If you’ve ever felt bloated, sluggish, or foggy after a meal, but couldn’t quite pinpoint why, you’re not alone. Many people experience ongoing symptoms that are often linked to their body’s reaction to certain foods. These reactions aren’t always straightforward and can show up hours or even days after eating, making them difficult to identify.

That’s where food intolerance and sensitivity testing come in. But with a growing number of tests available, like IgG, IgE, and Cyrex panels, alongside elimination diets, it’s easy to feel overwhelmed. In this guide, we’ll break down the different types of food reaction tests, how they work, and who they’re best suited for. Whether you’re dealing with digestive discomfort, skin issues, fatigue, or just want clearer answers about your health.

Food Intolerance vs Food Allergy vs Sensitivity

When it comes to adverse reactions to food, the terms intolerance, allergy, and sensitivity are often used interchangeably, but they’re very different processes within the body.

Food Allergy (IgE)

A food allergy involves an immediate immune system response, usually within minutes of exposure. This reaction is driven by IgE antibodies and can cause symptoms such as hives, swelling, difficulty breathing, or even anaphylaxis. Common allergens include peanuts, shellfish, and eggs. Because these reactions can be severe or life-threatening, diagnosis and management should always be guided by a medical professional.

Food Sensitivity

Food sensitivities are typically non-immune reactions and usually involve the digestive system. They occur when the body lacks certain enzymes needed to break down specific foods, such as the enzyme lactase for digesting lactose in dairy. Symptoms like bloating, gas, diarrhoea, or cramping can develop gradually and depend on the amount consumed.

Food Intolerance (IgG and Others)

Food intolerances involve a delayed immune response, often driven by IgG antibodies or other immune pathways. Symptoms may take hours or even days to appear, making them difficult to link to specific foods. These reactions are often more systemic, contributing to fatigue, headaches, joint pain, skin issues, or mood disturbances.

IgE Testing – Allergy Testing

• What is it? IgE testing identifies immediate allergic reactions triggered by Immunoglobulin E antibodies. These reactions typically occur within minutes of eating the offending food.

• Who it’s for: Ideal for those experiencing classic allergy symptoms like hives, swelling, difficulty breathing, or anaphylaxis.

• Pros: Clinically validated and reliable for diagnosing true food allergies. Results are usually straightforward and medically actionable.

• Cons: IgE tests do not detect delayed reactions or food sensitivities, so they may miss issues causing more subtle or chronic symptoms.

IgG Food Sensitivity Testing

• What is it? This test measures Immunoglobulin G (IgG) antibodies that may form in response to specific foods, potentially indicating delayed food sensitivities. Unlike immediate allergic reactions, IgG responses can take hours or even days to manifest.

• Symptoms it may help with: Chronic bloating, fatigue, brain fog, joint pain, migraines, skin issues, and IBS-like symptoms.

• Pros: Non-invasive and easy to complete at home. Helpful for uncovering hidden triggers behind persistent, unexplained symptoms.

• Cons: IgG testing remains debated in mainstream medicine; results may reflect recent food exposure rather than intolerance. Best used alongside clinical insight and symptom tracking.

Cyrex Array Testing

• What is it? Cyrex Labs offers highly specialised tests that go beyond the sensitivity (IgG) testing. Their panels measure multiple immune markers, including IgG, IgA, and IgM, allowing for a more detailed picture of immune reactivity.

• What it tests: Cyrex offers advanced food reactivity tests, including panels that assess immune responses to 90 or 180 foods, gluten sensitivity, and cross-reactivity – all designed to uncover hidden triggers behind chronic symptoms.

• Pros: Comprehensive and precise. Cyrex testing is particularly advanced in detecting complex immune reactions and cross-reactivity, such as how your body may react to foods that mimic gluten.

• Ideal for: Individuals with autoimmune conditions, unexplained chronic symptoms, or suspected gluten sensitivity that persists despite a gluten-free diet.

Elimination Diets

• What is it? An elimination diet involves temporarily removing common trigger foods from your diet to identify which ones might be causing symptoms.

• How it works: Foods like gluten, dairy, soy, eggs, and sometimes nuts or nightshades are excluded for several weeks. They are then slowly reintroduced, one at a time, while monitoring your body’s response.

• Pros: Often considered the gold standard in identifying food sensitivities. It’s cost-effective, doesn’t require lab testing, and can provide powerful insight into your body’s unique reactions.

• Cons: It’s time-consuming, requires dedication and planning, and relies on subjective symptom tracking. It’s also not a diagnostic tool and should ideally be done under professional guidance.

A Note on Inhalant Allergies

Inhalant allergies are among the most common allergic conditions, affecting around one in four people in the UK. They occur when the immune system overreacts to airborne substances, such as pollen, dust mites or animal dander, by producing IgE antibodies. This immune response releases chemicals like histamine, leading to symptoms including sneezing, nasal congestion, itchy eyes, coughing, and, in more severe cases, wheezing or breathlessness.

Common inhalant allergens include:

• Tree and grass pollen

• House dust mites

• Mould spores

• Pet dander (cats, dogs)

• Insect particles and environmental chemicals

Which Test is Right for You?

Choosing the right test depends on your symptoms, health history, and goals. Here’s a quick guide:

• Digestive issues (bloating, diarrhoea, IBS): Start with an IgG test or an elimination diet. If symptoms are severe or persistent, consider combining with gut health testing (like GI-MAP). It’s important to note than an elimination diet is best done with a practitioner.

• Skin problems (eczema, acne, hives): IgE tests may be appropriate for immediate reactions; IgG or Cyrex may offer insight for delayed or autoimmune-linked symptoms.

• Autoimmune conditions or chronic inflammation: Cyrex tests offer the most specific data on immune system reactivity and cross-reactivity.

• Budget or time constraints: Elimination diets are low-cost and effective, though they require more time and effort. IgG tests offer quicker answers with minimal disruption.

Remember, lab results are only part of the puzzle. Clinical interpretation by a qualified practitioner is essential for meaningful insights and creating a sustainable, personalised plan.

Allergy Testing with Smart Nutrition

Smart Nutrition offers a trusted, expert-led range of allergy and intolerance tests designed to help you uncover what your body reacts to, quickly and accurately. Whether you’re dealing with digestive issues, skin conditions, or unexplained fatigue, we offer a wide variety of testing options, from IgE allergy tests to IgG intolerance panels and advanced Cyrex testing.

With clear results, expert support, and fast turnaround times, Smart Nutrition makes it easy to take control of your health.