What is the difference between Food Allergy, Food Intolerance and Food Sensitivity?

With an increase in awareness of food intolerances, particularly gluten and dairy,  many people are now curious about food allergies. They wonder if they have food allergies, and if they too should be avoiding certain foods to improve their health. This can be a confusing topic, so let's look a little deeper into the difference between allergic food reaction and food sensitivity or intolerance and whether you might benefit from food sensitivity testing.

Before we continue, it is helpful to have a mini biology lesson and learn a little about our IgA, IgE, and IgG immune responses. IgA, IgE and IgE refer to immunoglobulins, or “antibodies.”  These antibodies are part of our immune system, and are made in response to things we come in contact with on a daily basis. Our bodies make antibodies to foreign substances like bacteria and viral cells, but can also respond to foods, dust, animal dander, and pollen. Antibodies help the body prepare an immune system response (“fight”) against what is sees as foreign trespassers in the body.

IgA and IgG reactions are known as delayed response reactions, that include food intolerances or sensitives.

IgE responses are immediate and are considered a true food allergy. 

IgA and IgG reactions may not be evident straight away, but can take hours to days to show up in your skin or intestines, and cause a wide range of symptoms which you might not even attribute to what you eat. 

These symptoms can be related to inflammation like headaches, fatigue, brain fog, or joint pain. People with food intolerance may experience digestive upset like nausea, constipation, or diarrhoea, or skin rashes including conditions like eczema and psoriasis.

IgE Reactions
IgE immediate hypersensitivity reactions are characterised by the hives, and throat swelling that accompany anaphylactic reactions some people experience when exposed to certain foods.  Other symptoms can include wheezing, coughing, a runny nose, vomiting, swelling of the lips or tongue, tearing or redness of the eyes, or even a weak pulse and loss of consciousness.  Common foods that trigger IgE reactions are peanuts, shellfish, egg, dairy products, soy, tree nuts, wheat and fish.

IgA Reactions
IgA immunoglobulins are present in our mucus membranes and helps us fight bacteria and viruses. IgA increases in response to foods when the foods we eat cause inflammation, and in response to stress, disease, or alcohol.

IgG Reactions
An IgG reaction to food proteins suggests tolerance related to immune cell reaction. Repeated exposure, inflammation, and immune reactivity contribute to sensitivity and high IgG in response to food proteins.

Testing for Food Allergy and Sensitivities
IgE allergic reactions are tested with skin prick or patch testing as well as blood testing to know what foods and other allergens must be avoided and when an Epi-pen is an appropriate prescription.

While you can test IgG and IgA for rood reaction, this is not diagnostic of hypersensitivity or allergy. These tests may indicate a sensitivity and intolerance, as well as inflammation. While blood testing is available for food sensitivity reactions, these tests are controversial as the results are commonly not reproducible and are not as reliable as elimination diets for uncovering food sensitivity.

What About Coeliac Disease?
IgA and IgG testing can test for whether you might be gluten sensitive or intolerant. If you are not diagnosed with coeliac disease, you may be gluten sensitive (not gluten intolerant). Those who have a true allergy to gluten have coeliac disease, which is caused by an autoimmune response to proteins found in wheat and some other grains, and harms the cells of your small intestine. Testing for celiac disease is done with a blood sample looking for more specific immune reaction to gluten and gliadin and confirmed with a biopsy of the small intestine. 

Why would you consider testing for IgA and IgG food sensitivities if the tests are not 100% reliable?
• You like to see lab data with recommendations on how to improve.
• Someone you know did the testing and it helped them to feel better.
• An elimination diet may not work for you for one of these reasons:
   o They are time consuming and can take months to go through the process of eliminating and then challenging foods.
   o You have a picky/growing kid who already avoids some foods. You don’t want to restrict kilojoules or food groups entirely, or risk food aversion, or tension that can go along with an elimination diet.
   o You are busy, enjoy eating out, or don’t have time to cook, and have limited time for the shopping and meal planning that is required to follow a restricted elimination diet.

​If food intolerance or sensitivity testing seems like it might be a good fit for you, or if you prefer to try an elimination challenge diet to address your symptoms, then book in for an initial consultation with me to get started and work out the best solution for you.