of the pie.  Let’s describe each of these slices of the pie in more detail. 

Food allergy & Sensitivity

Of all the food reactions, only food allergy and food sensitivity directly involve the immune system.  Notice I said, directly.  An argument can be made that all food reactions, over time, will have an adverse effect on the immune system.  In fact, immune system activation that instigates whole body inflammation is one of the primary reasons to identify potential food reactions.   But not all food reactions involve the immune system directly, meaning that actual changes in specialized immune cells called antibodies can be measured. 

Food allergies and sensitivities, while different, do share the commonality of producing specific antibodies called immunoglobulins in the blood.  There are 5 classes of immunoglobulins in the body – IgE, IgA, IgG, IgM and Ig,D. 

In the case of allergy, the class of antibodies that are produced are from the IgE family.  IgE antibody production is unique to immediate hypersensitivity – the response by your body is usual swift and very notable.  You eat a strawberry and break out in hives pretty quickly, for example, oftentimes before you get to the second strawberry.  This rapid cause and effect results in a very quick learning curve for many people.  You get the connection between that food (the strawberry) and your body’s response (hive breakout, for example) and (hopefully) learn to eliminate it from your food  plan.  The intensity of the reaction can vary from food to food and from person to person.  If the reaction is mild, like a little throat clearing, there can be the temptation to ignore the possibility of a food allergy which is a mistake in my clinical opinion.  The amount of potential harm to your immune system is not proportional to the intensity of your reaction, especially over time.   

Food sensitivity will also result in a production of specialized antibodies by the immune system but these are from the IgG family.   IgG antibody production occurs as a result of delayed hypersensitivity.  You’re reacting to a food but instead of an immediate reaction, the reaction can occur up to 72 hours after you first ingested the food.  Imagine how much more confusing this can be!  You could develop a migraine this morning because of something you ate 3 days earlier.  It becomes fairly obvious how challenging it can be to identify the culprit(s).  This is when the elimination/provocation diet can be a very helpful tool to help identify possible food sensitivities.   


So, food allergies and sensitivities are two significant parts of the food reaction pie chart.  What are the others?  Intolerances to lactose and histamine are another slice of the food reaction pie.  In both of these situations, symptoms are the result of a lack of a key enzyme that is required for complete digestion of that food. 

In the case of lactose intolerance, there is a lack of production of the enzyme necessary for the complete breakdown of sugars naturally occurring in dairy products.  Taking the enzymes in pill-form or using dairy products that have the enzyme added to the product is a simple solution as long as it is done on a regular basis.  I find that dairy sensitivity is often confused with lactose intolerance.  It’s important to be as clear as possible about the distinction.  I frequently will ask clients who believe they have lactose intolerance to do a complete elimination of all dairy products for 3 weeks to determine whether they are really dealing with a dairy sensitivity.  And we sometimes find that there is a double whammy of both lactose intolerance and dairy sensitivity. 

Histamine intolerance is a much more complex issue than lactose intolerance and deserves it’s own post.  But for our purposes here, part of the problem with histamine intolerance also involves the lack of an enzyme to help break down the histamines that occur in certain foods.  Histamine is a naturally-occurring, usually short-acting, chemical produced by the immune system in response to inflammation or irritation to the immune system.  Some people have an abnormal exaggerated response to histamine or have trouble breaking the chemical down once the threat is over.  This then results in the myriad number of symptoms that can exist for the individual who has an abnormal histamine response.  Learn more about histamine intolerance at  

Food additives, preservatives and salicylates

Food additives, preservatives and salicylates are another slice of the food reaction “pie”.  Exposure to artificial food colorings, flavors and fragrances along with certain preservatives (BHT, BHA and TBHQ), artificial sweeteners and certain foods that are naturally high in salicylates – collectively called the Feingold Diet – was initially found to be helpful to treat allergies and eczema.  The elimination of these foods was found to also have a secondary benefit of calming hyperactivity in some children.  Dr. Feingold pursued this connection further in his practice and found that it was effective for ADD/ADHD and other activity/behavior issues with children.   You can learn more at

You can probably understand why there’s so much confusion out there about food reactions and how to best identify them.  Hopefully, this brief introduction to the topic will help clarify any misconceptions you might have.