Why many food Allergy and sensitivity tests aren’t reliable

Many food allergy and sensitivity tests marketed directly to the public—such as IgG blood panels and hair strand testing—are not supported by robust scientific evidence and are not recommended in UK clinical guidance for diagnosing food allergy or intolerance.

It's important for those with food concerns to understand the potential issues with purchasing an expensive and unproven test.

IgG blood tests

IgG testing measures immunoglobulin G antibodies, which indicate exposure to foods rather than an adverse immune response. UK and international professional bodies, including guidance referenced by NICE and allergy organisations, state that IgG testing has no proven role in the diagnosis of food allergy or intolerance. Positive results are common in healthy individuals and do not reliably correlate with symptoms.

These tests usually show foods you eat regularly, not foods that are causing a problem. A positive result doesn’t mean you’re intolerant.

Hair strand testing and other alternative methods

Hair strand testing and similar approaches (such as bioresonance, electrodermal testing, or applied kinesiology) have no established biological mechanism for identifying food allergy or intolerance. NICE and NHS-aligned communications have highlighted that these methods lack evidence of accuracy and should not be used for diagnosis.

Hair testing can’t tell us how your immune or digestive system reacts to food. There’s no reliable science behind it.

Potential risks of non-validated testing

Use of non-evidence-based tests may result in false positives, unnecessary food avoidance, increased anxiety, nutritional inadequacy, and delayed identification of underlying conditions. These risks are highlighted in UK clinical and consumer safety guidance.

These tests can lead people to cut out lots of foods they actually tolerate well, which can affect nutrition and quality of life.

Evidence-based UK approach

In line with NICE and NHS guidance, suspected food allergy should be assessed using a detailed clinical history and validated testing (such as IgE testing) where appropriate. Food intolerances are best identified through structured dietary assessment, symptom monitoring, and supervised elimination and reintroduction protocols.

The most reliable way to identify problem foods is by carefully looking at symptoms and how your body responds when foods are removed and reintroduced in a planned way.