Food Intolerance Test
Feb 4, 2026
Food Intolerance Test
A food intolerance test measures IgG antibodies to various foods, helping identify potential triggers for symptoms like bloating, digestive discomfort, fatigue, headaches, and skin problems—with results best used to guide structured elimination diets rather than as definitive diagnoses. Unlike true allergies (IgE-mediated, potentially life-threatening), food intolerances cause delayed, uncomfortable but not dangerous reactions.
At Blood Test London, food intolerance testing costs from £295 with results in 2-3 days.
Food Intolerance vs Food Allergy
Feature | Food Intolerance | Food Allergy |
|---|---|---|
Immune mechanism | IgG or non-immune | IgE-mediated |
Reaction timing | Hours to days later | Minutes to 2 hours |
Severity | Uncomfortable | Can be life-threatening |
Amount | Often dose-dependent | Tiny amounts trigger |
Symptoms | Digestive, fatigue, headaches | Hives, swelling, anaphylaxis |
Testing | IgG, elimination diet | IgE blood test, skin prick |
Important: Our IgG food intolerance test is different from IgE allergy testing. If you suspect a true allergy (immediate reactions, swelling, breathing difficulty), you need allergy testing instead.
Common Food Intolerance Symptoms
Digestive
Bloating
Abdominal pain
Gas and flatulence
Diarrhoea or constipation
Nausea
IBS-like symptoms
Beyond Digestive
Fatigue and low energy
Headaches and migraines
Brain fog
Joint aches
Skin problems (eczema, acne)
Mood changes
The Challenge
Symptoms appear hours or days after eating, making it hard to identify triggers without testing.
What Our Test Covers
Standard Panel (93 Foods) - £395
Dairy & Eggs
Cow's milk, cheese, yoghurt, egg white, egg yolk
Grains & Gluten
Wheat, gluten, barley, rye, oats, rice, corn
Meats
Beef, chicken, pork, lamb, turkey
Fish & Seafood
Cod, salmon, tuna, prawns, crab
Fruits
Apple, banana, orange, strawberry, grape, pineapple, and more
Vegetables
Potato, tomato, carrot, onion, broccoli, spinach, and more
Nuts & Seeds
Almond, peanut, cashew, walnut, sesame, sunflower
Others
Soya, yeast, coffee, cocoa, honey
Comprehensive Panel (200+ Foods) - £545
Extended panel including herbs, spices, and less common foods.
Understanding Your Results
IgG Levels
Result | Meaning | Action |
|---|---|---|
Negative | No IgG reaction | Food likely tolerated |
Low positive | Mild reaction | Consider reduction |
Moderate positive | Notable reaction | Trial elimination |
High positive | Strong reaction | Priority elimination |
How to Use Results
Don't eliminate everything at once
Start with highest positives
Eliminate for 4-6 weeks
Monitor symptoms
Reintroduce one food at a time
Observe for reactions
Important Considerations
What IgG Testing Can and Can't Do
Can help with:
Guiding elimination trials
Identifying potential triggers to investigate
Providing a starting point when overwhelmed
Limitations:
IgG can simply reflect foods you eat often
Not all positives cause symptoms
Some intolerances aren't IgG-mediated (e.g., lactose intolerance is enzyme deficiency)
Gold standard remains elimination diet + reintroduction
The Scientific Debate
IgG food testing is controversial in mainstream medicine. Some experts argue IgG reflects exposure, not intolerance. However, many practitioners find it clinically useful when interpreted correctly—as a guide, not a diagnosis.
Alternative and Complementary Tests
If You Suspect | Better Test |
|---|---|
Lactose intolerance | Lactose breath test |
Coeliac disease | Coeliac blood test (tTG antibodies) |
True food allergy | IgE allergy blood test |
SIBO | Breath test |
Fructose intolerance | Fructose breath test |
We can advise which tests are most appropriate for your symptoms.
Book Your Food Intolerance Test
Price: From £295
Results: 2-3 days
Doctor review: A doctor always reviews every result with interpretation and advice
Fasting required: No
Phone: 020 3951 3429
FAQ
Are food intolerance tests accurate?
They accurately measure IgG antibodies. The debate is about what elevated IgG means clinically. We recommend using results to guide elimination trials.
Should I stop eating all positive foods?
No—start with the highest positives and eliminate systematically. Many positives may not be causing symptoms.
How is this different from allergy testing?
Allergy testing measures IgE (immediate, potentially dangerous reactions). Intolerance testing measures IgG (delayed, uncomfortable reactions).
Why not just do an elimination diet without testing?
You can, but it's very restrictive and hard to maintain. Testing helps prioritise which foods to eliminate first.
How long until I feel better?
If you've identified true triggers, many people notice improvement within 2-4 weeks of elimination.
Blood Test London by The Wellness. Food intolerance testing from £295, results in 2-3 days.