Food sensitivity test, food allergy test, bloating, gas, constipation, migraines, weight gain, leaky gut, skin, eczema, psoriasis, acne, IBS, IBD, fatigue, mood Naturopathic Doctor Naturopath | NatCan Integrative Medical & Wellness Centre Vaughan ON

Food Allergy or Food Sensitivity?

I often hear patients use these words interchangeably, but they’re not the same thing. So…I’ve written this blog post to set the record straight. FINALLY!!! haha

In a food reaction, the immune system reacts by releasing cells called antibodies. Foods that cause antibodies to be released are called antigens or allergens. Two types of antibodies commonly produced in response to foods are IgE (immunoglobulin E) and IgG (immunoglobulin G). Food allergies and food sensitivities differ by the type of antibody produced and the speed of the reaction. Food allergy is an immediate reaction caused by the production of IgE antibodies, while food sensitivity is a delayed reaction caused by the production of IgG antibodies to specific foods.

Food Allergy IgE Reactions - Immediate
IgE reactions generally occur within minutes of eating a reactive food and can, on rare occasions, be life-threatening (e.g. peanut allergies). Skin eruptions (hives, eczema), breathing and digestive problems are also common IgE reactions. After first time exposure to an allergen, the body remembers what the allergen “looks like” and keeps a supply of IgE ready for immediate release if it “sees” that allergen again. Referral to a specialist is recommended in the case of serious food allergies (i.e. difficulty breathing, anaphylaxis).

Food Sensitivity IgG Reactions - Delayed
IgG reactions take hours or days to develop, making it difficult to determine the food cause without testing. In an IgG reaction, the IgG antibodies attach themselves to the antigen and create an antibody-antigen complex. These complexes are normally removed by special cells called macrophages. However, if they are present in large numbers and the food antigen is still being consumed, the macrophages are unable to remove all the complexes. The antigen-antibody complexes accumulate and are deposited in body tissues. Once in tissue, these complexes cause inflammation, which can contribute to a variety of diseases and health conditions.

Delayed Food Reactions

Delayed food reactions are IgG antibody reactions (food sensitivities) that occur hours to days after a food is consumed. The inflammatory chemicals released with antibody-antigen complexes may have the following effects:

  • Systemic: Fever, fatigue, chills, sweating and feeling weak, puffiness.
  • Skin: Itching, redness, swelling, and rashes (including eczema, psoriasis).
  • Brain: Mood and memory disturbances and behavioural problems.
  • Lungs: Bronchitis and asthma symptoms.
  • Musculoskeletal: Joint pain, muscle stiffness and swelling.
  • Digestive tract: Nausea & vomiting, diarrhea, abdominal pain, gas, and bloating.

Conditions Associated with Food Sensitivities

Digestive disorders: Conditions like irritable bowel syndrome (IBS) and Crohn’s disease have been linked to IgG food reactions. Research has shown that elimination of IgG reactive foods can alleviate IBS symptoms.

Migraines: A 2007 research study found that 43/65 patients with migraine headaches had complete remission of headaches after one month of eliminating reactive foods. Another study in 2010 found a significant reduction in the number of headache days and migraine attacks with elimination of reactive foods.

Mood/attention deficit disorders: Deposition of antibody- antigen complexes in nervous system tissues may contribute to hyperactivity, depression, anxiety, inability to concentrate and other mood disorders. There is some evidence that eliminating IgG food antigens improves attentiveness in children.

Weight gain: Antibody-antigen complexes in tissue cause inflammation, which leads to fluid retention and weight gain. To fight inflammation, the body releases a chemical called ghrelin, which also happens to be an appetite stimulant. Thus, IgG food reactions may contribute to weight gain in two ways: fluid retention and increased appetite.

Testing for Food Sensitivities

The most accurate way to diagnose food sensitivities is through a blood test that measures levels of the IgG immunoglobulin in the body. The IgG immunoglobulin is produced for several hours or days after exposure to a sensitive food and persists for several weeks to months.

This method of testing allows us to test for IgG response to up to 200 different foods, giving an understanding of what food sensitivities are present, and the severity of the sensitivity.

Treatment of Food Sensitivities

Once you receive your results, your healthcare professional will help you formulate a plan to eliminate the problem foods from your diet, support and re-establish proper intestinal flora and immune function, heal damaged intestinal mucosa and correct any other underlying cause (i.e. maldigestion, insufficient enzymes). Most people see improvement of symptoms within a few weeks of eliminating the reactive foods. However, it is important to understand that symptom improvement make take some time, and results vary from individual to individual. Removing reactive foods from the diet can sometimes result in withdrawal symptoms like headaches, tiredness, irritability and hunger.

Why Test?

Good health has a lot to do with maintaining balance; the right balance of work and play, the right balance of nutrients in the diet, and the right kinds of foods.

Undiagnosed food sensitivities may contribute to symptoms and biochemical changes that result in illness.

Learn More About Food Sensitivities

To learn more about food sensitivities, you can book a free 15 minute meet and greet appointment to discuss your questions and learn how to live a vibrantly, healthy life.


Information provided by this article is for educational purposes only. It is not meant as medical advice and any treatment decisions should be made with the knowledge or consent of your healthcare professional. Consultation with a Naturopathic Doctor or other primary care provider is recommended for anyone suffering from a health problem.


Dr. Sylvia Santos is a Naturopathic Doctor practicing in Vaughan, Ontario, Canada. She is a passionate about health promotion and encourages her patients and readers to embrace their full health potential. You can follow Dr. Santos on InstagramFacebook and Twitter or contact her at

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