What are the Differences Between Food Allergies vs. Intolerances?

What are the Differences Between Food Allergies vs. Intolerances?

What are the Differences Between Food Allergies vs. Intolerances?


I am going to share with you about two ladies, one named Jo and the other named Flo.  Jo has always been relatively healthy and doesn’t remember suffering from allergies when she was growing up.  Now, in her 40’s, she is noticing that she seems to be having asthma-like symptoms whenever she eats dairy and she gets an itchy rash after she eats anything with tomatoes.  Her doctor suggests that she gets her allergies tested and the results confirm that she is indeed allergic to dairy, tomatoes, mold and spring grasses.

Flo, on the other hand, doesn’t feel like she reacts immediately to anything, but she suspects that food could be behind the migraines and IBS symptoms she has been experiencing.  She has weird, itchy dry spots that come and go and the fatigue she experiences after she eats, makes her feel drugged.  Flo’s doctor also suggests getting her allergies tested but they all come back negative.  This is frustrating for her because she KNOWS the way she is feeling has something to do with food, but what?  She goes to a doctor that a friend tells her about, who does a different kind of food reaction testing, called IgG or food intolerance testing.  The results of that test showed that she does, indeed, react to several food and especially to the ones she suspected.  The doctor told her that she would need to take those foods out of her diet for the symptoms to improve and when she did as he said, she felt much, much better!!!


There is a lot of confusion about the difference between food allergies and food intolerances.  There is also a misunderstanding that if the reaction isn’t an actual allergy, it isn’t a big deal.  Let’s shed some light on these two immune system freak outs.

Food allergies occur when a part of the immune system called Immunoglobulin E (IgE) mistakenly targets a food protein, thinking it is an invader, and attacks it.  It attaches to another immune cell called mast cells, which release histamine and other chemicals, which is what causes the allergic reaction.

Symptoms of this kind of reaction include hives, itchy mouth, nausea, vomiting, diarrhea, runny nose, asthma and itchy eyes.  Severe allergic reactions can include swelling of the lips, tongue and throat, shortness of breath, wheezing, turning blue, dropping blood pressure, weak pulse, loss of consciousness and an impending sense of doom.  Allergic reactions usually occur not long after the food has been ingested.  Anaphylaxis is also possible with IgE food reactions.

Food intolerances are another immune reaction all together. This gets a little complicated, so stick with me.   These are usually an Immunoglobulin G (IgG) reaction, wherein IgG antibodies attach themselves to the protein in foods and then create something called antibody-antigen complex.  These complexes are usually removed by special cells called macrophages.  However, if there are a large number of complexes and the offending foods are still eaten, the macrophages can’t remove them quickly enough.  The number of complexes increase, deposit themselves in the tissue and then release inflammation causing chemicals.

IgG immune reactions usually occur hours to days after eating the offending food.  They are not life threatening, but they can make life pretty miserable.  Reactions can include headaches, nausea, bloating, diarrhea, fatigue, dark circles under the eyes, eczema.  There has even been research linking IgG intolerances to autism, IBS, ADHD, cystic fibrosis, rheumatoid arthritis and epilepsy.

There is some controversy about the validity of IgG intolerance testing and you will be hard pressed to find a mainstream allergist who will give credence to this kind of testing.  We have found, though, through our many complicated medical issues, mainstream medicine doesn’t always stay on top of the latest in health research, especially if there is no medicine to be prescribed.  Everyone in our family has had this kind of testing, through a functional medicine practitioner and we have found it to be accurate and invaluable.  For my youngest daughter, and in my opinion, anyone who has “allergy” or auto-immune looking symptoms, it has been a game changer.


Here is the final thought I will leave you with:  It is very important to determine food allergies first, since they can be life threatening.  They usually don’t go away (but sometimes they can if they are allergies with lower reactivity) and can be treated with medicines like antihistamines and steroids.  Food intolerances do not go away and usually get worse as the offending food is eaten over time.  They aren’t known to be life-threatening but they are very probably behind chronic issues like migraines, digestive issues, fatigue, joint aches, inability to lose weight, rashes, behavioral issues, inability to concentrate and insomnia.  Antihistamines do not prevent or lessen these reactions and the only medicine that can help are ones that help symptoms like ibuprofen for pain and melatonin to help with sleep.


Both allergies and intolerances are not fun to live with but knowing the monster you are fighting lessens the battle.




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