Food Allergy vs. Food Sensitivity vs. Food Intolerance – Potential Root Causes of Illness

What is the difference between a food allergy, sensitivity, and intolerance?


This is a very common question that can lead to some confusion. So let’s try and understand it! The main difference between a food allergy, food sensitivity, and food intolerance is the way your body responds. Both food allergies and sensitivities result in responses by the immune system. However, food intolerances are caused by responses in the gastrointestinal tract – part of your digestive system. Ultimately, food sensitivities or intolerances are more common than food allergies, however, food allergies tend to be more immediate reactions and can be fatal.



With food allergies, the immune system elicits an allergic reaction in response to a certain food. This is because your immune system mistakenly identifies some protein in the food you eat as an invader and tries to fight it off by creating immunoglobulin E (IgE) antibodies. IgE antibodies can create powerful inflammatory responses with varying symptoms which can be life-threatening. It is important to avoid all food allergies and keep an EpiPen on hand at all times.


Food Allergy Symptoms:

  • Hives or rashes on skin

  • Itching

  • Swelling

  • Nausea or dizziness

  • Shortness of breath

  • Anaphylaxis – a severe life-threatening allergic reaction

Most Common Food Allergies:

Milk, eggs, fish, shellfish, peanuts, tree nuts, wheat, and soybeans


How to Test for a Food Allergy?

The most common way to test for a food allergy is a skin/patch test where they expose your skin to particular foods and observe any irritation or visible responses. Other tests including blood tests which identify IgE antibodies can also be conducted.


With food sensitivities, certain foods trigger your immune system to create internal inflammation. When you eat a particular food, it triggers a delayed immune response which can cause inflammation anywhere in the body and can take up to 96 hours which is why it is difficult to pinpoint a food sensitivity. For example, if you eat eggs on Monday and your joints are achy on Thursday it is unlikely that you are going to connect the two without food sensitivity testing or an eliminator diet. The true cause of these immune responses and sensitivities is typically an underlying digestive condition called a “leaky gut”, where there is increased intestinal permeability, or gaps in the intestinal lining. Continuing to eat foods that your body has a sensitivity to can increase these gaps even more and cause worsening of the leaky gut. To learn more about leaky guts visit our previous blog here.


Food Sensitivity Symptoms:

  • Muscle or joint pain

  • Chronic congestion

  • Chronic skin rashes

  • Bloating

  • Constipation

  • Diarrhea

  • Migraine headaches

Most Common Food Sensitivities aka “the Sinister 7”:

Gluten, dairy, eggs, nuts, soy, corn and sugar


How to Test for a Food Sensitivity?

An elimination diet is one method of identifying food sensitivities. This involves removing and slowly reintroducing each one individually while observing symptoms to identify foods that trigger responses in your body. For more details on the elimination diet, read our previous blog here. Another commonly used method is a food sensitivity blood test to identify IgG antibodies which will be elevated in the presence of food sensitivities. GLIM partners with KBMO Diagnostics to offer a state-of-the-art test that looks at 176 food items.


With food intolerances, there is an abnormal response of your intestines in digesting certain foods. This is because your body has difficulty digesting the particular foods properly which may be due to the lack of digestive enzymes needed to break down the food or sensitivity to food additives, chemicals, or contaminants.


Food Intolerance Symptoms:

  • Gas and bloating

  • Diarrhea

  • Constipation

  • Cramping

  • Stomach pain

  • Acid reflux

  • Nausea

Most Common Food Intolerances:

Gluten, lactose, salicylates, caffeine, food colorings and preservatives


How to Test for a Food Intolerance?

Similar to food sensitivities, the most common way to test for food intolerances is by eliminating the food, tracking symptoms, and reintroducing it through the elimination diet. However, for some intolerances such as lactose intolerance breath tests or other tests may be available.



Ultimately, leaky gut from food intolerances or food sensitivities can lead to trouble absorbing nutrients and increase risk of autoimmune diseases and cancer, meaning they might be your root cause of illnesses. To learn more about root causes specific to autoimmune thyroid disease, check out the book Hashimoto’s Thyroiditis: Lifestyle Interventions for Finding and Treating the Root Cause by Izabella Wentz.


Do you experience reactions to food like gas and bloating, diarrhea, constipation, acid reflux, or others listed above and need help identifying those foods or making changes to your diet? Do you have an autoimmune condition and wonder if food might be part of a root cause? Schedule an appointment with our certified functional medicine practitioner at GLIM today to receive the help you need!


#foodallergies #foodsensitivies #foodintolerance #leakygut #labwork #immunity #foodhealth

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