Food Sensitivity Testing: How accurate is it?

A few weeks ago, another Naturopathic Doctor posted an interesting experiment in a professional Facebook group. He had drawn his own blood and sent in 2 identical blood samples in for food sensitivity testing. He had used his own name for one and a false name for the other, but the blood was the same. The results were shocking… almost no overlap between the results in terms of which foods he was sensitive to, and the levels of antibodies found. So, are food sensitivity tests a scam?

To better answer this question, we should discuss what a food sensitivity test is and how they work. To simplify a complicated concept, food sensitivity is when a person has created IgG antibodies against a food protein. Food allergies are mediated by IgE antibodies and result in the typical hives, itching, and possibly difficulty breathing and anaphylaxis. IgG antibodies mediate a more chronic inflammation. IgG is the antibody made to store a long-term immunity such as from virus’ like Mono or the Chickenpox. These antibodies are long term, but over time can reduce to a very small amount which is why certain vaccines need to be given again to keep the levels high enough to prevent disease. When IgG is made to food, the levels remain higher since we are exposed to that food more often than we would be exposed to let’s say Chickenpox. This creates systemic inflammation as the immune system is recruited to fight the intruding “banana protein” every time you eat one. Long term chronic inflammation can result in a disordered immune system eventually contributing to diseases such as autoimmune disorders, arthritis, asthma, eczema etc. In order to reduce the inflammation, the food you’ve created antibodies to, should be eliminated until the liver can clear the antibodies from your system. If “leaky gut” is involved, heal the gut lining so no more food proteins enter the blood stream and stir up the immune system again.

This is where food sensitivity testing comes in. The labs that offer this testing claim that they are measuring the levels of antibodies in the blood sample to however many foods they are testing for. Many test for between 30-100 different foods and some test for over 200. In theory, this can be very useful, so you know what foods to eliminate and can reduce that inflammation. In practice, its not so clear cut.

Example Food Sensitivity Test (ALCAT) (This is an old one, but they look pretty similar today.)

In my experience, food sensitivity testing seems about 50% accurate. Sometimes I’ll have a client look at the list and say things like “I don’t even like mushrooms” and mushroom antibodies are high. I’ll have tests come back negative for foods that obviously bother the client. “I get joint pain whenever I eat dairy, and it didn’t come back positive on the test.” I also get clients that the results make total sense and eliminating the foods sets them on the road to recovery. This leads me back to the puzzling results that my colleague in the first paragraph discovered. Obviously, one guy’s results do not mean much in terms of a scientific method, but it is interesting. It could be that the particular lab he used is not high quality. It could indicate that the antibodies were not evenly distributed in blood samples, which would be very weird or as he surmised… the method of testing just isn’t that accurate, even if the idea of food sensitivity tests make sense. Since I have used several different labs with the same trends, I tend to agree with him. It is also certainly possible that a food that is bothering a client is doing so not because they have antibodies to it, but for some other reason such as lactose intolerance, cross reactivity, or FODMAP sensitivity. This means the lab might report a negative result to a food that is causing symptoms.

So where does that leave me now with clients? Reality is that there are around ten foods which are the top offenders. Any nutritionist or physician will tell you that elimination is the most accurate way to test food sensitivity. If you eliminate a food and the symptoms go away, then bring it back and the symptoms come back…. You are sensitive to that food for some reason, no matter what a lab report says. I always offer food sensitivity testing as an option, but with all the information on possibly accuracy issues and of course the cost. So, we do an elimination diet with reintroduction for the top 10 foods first and then go from there. Occasionally, I’ll have a client that eliminating the top ten foods does not help and then I’ll run a food sensitivity test (usually the a full panel including possibly IgE and IgA antibodies to make sure we don’t miss something weird). Sure enough, something strange like “blueberries” come up positive and then eliminating them was helpful, but I can count those people on one hand. At the end of the day, food sensitivity testing is a useful tool in the right circumstances, but I don’t think it’s accurate enough to be relied on fully. If a client is interested, I’m happy to help them run one, but its not my first recommendation.