Food sensitivities, or food intolerances are abnormal reactions to foods, these terms are often used interchangeably. However, food sensitivities are different from food intolerances, because they involve an activation of the immune system. When we are exposed to foods, the immune system can react by releasing proteins called antibodies. Foods that cause antibodies to be released are called antigens or allergens. There are two types of antibodies that are commonly produced in response to food: IgE (immunoglobulin E) and IgG (immunoglobulin G). Food allergies and food sensitivities differ in the type of antibody produced and the speed at which the reaction occurs. A true food allergy is an immediate reaction (such as anaphylaxis) caused by the production of IgE antibodies, whereas a food sensitivity is a delayed response caused by the production of IgG antibodies. 

IgG reactions can take hours to days to develop, making it difficult to pinpoint the food cause without testing. What happens in an IgG reaction? In an IgG reaction, the IgG antibodies attach themselves to the antigen and create an antibody-antigen complex. Normally these complexes are removed by our macrophages (special immune cells), but if these complexes are present in large quantities and the food is still being consumed, the macrophages become overwhelmed and can’t remove all the complexes. These antigen-antibody complexes accumulate and can be deposited in body tissue. Once deposited, they may lead to inflammation, which can then contribute to a variety of health conditions. 

What Are Delayed Food Reactions?

Inflammatory reactions triggered by antibody-antigen complexes may result in:

  • Systemic reactions such as fever, fatigue, chills, sweating and feeling weak, and/or puffiness.
  • Skin reactions such as itchiness, redness, swelling, and rashes.
  • Mood and memory disturbances, or behavioural problems (such as ADHD, ADD, etc.).
  • Asthma symptoms or food-induced bronchitis.
  • Joint pain, muscle stiffness, or swelling.
  • And the most common reactions include: nausea, vomiting, diarrhea, abdominal pain, gas, and bloating. 

Conditions Associated with Food Sensitivities:

The most common conditions associated with food sensitivities include digestive disorders such as irritable bowel syndrome (IBS) and Crohn’s disease. However, migraines have also been linked to food sensitivities, along with mood disorders such as depression, anxiety, and difficulty concentrating. There is also evidence that eliminating food sensitivities can improve attention deficit disorders in children and adults. Weight gain and fluid retention are also strongly tied to food sensitivities. Antigen-antibody complexes cause inflammation, to fight inflammation the body releases a chemical called ghrelin, which also happens to be an appetite stimulant. Therefore, IgG food reactions can contribute to weight gain in 2 ways: fluid retention and an increase in appetite. 

How to Determine Your Food Sensitivities

Because food sensitivities can take hours to days to appear, testing is often the only way to determine which foods are responsible for the reaction. Food Sensitivity Testing involves a simple blood draw, the sample is sent to a specialized lab for testing, and a report is generated with the results. There are three testing options, and up to 220 foods can be tested. Results are categorized in food groups such as dairy/eggs, grains, fruits, vegetables, meats, seafood, nuts/seeds/legumes, and miscellaneous. The report demonstrates which foods are normal (no reaction), borderline, and reactive. Your practitioner will review the results with you and formulate a plan to eliminate problem foods from the diet. 

Most individuals see an improvement in their symptoms within 3 weeks of eliminating their reactive foods. According to research, the digestive system and psychological symptoms such as anxiety and depression showed the most improvement. It is important to note that symptoms may return when reactive foods are added back to the diet. 

For more information about food sensitivity testing contact us at Your Health Collective, 905.619.3737 or


Yours in health, 

Dr. Kate Klein, ND 

About the Author

Dr. Kate Klein is a licensed naturopathic doctor and clinic director at Your Health Collective, an integrative wellness clinic located in the heart of Ajax. Dr. Klein and her team offer services including, naturopathic medicine, holistic nutrition, acupuncture, osteopathy, and psychotherapy to patients of all ages. Practitioners at Your Health Collective provide a collaborative approach to patient care through a variety of natural treatments and solutions for health concerns ranging from disordered sleep, allergies, fertility, headaches, digestive concerns, and much more. We believe that health is more than just the absence of disease; health is when we function at our best through proper nutrition, exercise, a balanced lifestyle, positive emotions, thoughts and actions. For more information about Dr. Klein, naturopathic medicine, or our clinic please visit: