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Evidence-first · London

Food intolerance testing, without the supplement sales pitch.

The commercial IgG food intolerance tests you have seen advertised at £150 to £350 are not recommended by BSACI, EAACI or NICE. Here is what the evidence-based pathway looks like, and where to get it done properly in London.

Evidence position

IgG food intolerance tests are not clinically validated.

The British Society for Allergy and Clinical Immunology (BSACI), the European Academy of Allergy and Clinical Immunology (EAACI) and NICE all advise against using IgG-based food panels, including the widely marketed YorkTest, Cambridge Nutritional Sciences, Lifelab, Allergy UK-branded and Optima Health panels, to diagnose food intolerance. IgG antibodies to food are a normal marker of immune exposure to what you eat, not a sign of intolerance or allergy.

Elimination diets built from a positive IgG panel routinely remove foods a patient tolerates perfectly well. The results are unnecessary dietary restriction, avoidable anxiety around eating, and, in some cases, real nutritional deficiency. Some clinics that promote these tests also sell the supplements, probiotics and follow-up consultations that the results appear to justify. That conflict of interest is worth naming.

IgG panels are not recommended for diagnosing food intolerance.

What actually gets tested

The tests with real diagnostic value.

Ordered when the history points that way, not as a shotgun panel. Histamine intolerance and DAO enzyme testing remain controversial and should be treated as such.

Test How it is done
IgE food allergy testing Skin prick test plus specific IgE blood test, oral food challenge in a supervised setting
Coeliac disease serology Anti-tTG IgA plus total IgA plus endomysial IgA, HLA-DQ2/DQ8 if borderline, then duodenal biopsy while still eating gluten if positive
Lactose intolerance Hydrogen breath test after a measured lactose load, or LCT-13910 genetic test for adult-type hypolactasia
Fructose malabsorption Hydrogen breath test after fructose load
Small intestinal bacterial overgrowth (SIBO) Hydrogen and methane breath test, glucose or lactulose substrate
FODMAP intolerance (functional) Structured low-FODMAP elimination and reintroduction over four to six weeks, led by a Monash-trained dietitian
Alpha-gal syndrome Specific IgE to galactose-alpha-1,3-galactose after suspected tick bite reactions

Component-resolved IgE panels (ISAC, ALEX) are useful when a broad allergy screen is warranted. Dietitian consultations run £150 to £280 per session.

The pathway

What is actually recommended, in order.

A staged approach: history first, structured exclusion second, targeted testing only where the history points.

  1. 01

    History and a food and symptom diary

    Two to four weeks of what you ate, when, and what happened. This is the single most useful diagnostic step, and it costs nothing.

  2. 02

    Exclude coeliac, IBD and endocrine disease

    Blood tests for coeliac, inflammatory markers, ferritin, thyroid function and, where indicated, faecal calprotectin. These change management. IgG panels do not.

  3. 03

    Structured elimination and reintroduction

    A dietitian removes suspected triggers for four to six weeks, then reintroduces them one at a time in measured doses. This is the only reliable way to identify a true food-driven symptom.

  4. 04

    Low-FODMAP trial for IBS

    With a Monash-trained dietitian, in three phases: elimination, reintroduction, personalisation. Not a long-term diet.

  5. 05

    Allergy referral if reactions are severe

    Any suggestion of anaphylaxis, angioedema, breathing difficulty or a reaction within minutes of eating goes to a BSACI allergy clinic, not a wellness lab.

Related guides

Frequently asked

The questions people ask most often.

  • What's the evidence against IgG food intolerance tests?

    IgG antibodies to food are a normal marker of dietary exposure, not of intolerance or allergy. The British Society for Allergy and Clinical Immunology (BSACI), the European Academy of Allergy and Clinical Immunology (EAACI) and NICE all advise against using IgG panels to diagnose food intolerance. Elimination diets built from these results can cause unnecessary restriction and nutritional deficiency without clinical benefit. They are not recommended.

  • Will private medical insurance cover food intolerance testing?

    Insurers reimburse evidence-based investigation when it is medically indicated: allergy testing under an allergist, coeliac serology and endoscopy under a gastroenterologist, breath testing for lactose, fructose or SIBO. Commercial IgG panels and finger-prick home kits are almost never covered because they are not clinically validated. Bupa, AXA, Vitality and Aviva follow this line.

  • Should I test for coeliac disease before cutting out gluten?

    Yes, and this matters. Coeliac serology only works if you are still eating gluten regularly, at least one meal a day, for six weeks beforehand. Cutting gluten first can produce a false negative and delay a real diagnosis by months. Anti-tTG IgA with a total IgA is the first-line test.

  • How do I test for lactose intolerance properly?

    A hydrogen breath test after a measured lactose load is the standard clinical test, done at a specialist GI unit. The LCT-13910 genetic test tells you whether you carry the adult-type lactase persistence variant, which is useful context but does not replace the breath test for current symptoms.

  • Can I just do an elimination diet myself?

    You can, and a food and symptom diary is genuinely useful. What is best avoided is a long, unstructured elimination without reintroduction, because that leads to progressively narrower eating without ever confirming the trigger. A registered dietitian keeps it structured, safe and time-limited.

  • Why see a dietitian rather than a nutritional therapist?

    A registered dietitian (RD) is a regulated healthcare professional trained to manage clinical conditions. Nutritional therapy is not statutorily regulated in the UK, and the two roles are not equivalent. For a suspected food-related condition, the right route is an HCPC-registered dietitian, ideally Monash-trained if a low-FODMAP trial is on the table.

Ask a clinician, not a lab

The right test is the one that fits your history - and you may not need one.

Free to read, and independent: this page does not sell tests, supplements or diets.