Allergen Testing Food Mix

Mixing common foods before routine food allergen testing (serum specific IgE testing, skin prick testing) will not interfere with the test results at all. Only mixing suspected allergenic foods before the oral food challenge test must be strictly avoided. In addition, antihistamines cannot be taken within 48 hours before all allergen testing. It has nothing to do with how the food is mixed.

Last time, I accompanied my best friend to take her 3-year-old son, Xiao Maodou, for an allergen test. Before going out, the child grabbed a piece of rice cake mixed with chopped mango and gnawed half of it while the adults were not paying attention. My best friend only realized it when she registered at the hospital. She was so anxious that her eyes were red. She said that if she just ate mango and mixed it with rice, the test would be inaccurate. She waited in line for an expert for half a month. When I went in, the doctor laughed and said that even if you ate pancakes, fruit and rice pudding porridge mixed with more than a dozen ingredients in the morning, you would be fine, as long as you didn't take anti-allergic drugs like loratadine.

If you think about it, serum-specific IgE checks the long-term presence of antibodies in your blood that correspond to allergens. It does not check the newly digested food residue in your stomach. What you eat affects the antibody concentration, which requires repeated exposure for days or even weeks. Mixing and matching in one meal will not make any waves at all. Not to mention skin pricking, which involves applying purified allergenic solution on the surface of the skin to see the reaction. It has nothing to do with what is in your stomach.

Of course, I also know that many people have experienced "inaccurate results after eating something before taking the test", mostly due to the now controversial bioresonance allergen test. Many private institutions will instruct you in advance not to eat complex food, touch metal, or even drink hot water 24 hours before the test, saying that it will interfere with the results. However, from the perspective of the mainstream allergology community, there is currently insufficient evidence-based medical evidence to support the accuracy of bioresonance testing. The so-called "food mixing affects the results" is essentially that the stability of the testing method itself is poor. The testing results may be different at another time or even with another machine. It really has little to do with whether you eat mixed food or not. Of course, I won’t kill this type of test with a stick. Some patients do report that the results are consistent with their actual allergies. You can choose according to your needs, but you don’t need to take the “no mixed food” requirement too seriously.

However, not all tests have no requirements for mixed food. Currently, the only one that requires strict control of food mixing is the oral food challenge test, which is the gold standard for allergen testing. For example, a real incident that our department encountered last year was that a parent brought his child for a milk challenge test. He was afraid that the child would be hungry, so he secretly stuffed half a piece of bread mixed with peanut butter. As a result, the child broke out in hives half an hour after eating. No one could tell whether it was the milk or the peanuts. Not only was the test on the same day in vain, but he also had to make an appointment a month later, which was very frustrating. When doing a provocation test, eat whatever the doctor tells you to eat. Don't add random things on your own, let alone mix several suspected allergens together, otherwise it will really be a waste of money and suffering.

Another scene that people often overlook is that when keeping a food diary at home to check for allergens, try not to mix foods in an exaggerated way. I once met a patient who ate crayfish, mango, nuts, milk and spicy hot pot for a meal. After eating, he developed wheals on his body. He asked me what he was allergic to. How could I know? If you want to investigate by yourself, try to keep the ingredients for a meal as simple as possible. When adding new ingredients, add them separately, and observe if there is no reaction for three days before touching anything else. Otherwise, it will be too mixed, and if there is a problem, you will not be able to find the culprit.

In fact, to put it bluntly, you don't need to be too anxious about "can you eat before the test?" You should just remember not to take anti-allergic drugs before going for a routine test. If you do a provocation test, the doctor will clearly explain the precautions to you in advance, and you will be fine if you follow them. I have seen too many people starve all morning to test for allergens, and then faint immediately after taking blood. It is really unnecessary.