Food Sensitivity Testing

Food Sensitivity Testing

In this Extra Credit article I’m going to focus on blood testing for food allergens/sensitivities. What they are…and what they are not. Unlike the other installments of this blog, I do not have a scientific article to review, however, this topic keeps coming up and is really gaining steam in the mainstream so I thought it would be good to address here. We probably all know someone that has had this testing done or is considering it. Sometimes they come home with results that indicate an ‘allergy’ to nearly everything they are currently eating!! What does this mean? Stop eating? Unfortunately, these tests are being used without a full understanding of their substantial limitations.

What is Food Sensitivity Testing?

There are several different permutations of blood testing for food sensitivities, however, we can boil down the mechanisms pretty easily.

One method: ‘Cytotoxic Testing’

The cells that mediate a food ‘sensitivity/allergy’ are ‘leukocytes’, more commonly known as white blood cells. By various mechanisms, these cells are your army against enemies, both foreign and domestic! So, the hope is that in taking some of your blood and exposing those white blood cells to lots of different types of foods, they will see changes in those cells that indicate a sensitivity or an allergy.

Here is what happens in a nutshell. A drop of your blood is placed into a little receptacle or well that contains an extract of a food that is being tested. Depending on the test, there can be hundreds of little wells, each containing a different food extract. Your blood is observed over the course of specific time intervals (every so many minutes) to see if there are changes in your white blood cells that would indicate a sensitivity or allergy.

Unfortunately, there just isn’t any solid data that this type of testing tells us much of anything that is clinically useful in determining what one should and should not eat.

Another method: ‘Antibody Testing’ (this is the predominant method gaining current popularity)

One of the mechanisms by which white blood cells protect us is by producing proteins called antibodies. When I taught A&P, I would liken these to bullets that are sent out to destroy very specific targets. Theoretically, if your body is producing antibodies to food, this is a sensitivity or allergy and can be known through testing. The good news is that this is an absolutely plausible mechanism! The not-so-good news is that there are many other factors in play. For instance, for results to be valid, they have to be reproducible. This has been a huge problem for antibody testing as there have been many tests done that involve sending a patient’s sample (blood, saliva) to several different labs and sometimes even sending a split sample to the same lab! This practice has produced some wildly differing results, well outside acceptable tolerances.

An additional problem involves the substances being tested. Sometimes, there are chemical constituents or excipients (NOT the food itself) that can, themselves, cause an antibody reaction from white blood cells. Another food-related issue is whether they expose the patient’s sample to raw or cooked or some other preparation. This matters! Heat and agitation can destroy proteins that might otherwise be reactive. For instance, your blood may produce antibodies in response to raw eggs. However, once the egg is cooked and the offending proteins have been denatured, you may not react.

And finally, there is this idea that ‘familiarity breeds contempt’ within the body and especially in regards to the immune system! In short, this means that if you eat the exact same foods, every…single….day, the body is more likely to begin creating antibodies to those foods. This is why I always tell my patients to rotate their food. Seasonal rotation of vegetables and fruit is not only easy, but ensures that you are getting the most nutrient-dense, best tasting offerings.

Is There Any Benefit to This Testing?

From a clinical standpoint, the primary benefit can be seen when people get results back that look a little like they are ‘allergic to everything’. And it’s certainly the things they are eating all the time! When people come to me with results like this, it’s a great indicator that they are struggling with intestinal permeability (aka ‘leaky gut’). This means that the barrier function in the intestine is compromised and undigested food proteins are getting across the intestinal wall and have access to the immune system. The immune cells then recognize them as enemy (non-self) proteins and begin to generate antibodies in response. What this result does not mean is that the individual must remove those foods completely from their diet forever. What they need to do is work on restoring the barrier function to keep foreign proteins out. This is most efficiently done under the supervision of a Functional Nutritionist, like myself.

Keeping all of the previous points in mind, it is absolutely conceivable that people do, indeed have sensitivities that show up on these tests. The problem is in both reproducibility and with the state of the food proteins being tested or foreign proteins that show up in the samples. So we may even get some results that are theoretically valid, however, there is really no way to know. And certainly, if people are feeling bad and have specific symptoms or groups of symptoms, there is often a food trigger. Therefore, if the patient takes a food sensitivity test and everything that he or she is eating shows up on it…they will necessarily improve once the dietary offenders are removed. However, there are circumstances of false positives and false negatives that can give people a false sense of what they are able to eat. For instance, someone that is very sensitive to dairy but has not eaten dairy for the last six months or a year, will not have antibodies show up on these tests because they simply aren’t there. They may think that dairy is fine for them, but really it’s simply a function of non-exposure.

What to do Instead?

The clinical elimination diet is the unparalleled gold standard to ferret out which foods may be causing problems. It is not easy. However, working with a Nutritionist that specializes in these elimination/provocation diets can make all the difference in your ability to comply. Based on your symptoms, medical history and goals, you can be given a diet to follow that rules out the likely offenders but may not require removal of all possible offenders.

It’s quite elegant in its simplicity, however I will state again, it’s not easy. When offending foods are removed, the antibodies and immune components that were created to fight those foods, need to be deactivated. The half lives (the time it takes for half of them to degrade and become inactive) of these specific antibodies being tested for varies but the longest is around 22 days. This means that by day 22 of an elimination diet, you can know that at least half of all the antibodies that are causing problems are gone! And you should be experiencing marked improvements in your health and symptoms. The length of an elimination is at least 30 days, but the exact length is determined by your symptom abatement. If, after 30 or 35 days, you are feeling much better then you can reliably move on to the ‘challenge’ or provocation (or reintroduction) phase. This is arguably the most important phase of the whole process and must be done very carefully. Again the supervision of a practitioner is highly advisable.

A Personalized Solution

I have put many, many patients on therapeutic elimination diets and no two were ever identical. It needs to be highly individualized to maximize both efficacy and compliance. However, it can still be difficult and require a high degree of ‘hand-holding’ to be successful. To accommodate that, we have created an 8-week class where participants will work with me to create their own, unique, elimination diet based on symptoms, history and goals and will complete the diet during the course of this class. The reintroduction phase will also be closely monitored to yield the very best results.

If you have been told you should try an elimination diet by your physician or primary care team but you would like some clinical support while doing it, we would love to have you join us for this class. If you are facing complex, chronic health conditions and you are unsatisfied with the effectiveness of your current regimen, we would love to have you in this class, as well. For more information on this class or our other services, please visit us at