What if the foods you eat every day, even healthy foods, were contributing to inflammation, headaches, digestive issues, or fatigue without you realizing it? Food sensitivities are often misunderstood because they don’t cause immediate reactions like food allergies. Instead, they trigger delayed immune responses that can occur hours to days after eating, making it difficult to link them to a specific food without testing. The M2 Institute Food Sensitivity Panel assesses IgG Type III delayed hypersensitivity reactions, which are immune responses that occur hours to days after eating certain foods and may contribute to digestive issues, headaches, fatigue, and inflammation.
What Is an IgG Food Sensitivity?
IgG food sensitivities occur when the immune system reacts to certain foods after repeated exposure. These reactions are delayed, typically appearing 3 hours to 3 days after eating, and are often dependent on how much of the food was consumed.
When this happens, the immune system produces IgG antibodies, which are part of the adaptive immune system that normally helps protect us from foreign invaders. However, in this case, the immune system may start reacting to food proteins as if they were a threat.
Common symptoms of food sensitivities include:
- Digestive issues
- Headaches or migraines
- Mood or behavior changes
- Attention and focus issues
- Fatigue
- Skin issues
- Chronic inflammation
Because symptoms are delayed, food sensitivities can be difficult to identify without testing.
The Gut Connection: Why Food Sensitivities Develop.
Most IgG food sensitivity reactions originate in the gastrointestinal tract. When the gut becomes inflamed, it can lead to intestinal permeability, often referred to as “leaky gut.”
This can happen due to:
- Poor digestion
- Imbalance of gut bacteria
- Excess alcohol intake
- Certain medications
- Chronic inflammation
When the gut lining becomes more permeable, small food particles can pass through the gut wall and enter the bloodstream. The immune system then responds by producing IgG antibodies against those food particles, which can lead to food sensitivities and inflammation.
Food Sensitivity vs. Food Allergy: What’s the Difference?
When you visit an allergist for food allergies, they typically perform a skin prick test that measures IgE Type I reactions.
Here’s how IgE food allergies work:
- Reaction occurs within seconds to 30 minutes
- Not dependent on how much food you eat
- Can affect multiple organs
- Can be severe or life-threatening
- Symptoms may include hives, swelling, trouble breathing, or anaphylaxis
In contrast, IgG food sensitivities:
- Are delayed (hours to days)
- Often related to the amount eaten
- Typically cause digestive issues, headaches, fatigue, or inflammation
- Are not life-threatening but can contribute to chronic health issues
Why IgG Tests Can Show Negative or Unexpected Results.
IgG testing measures antibodies produced only when you regularly eat a food. If you haven’t eaten a food recently, your body may not be producing antibodies, and the test may show a negative result, even if you previously reacted to that food.
On the other hand, sometimes people test positive for foods they don’t remember eating. This may happen due to cross-reactivity, in which the immune system reacts to proteins similar to those in other foods you commonly eat.
Additionally, if a food has not been eaten for several weeks or months, IgG antibody levels may decline, and the test may no longer show a reaction.
Be Proactive.
Food sensitivities can be an important piece of the puzzle when addressing digestive issues, headaches, mood and focus concerns, fatigue, skin conditions, and chronic inflammation. Understanding the difference between food allergies (IgE) and food sensitivities (IgG) can help guide appropriate testing, dietary changes, and a treatment plan for long-term health improvements.
Identifying and temporarily removing reactive foods, while also supporting gut health and digestion, is often one of the most effective ways to reduce inflammation and improve overall well-being.
If you are interested in food sensitivity testing, test kits are available to order through our online store for in-store pickup or direct home delivery. We also offer consultations to review your results, help you interpret the report, and create a personalized plan to support gut health and reduce food sensitivity reactions.
Jessica Wilhelm
Director of Wellness, Peoples Wellness and Rx