How Do Food Sensitivity Assays Work?

Food sensitivities/allergies are in the public spotlight now more than ever –with approximately 5% of adults and 8% of children worldwide being affected by them.

Anyone that suspects that themselves or their child are suffering from a food sensitivity can be eager to learn what foods they are sensitive to, and how to avoid an adverse reaction. However, not all food sensitivity assays/tests give results that are fully relevant to all food sensitivities.

Multi channel pipette loading biological samples in microplate for test in the laboratory. Image Credit: angellodeco / Shutterstock
Multi channel pipette loading biological samples in microplate for test in the laboratory. Image Credit: angellodeco / Shutterstock

Different Types of Food Sensitivity Assays

Screening for food sensitivities has become increasingly popular. People who are looking to have tests done for certain food sensitivities sometimes seek the help of Holistic care providers. They are then given a ‘food sensitivity blood-test’ kit. The blood is then exposed to a panel of individual food and food components – with the degree of IgG (immunoglobulin G antibody) or IgG4 (immunoglobulin G subclass 4) binding to each of the panel food items being observed by enzyme or fluorescence-linked immunosorbent assays.

This method of screening, however, can be misleading. Usually, after the blood is screened, a list of foods to ‘avoid’ is sent back to the patient, with the foods that had the most IgG/4 binding being at the top. The list of foods a patient receives, however, goes drastically against what is so far scientifically understood about food allergies – as some foods on this list include “cheddar cheese”, or “cottage cheese”. Both products contain cow’s milk, which has casein and β-lactoglobulin, which are the main allergenic components of cow’s milk. Therefore, if the list were to be scientifically accurate, it would mention to avoid “cow’s milk” or “dairy”, rather than specific cow-milk products. This is a problem seen throughout this type of food sensitivity assay, as they are not testing for specific allergens – rather, just different specific foods.

Allergists and immunologists, however, use different food sensitivity assays to support clinical diagnosis. IgE (immunoglobulin E) is observed, rather than IgG or IgG4. In the IgE screenings, different types of immunoassays, such as the Radio Allegro Sorbent test or high-capacity solid-phase tests are used, as they both have the appropriate specificity and sensitivity to detect IgE in human serum.

A full screening ‘food panel’ is not used when observing IgE binding, with individual allergens and suspected allergens being tested instead. A full food sensitivity assay includes a good medical history, oral food challenges, prick-tests, and physical examinations – as well as the selected IgE level tests. This then gives a comprehensive answer to a small selection of tested common allergens, rather than a large range of specific food types. This method is compliant with current scientific knowledge on food sensitivities and is therefore a lot more accurate than the IgG/4 assays.

Anyone that suspects that themselves or their child are suffering from a food sensitivity is advised to seek medical guidance from a doctor, allergist, or immunologist. Doing this will ensure that any final information/medical advice is as accurate as possible, which can then be used by both yourself and your doctor to put together an action plan for avoiding and/or treating any adverse reactions to certain foods in the future.

Further Reading

Last Updated: Aug 23, 2018

Written by

Phoebe Hinton-Sheley

Phoebe Hinton-Sheley is currently studying for a Bachelor of Science (B.Sc.) degree in Microbiology at the University of Wolverhampton.

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