Food sensitivities, IgE and IgG testing


Do you think certain foods are messing with your health and making you sick? Are you periodically suffering from symptoms like bloating, brain fog, poor sleep, poor digestion, skin rashes, mood issues, hormonal issues, joint pain, and many others? It may be because of certain food sensitivities.

When we think of allergies or food sensitivities, we generally think of peanut, shellfish, or other life-threatening allergies with overt symptoms, but one could be reacting to a whole array of food, even the so-called healthy food, with hidden symptoms, as mentioned above. Food sensitivities might affect you immediately or it might take a few days. This can make it difficult to determine what foods might be causing various problems.

70% of your immune system lies in the gut- its job is to avoid any pathogen from entering your body and causing any harm. It’s a defense system generated by the body to protect itself. When one has a leaky gut or intestinal permeability, the proteins from foods can leak out into the bloodstream and be marked as antigens by your immune system. The immune system produces immunoglobulins which are antibodies in response to those antigens. IgE antibody test gives immediate reactions like hives, swelling of the face, lips, tongue, or in extreme cases throat called anaphylaxis, which is a life-threatening situation. These reactions almost happen immediately and it’s easier to identify which food is causing the reaction pretty easily. But in food sensitivity, the reactions are delayed. These are often measured with the IgG and IgA antibody test. The symptoms can range so broadly between weight gain, depression, anxiety, hormonal issues, sleep, headaches, and mood changes, that most people do not associate these with food sensitivities or allergic reactions.

An example of this would be a nightshade sensitivity that causes eczema to flare up within 1-3 days of consuming foods like tomatoes, eggplant, or peppers.

However, the IgG sensitivity test is not a gold standard for testing sensitivities, because it can give a lot of false positives. For IgG antibodies to show up through IgG testing, a person needs to be actively eating the foods that they’re testing for.

What tends to happen is that if someone is struggling with their gut health and has this test run, the results will come back with all of the foods they have recently been eating, highlighted in the blood work as positives. But it’s highly unusual and unrealistic that someone could be reacting to so many different foods!

Food sensitivities can develop when the gut lining becomes permeable or leaky, leading to a condition called as the leaky gut. In this situation, food antigens can make their way through the intestinal lining, and into circulation, where our immune system is put on high alert, creating antibodies to fight these “foreign invaders.” These antigens are meant to stay within the gut and not make their way through the intestinal lining, and into the bloodstream.

This is why IgG testing can be unreliable and not of much use, as it’s very unrealistic that someone could be reacting to all the foods they are consuming. Healing the gut will ensure fewer antigens being leaked into the bloodstream, reducing the immune response and hence lessening food sensitivities.

Another factor to address that causes food sensitivities and intolerances, is eating the same foods every day. Most people are creatures of habits and routine- especially food. For some, it could be because of the comfort a certain food brings, or for others, they simply don’t want to wreck their brains in meal-planning every day. But eating the same foods can cause nutrient deficiencies over time and also reduces the diversity of the gut microbiome, as different bacteria thrive on different foods. Eating the same foods can completely wipe out certain bacteria that it needs to thrive. Without the diversity of bacteria in the gut microbiome, we are more susceptible to gut dysfunctions.

In addition, we often crave foods we are intolerant to. This is because the bad bacteria love foods that rot in our gut or that our body can’t digest since this rotting food feeds unhealthy gut bacteria and can create more unhealthy gut bacteria to house our gut causing a condition called dysbiosis.

Have you ever eaten food and not felt well afterward—only to want it again the next day? Even though you may get bloated, constipated, have a headache, or fatigued every day after eating that food, you’re in semi-denial. When we eat the same thing every day, we become more at risk for developing food intolerances since, over time, our body can develop an “immune response” to the same proteins from these foods it gets every day.

Repetitive exposure to the same limited foods creates a leaky gut and an immune response to an antigen that escapes in the bloodstream, as discussed above, causing many different food allergies.


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Functional Nutritionist & Functional Medicine Practitioner

Smriti is a leading Health Coach and Functional Medicine Practitioner, based out of Gurgaon, India.