Food Allergies, Intolerance, and Sensitivity: What’s The Difference?

In the world of nutrition and wellness, terms like food allergy, food intolerance, and food sensitivity are often used interchangeably. But it important to know—these are not the same thing. Understanding their key differences is essential to uncovering hidden causes of symptoms, healing your body from the inside out, and restoring your relationship with food.

Let’s explore what sets these reactions apart, how they show up in the body, and what we can do about them from a root-cause, functional perspective.

Quick Overview: What’s the Difference?

Feature	Food Allergy (IgE)	Food Sensitivity (IgG/IgA)	Food Intolerance (Non-Immune)
Immune Involvement	Yes (IgE antibodies)	Yes (IgG or IgA antibodies)	No
Reaction Speed	Immediate (minutes to hours)	Delayed (hours to days)	Gradual (often dose-dependent)
Duration of Reaction	1–2 days	Up to 21 days	Variable
Common Symptoms	Hives, swelling, anaphylaxis	Fatigue, bloating, joint pain	Gas, bloating, diarrhea
Root Cause	Immune hypersensitivity	Gut barrier dysfunction ("leaky gut")	Enzyme deficiency or irritant
Common Triggers	Peanuts, shellfish, milk	Gluten, dairy, soy, eggs	Dairy (lactose), alcohol, histamine
Testing Methods	Skin prick, IgE blood test	IgG/IgA blood tests, elimination trial	Breath test, elimination trial
Reversible?	Typically, though not always, lifelong	Often reversible with gut healing	Often manageable or reversible

1) Food Allergies: Acute and Immediate Reactions (IgE)

Food allergies are immune system reactions that occur when the body misidentifies a food protein as a threat. These reactions are mediated by Immunoglobulin E (IgE) antibodies and usually occur within minutes to hours of exposure.

Common Symptoms:

• Hives or rash

• Swelling (especially lips, tongue, or face)

• Trouble breathing, coughing, wheezing

• Sneezing, runny nose, watery eyes

• Vomiting, diarrhea, or stomach pain

In severe cases, food allergies can cause anaphylaxis, a life-threatening reaction that requires immediate medical attention.

Common Triggers:

• Peanuts and tree nuts

• Shellfish and fish

• Milk, eggs, soy, wheat

Testing:

These are typically confirmed via IgE blood testing or skin prick tests. Allergies are often permanent and could require complete avoidance of the offending food while working on healing the body as a whole.

2) Food Intolerance: A Digestive Problem, Not an Immune One

Food intolerances do not involve the immune system. Instead, they arise when the body lacks the enzymes or cofactors necessary to properly digest certain foods or food components. The response is usually dose-dependent, meaning small amounts may be tolerated.

Common Symptoms:

• Bloating and gas

• Diarrhea or constipation

• Heartburn or reflux

• Headaches or irritability

• Flushing, congestion, fatigue

Common Triggers:

• Lactose (from dairy)

• Histamines (aged cheeses, wine)

• Gluten (non-celiac gluten intolerance)

• Additives, preservatives, sulfites

• Alcohol, caffeine, chocolate, citrus

Functional Insight:

We often identify intolerances via elimination diets, food-mood journaling, and sometimes breath tests (e.g., for lactose or fructose). Supporting digestive enzyme production and overall gut function can greatly reduce symptoms.

3) Food Sensitivities: Delayed, Chronic Immune Reactions (IgG/IgA)

Food sensitivities are immune reactions—but they’re more chronic, subtle, and delayed than allergies. These involve IgG or IgA antibodies and often stem from increased intestinal permeability, or "leaky gut." This condition allows partially digested food proteins to escape into the bloodstream, where they trigger an inappropriate immune response systemically.

Common Symptoms:

• Migraines and headaches

• Fatigue and brain fog

• Anxiety or mood swings

• Bloating, gas, or IBS symptoms

• Skin issues (acne, eczema, hives)

• Joint or muscle pain

• Sinus congestion, post-nasal drip

• Unexplained weight gain or loss

Common Triggers:

• Gluten-containing grains (wheat, barley, rye, spelt)

• Dairy

• Eggs

• Soy

• Tree nuts and peanuts

• Corn

Functional Insight:

Food sensitivities are best identified with IgG/IgA testing or elimination protocols. The good news? With targeted gut healing and immune support, many food sensitivities are reversible.

Functional Medicine: Addressing the Root Cause

Rather than just avoiding trigger foods forever, we aim to restore the integrity of the gut, reduce inflammation, and calm the immune system. Here’s how we dig deeper:

Functional Labs We May Use:

• Food Sensitivity Panels (IgG, IgA, MRT)

• GI-MAP or GI Microbiome (gut microbiome, infections, leaky gut markers)

• Organic Acids Test (OAT) for nutrient deficiencies and detox support

  
  

Your Path to Healing

At Purely Rooted Nutrition, we go beyond symptom suppression. Our mission is to identify and address why your body is reacting—whether that means rebuilding gut integrity, supporting digestion, rebalancing your immune response, or improving resilience to environmental triggers.

We offer:

• Personalized elimination protocols

• Gut restoration and enzyme support

• Functional testing for food reactions and root causes

• Clinical-grade supplements and therapeutic nutrition plans

Ready to Get Clarity?

Whether you're dealing with bloating, brain fog, joint pain or chronic fatigue, the food you're eating could be contributing more than you think.

Schedule your free 15-minute consult to discuss your symptoms and see if food sensitivity testing is right for you. Or explore our functional testing services to learn more about how we uncover what’s happening beneath the surface.

Food Allergy, Food Sensitivity, Food Intolerance