Food Sensitivity vs Food Allergy vs Food Intolerance: The Key Differences

In This Guide

• Quick Comparison Table
• Food Allergy (IgE-Mediated)
• Food Sensitivity (Mediator-Mediated)
• Food Intolerance (Enzymatic)
• How Each One Is Tested
• Can You Have More Than One?
• Symptom-Based Decision Guide
• Next Steps

A food allergy is a fast immune response. When you eat a trigger food, your immune system fires off IgE antibodies that tell your mast cells to release histamine and other chemicals. This happens fast, usually within minutes to two hours. Symptoms range from hives to life-threatening anaphylaxis.

Key characteristics:

• Immediate. You know when you’re having an allergic reaction because it happens fast.
• Trace amounts matter. Even cross-contamination in a shared kitchen causes a reaction for someone with a peanut allergy. That’s why epipens exist.
• Often lifelong. Most people never outgrow true food allergies, though kids sometimes outgrow milk and egg allergies.
• Well-understood by conventional medicine. Allergists use skin prick tests and IgE blood panels to find these. Your doctor already knows how to look for this.

The top 9 food allergens (required by FALCPA to be declared on food labels): milk, eggs, fish, shellfish, tree nuts, peanuts, wheat, soy, and sesame.

A food sensitivity is a delayed immune response. Instead of triggering IgE antibodies and histamine, your immune system releases inflammatory mediators like prostaglandins, cytokines, and leukotrienes when it comes in contact with specific foods or chemicals. The Mediator Release Test (MRT) is designed to detect this exact reaction.

Key characteristics:

• Delayed. Symptoms appear 4 to 72 hours after eating the trigger. This delay is why you haven’t figured out your sensitivities on your own. You just can’t connect Tuesday’s garlic to Thursday’s migraine by guessing.
• Widespread symptoms. Allergies mostly affect your skin and airways, but sensitivities cause headaches, joint pain, brain fog, fatigue, digestive issues, and skin problems. You often get several of these at the same time.
• Dose-dependent. A tiny bit of a moderately reactive food won’t always cause symptoms, but eating a full serving or having it several days in a row absolutely will.
• Includes chemical additives. The MRT tests 27 chemicals, like citric acid, MSG, soy lecithin, food dyes, and preservatives. Standard allergy tests skip these completely.
• Can improve. When you follow the LEAP protocol, many of your sensitivities go away as your gut inflammation drops and your immune system calms down.

This reaction falls right in the gap between traditional allergy tests and your doctor telling you nothing is wrong. It is real, it is measurable, and it is the exact reason you have chronic symptoms that don’t show up on standard blood work.

A food intolerance is a digestive problem, not an immune response. Your body just lacks the enzyme it needs to break down a specific part of your food. That undigested food passes into your large intestine, where your gut bacteria ferment it. This produces gas, bloating, cramping, and diarrhea.

Key characteristics:

• Purely digestive. Symptoms stay in your GI tract, like gas, bloating, diarrhea, and cramping. Intolerances do not cause migraines, joint pain, brain fog, or skin issues.
• Highly dose-dependent. If you are lactose intolerant, you probably handle a splash of milk in your coffee fine but react badly to a whole glass. The more you eat, the worse you feel.
• No immune involvement. Blood tests won’t show anything because your immune system isn’t involved at all. Skin prick tests come back negative. The MRT only shows a reaction if you also have a separate immune sensitivity to that food.
• Enzyme supplements help. Lactase pills help lactose-intolerant people eat dairy. We don’t have supplements like that for true food sensitivities because the immune system is driving the problem, not a lack of enzymes.

Common examples include lactose intolerance (lack of lactase enzyme), fructose malabsorption, histamine intolerance (lack of DAO enzyme), and FODMAP sensitivity (covered in our IBS elimination diet guide).

What About IgG Testing?

Many wellness companies sell IgG food panels that measure IgG antibodies to foods. But IgG antibodies just show exposure, not reactivity. Having IgG antibodies to a food simply means your immune system has seen it before. That is perfectly normal for any food you eat regularly. Major allergy and immunology organizations recommend against using IgG panels for food sensitivity diagnosis. For a detailed comparison, see our MRT vs IgG vs Skin Prick guide.

• A true allergy to shellfish (IgE-mediated, carries an epipen)
• A sensitivity to citric acid and cane sugar (mediator-mediated, causes chronic migraines)
• An intolerance to lactose (enzymatic, causes bloating with dairy)

PRACTITIONER INSIGHT

When the digestive tract comes in contact with a food sensitivity it sparks an inflammatory cascade that causes widespread damage over time to the gut, the immune system and nearly every other system and organ in the body. All disease starts in the gut. Addressing food sensitivities is a vital part of preventing inflammation and protecting the entire body from imbalance.

— Kerry Watson, NTP, RWP • About Kerry

References: Kinashi, Y., & Hase, K. (2021). Partners in Leaky Gut Syndrome: Intestinal Dysbiosis and Autoimmunity. Frontiers in Immunology, 12, 673708. • Bull, M. J., & Plummer, N. T. (2014). Part 1: The Human Gut Microbiome in Health and Disease. Integrative Medicine, 13(6), 17–22.

Related Resources

• Elimination Diet for IBS: 3 Approaches Compared
• MSG and Food Sensitivity: What the MRT Panel Reveals
• Lowest-Trigger Grocery Products: 20,000 Products Analyzed
• What Does “Natural Flavors” Actually Mean?
• Hidden Chemical Triggers in Everyday Foods