Food allergy testing is not all it’s cracked up to be. In fact, there are some important aspects regarding foods you should avoid that food allergy testing does not assess. Let’s discuss what these are so that you can find the best diet for you.
Should You Perform Food Allergy Testing
Dr. Michael Ruscio: Hey, everyone. This is Dr. Ruscio. Let’s discuss if food allergy testing is worthwhile. In case you’re new to the issue, food allergy testing is typically done via blood. And it can help you determine if there are foods that you should be avoiding in your diet. And so of course, this theoretically has a lot of appeal.
And I’d like to play you an audience question that wants essentially to know more information about this. So let me play this question really quickly.
“Hi, Dr. Ruscio. I’ve been a big fan of your podcast for awhile and really like your monthly clinician emails and your overall perspective on functional medicine. I’ve been listening for awhile. And I can’t remember hearing you talk about food sensitivity testing. Do you think that there is any testing out there that is reliable or has valuable clinical use?
I prefer my patients to do more of an elimination-style diet like paleo, low FODMAP, AIP. But I’ll occasionally use a Cyrex array 3 for those that are unwilling to try giving up gluten for a few weeks to see if it would benefit them.
Say I get a patient that has an array 3 come back positive. They give up gluten for a month and don’t notice a change in their symptoms. Now, what do I tell them? Could it be impacting them even though they aren’t showing it through their symptoms? Do they need to give it up for a longer timeframe? Should they feel free to add it back in? Have you done a review of the literature on this or found food sensitivity testing to be clinically useful at all? I would love to hear your thoughts on the matter. Thanks so much!”
Okay. So great question. And that is admittedly an old question, meaning that it’s been sitting in our queue for a little while. So I apologize that it took me this long to get to this question. And I have spoken about this quite a bit between then and now.
But there are a few important things for us all to be aware of in regards to food sensitivity or food allergy testing. And I’m using the term loosely. But there are technically differences between labeling something as a food allergy, a food intolerance, or a food sensitivity. I’m just going to use it as a broad term, meaning that you should not eat a given food.
And I think it’s important to approach this question and ask, “What is the purpose of the testing?” And the purpose of the testing is to feel better. And by helping you to determine what foods to eat and not eat, you can potentially use the tool of food allergy testing to feel better. Does the food allergy testing deliver in this regard? In my opinion, it does not. And I’m going to outline that here with a couple comments and a couple thoughts.
Now, to the question of, “Have I done a comprehensive review of the literature on this?” I have not done a comprehensive review of the literature on this. But I do follow this literature. And there have been a handful of studies done. And we do have data showing.
And the best data that looks at this would take two groups of patients and would compare your traditional elimination/reintroduction diet where you cut out suspect foods and then bring them in one by one to determine what foods work for you and what foods don’t work for you. If you have a negative reaction proximal to a reintroduction of a food, that indicates that it doesn’t work well for you.
So in this case, gluten. Let’s say you take out gluten. Your joint pain goes away. In this case, she mentions someone with RA or rheumatoid arthritis. Joint pain goes away upon gluten withdrawal. Someone brings gluten back in. And their joint pain comes back. That would tell you that gluten is a problem for you.
So these studies have looked at this type of approach—elimination/reintroduction diet—against a food-allergy-testing-guided diet. And what you see is that, yes, the data does show that you may be able to more quickly determine what foods are problematic for you if you use food allergy testing. There is some data that does show that.
However, the most commonly found foods on these food allergy tests are ones that are outlined and covered in your food elimination diets. So there is some evidence suggestive that the testing may help you get there more quickly.
But when you factor in that oftentimes this testing is not covered by insurance and you’re looking at least a few hundred dollars, in some cases, several hundred, even to $1000 of cost, I certainly don’t think that it’s worth it. So that’s one.
Now, there’s more behind why I advise against food allergy testing. And that’s because food allergy testing only tells you a small fraction of the reasons behind why a food may or may not be a good idea for you. And when we look at other things like your carbohydrate tolerance, some people are carb sensitive, meaning they can’t eat a moderate to high amount of carbs. So they may not do well with more than about 150 to 175 grams of carbohydrate per day for metabolic reasons. So we don’t get an assessment of that on food allergy testing.
We also don’t get an assessment of how certain foods jive with your gut bacteria. And this is where someone would not have any inkling, any information as to whether or not they should eat a low FODMAP diet or not. And FODMAPs, for people who have digestive issues, can be very problematic. And this is not assessed at all on a food allergy test. Things like histamine can also be problematic for some people. Not assessed on the food allergy test.
So because of all this, I don’t look at testing as a helpful tool.
Now, there were a couple other questions within that question. And those were, essentially, if someone has been off gluten for three weeks and their joint pain hasn’t improved or they just haven’t improved at all, should they stay off gluten?
And in my opinion, no. Someone should have at least an initial sense of a response after a few weeks on a given diet. Now, there is some evidence that suggests that if someone has true, diagnosed celiac disease, it may take them longer to realize the full improvement. But it’s my strong suspicion that, even someone with celiac—and celiac is known to have, again, this longer time to realize the full improvement—even someone with celiac should be able to notice an improvement within a few weeks.
So if you’re at the three-week mark and you’ve noticed nothing, then gluten is likely not the problem. Or there may be another problem occurring in conjunction with gluten.
And so the way I would navigate this is have someone try a diet for about a two to three week period. And then move them to the next diet. And this is something that I outline in my book, Healthy Gut, Healthy You—how to go through a number of different diets in a stepwise fashion so that you can determine what foods you should eat and what foods you shouldn’t eat.
And essentially, the general principle here is we can start with something like a paleo diet. And then you may want to go to a more restrictive diet that also excludes gluten, like an autoimmune paleo diet or something like a low FODMAP diet which also excludes gluten. So gluten will probably be kept out of the equation for a number of weeks, maybe six to nine weeks total as you try to run these number of dietary experiments to determine what a person’s dietary tolerance is.
But it’s important to note that if someone does not notice any kind of improvement after cutting something like gluten out of their diet and after going through other dietary trials that may suss out foods co-occurring along with a gluten intolerance which was masking their ability to improve from a gluten elimination—if someone hasn’t improved after all of this, then either the foods are not a problem. Or there’s something else occurring, like potentially a bacterial overgrowth or a fungal overgrowth in the gut that is causing a problem with their symptoms.
And so what you have to do is drive toward helping someone get to a point where they have an improvement in their symptoms. And then you reintroduce foods. And whatever foods are problematic, they don’t eat them. And whatever foods are causing reactions, they avoid those.
Gluten is definitely one of the more problematic foods. But it’s not an issue for everyone. And it’s not something that has to be avoided strictly by all people, in my opinion. And remember, we talked about a study recently that looked at over 12,000 patients and found that over 90% of patients had a discernible reaction to gluten within 24 hours after ingestion.
So I don’t necessarily buy the party opinion that you need to be off gluten for months. And you may be eating it. And it may be fueling damage that you won’t feel for months or years. I’m open if the right data is presented. But I don’t think it’s that hard to figure this out fortunately, thankfully!
Thankfully, you don’t have to go on this restrictive diet for months and months and months and months to determine if a diet is working for you. If you’re practical and pragmatic, you can figure this stuff out in a fairly short period of time. But remember, there is also more to the equation sometimes than diet.
And again, my book, Healthy Gut, Healthy You, I think is a fantastic resource for this—I am biased—because it walks you through different diets quickly and then onto other therapies if diet doesn’t help you. It tries to get the person healthy and then moves them swiftly to a reintroduction so as to have the broadest diet possible in the long term.
So food allergy testing, there is some evidence to show benefit. The benefit is slight when compared to using a traditional elimination diet. And it does not really help you determine other factors that are important when trying to determine what someone’s best diet is.
And so for all those reasons, I do not recommend food allergy testing. I recommend these practical, mini experiments that can be done in two to three week increments to help someone determine what they should and should not eat. And if that does not work, look to a deeper root problem occurring in the gut.
So hopefully, that answers your question. And hopefully, this information helps you get healthy and get back to your life. Thanks!
What do you think? I would like to hear your thoughts or experience with this.
Dr. Ruscio is your leading functional and integrative doctor specializing in gut related disorders such as SIBO, leaky gut, Celiac, IBS and in thyroid disorders such as hypothyroid and hyperthyroid. For more information on how to become a patient, please contact our office. Serving the San Francisco bay area and distance patients via phone and Skype.