One of the most common questions I get asked in clinic is: Should I do a food intolerance test?
It makes sense. If food seems to trigger your symptoms, it feels logical to test for the culprits. But most of the time, it is not actually the food that is the core problem. More often, the real issue lies in how your gut is functioning and the balance of your microbiome. That is why food intolerance testing is rarely my first step.
The Problem With Intolerance and Allergy Testing
There are different tests available that look at how your immune system responds to foods, with the most common being IgE and IgG testing.
IgE allergy testing: IgE antibodies are linked to true food allergies, the kind that can cause hives, swelling, or even anaphylaxis. This type of testing is medically recognised and evidence-based. However, even IgE is not flawless. Blood tests can sometimes show false positives or sensitisation, where your immune system recognises a food but you do not actually react when you eat it. That is why a detailed clinical history, and sometimes oral food challenges, remain the gold standard for diagnosing allergies.
IgG intolerance testing: IgG measures delayed responses, where reactions can occur hours or days after eating. IgG can be valuable in guiding elimination or rotation diets, particularly for chronic or complex conditions involving gut, skin, neurological, or inflammatory symptoms. However, IgG results alone do not tell the whole story. Elevated levels may sometimes simply reflect exposure or tolerance rather than a true intolerance.
Hair or bio-resonance testing: These are not supported by strong scientific evidence. Results are often inconsistent and do not reliably line up with clinical symptoms.
So while IgE and IgG can both offer insight in certain cases, they are rarely my starting point. For most people, food reactions are not simply about the food. They are about the state of the gut.
And an important note: doing any of these tests without professional guidance can lead to unnecessary food restrictions, added stress, and even harm to your microbiome. This is something I see often when people have tested themselves and implemented long exclusion lists without looking at the bigger picture.
Why It Is Often the Gut, Not the Food
In my experience, food reactivity is usually a symptom of an unhappy gut, not the root cause.
If your gut lining is more permeable than it should be, your microbiome is out of balance, or you have SIBO, your body is much more likely to react to a wide range of foods. That does not mean those foods are bad forever. It means your gut needs support and repair.
Once we calm inflammation, restore gut barrier function, and support a healthier microbiome, many food sensitivities naturally improve or disappear.
What I Focus On Instead
Rather than starting with intolerance testing, I recommend exploring gut health with investigations like:
- SIBO breath testing, ideally including lactulose, glucose, and fructose
- Comprehensive gut microbiome stool analysis
- Intestinal permeability testing
These tests help show why your body is reacting. From there, we can create a personalised gut repair plan that tackles the root cause instead of just removing foods from your diet.
Only if symptoms persist after gut healing do I sometimes consider food intolerance or allergy testing. And in those cases, I always combine results with a guided elimination and reintroduction process so we know what is truly relevant for you.
My Advice If You Are Considering Food Testing
- Be cautious about spending big on intolerance tests before addressing gut health.
- If you already have results, do not panic. It does not mean you need to cut out every food listed forever.
- Work with a practitioner who can interpret the results in the bigger picture of your gut health.
The Bottom Line
Food intolerance testing can sometimes play a role, but for most people, it is not the first or most important step. By focusing on healing the gut itself, we often see food sensitivities improve dramatically without the overwhelm of long do-not-eat lists.
Because food is not the enemy. A resilient gut is one of the best ways to enjoy a wide and nourishing diet again.
Curious about what is really driving your food reactions? Book a consult or explore our consult and testing packages and testing bundles to get to the root cause.
References
- Stapel SO, et al. Testing for IgG4 against foods is not recommended as a diagnostic tool: EAACI Task Force Report. Allergy. 2008;63(7):793-796.
- Carr S, et al. Food allergy and intolerance. Medicine. 2018;46(3):192-198.
- Sicherer SH, Sampson HA. Food allergy: A review and update on epidemiology, pathogenesis, diagnosis, prevention, and management. J Allergy Clin Immunol. 2018;141(1):41-58.
- Uhde M, et al. Markers of non-celiac wheat sensitivity in patients with irritable bowel syndrome. Gut. 2016;65(12):1930-1937.
- Bischoff SC. Food allergies in irritable bowel syndrome: Sensitization to common food antigens does not correlate with symptoms. Am J Gastroenterol. 2004;99(4):720-728.
Written by Naturopath Chae
