Eight categories of allergic foods

Currently, there are eight categories of highly allergenic foods that are generally recognized by global food supervision and allergy circles, namely milk (mainly milk), eggs, crustaceans (shrimp, crab, lobster, etc.), fish, nuts, soybeans, wheat, and peanuts. The "General Principles for Labeling of Prepackaged Foods" implemented in my country in 2021 also clearly requires that if these eight types of ingredients and their products are used in processing, prompts must be marked in the ingredient list, in order to help people with allergies avoid pitfalls.

In the past two years, I have been sorting out allergy cases in the allergy department of a tertiary hospital for half a year, and I have seen too many mistakes: a child in elementary school secretly took a bite of a peanut butter cookie brought by his deskmate, and was sent to the emergency room with laryngeal edema on the spot.； An office worker had diarrhea for a week and thought it was gastroenteritis. It was finally found out that he was allergic to the wheat protein in the whole-wheat bread he eats every day. ； There is also an aunt who gets rash every time she eats cold dishes from outside. It took her a long time to figure out that it was the shrimp powder added to the cold dishes that makes her fresh. She is allergic to crustaceans.

Many people confuse milk allergy with lactose intolerance. In fact, they are completely different things: Allergy is when the immune system attacks the casein and whey proteins in milk. It can range from rashes and diarrhea to shortness of breath.； Lactose intolerance is a lack of the enzyme to digest lactose. Drinking milk will cause bloating and gas, which is not life-threatening. There is also a controversial point about milk allergy: some pediatricians believe that the protein of goat milk and camel milk has low homology with cow's milk, and children with mild allergies can try it. There is also a group of scholars who believe that as long as it is mammal milk, the probability of cross-allergy can reach more than 80%. People with severe allergies must not try it blindly. If they really want to change, they must first undergo an allergen test.

As common as milk allergy is egg allergy. Many people think that allergies are only caused by egg whites. In fact, the vitellin in egg yolks is also a common allergen, and many people don't know that half-boiled eggs are much more allergenic than fully cooked eggs. I met an aunt before who usually ate hard-boiled whole eggs without any problems. Her mouth swelled every time she ate toast brushed with egg wash on the street. In the end, she found out that the egg wash on the toast was only half-cooked and the allergenic protein was not completely denatured.

Let’s talk about crustaceans, which are the shrimps, crabs, and crayfish that we often eat. Don't think that you will be allergic only if you eat it. I have seen the chef get a rash on his arm when the shrimp juice splashed on his arm when he was cleaning up the shrimp. Nowadays, shrimp powder and crab paste sauce are particularly popular in pre-made dishes and takeaways to enhance the freshness. If you don’t see the shrimp when eating, you may have been infected. There was a young man who was allergic to braised chicken before. After a long investigation, he found that the store added shrimp powder to enhance the freshness. He didn’t know it at all.

As for fish allergies, there is really no saying that "deep-sea fish are less susceptible to allergies." Many studies have shown that the allergenic proteins in deep-sea fish are more stable and difficult to destroy even when cooked at high temperatures. Moreover, fish allergies vary greatly among individuals. Some people are allergic to all fish, while others are only allergic to freshwater fish such as grass carp and carp. There is nothing wrong with eating salmon and tuna. Don't listen to others who say "if you are allergic to fish, you should avoid touching all fish." It is more reliable to do a test yourself.

Nut allergy is currently underdiagnosed in China. Many people experience numbness in the mouth and itchy throat after eating almonds and walnuts. They always think that it is "heat" or "the nuts are not cooked well", and they never think that it is an allergy. And unlike milk and egg allergies, which many children will tolerate when they are six or seven years old, nut allergies are mostly lifelong. If it is found to be a nut allergy, it is best to pay more attention to it and don't taste nut products that you have never eaten before.

Then there are soybeans. Many people think that they are exposed to soybeans only by drinking soy milk and eating tofu. In fact, soy lecithin in daily snacks, soy sauce and bean paste used for cooking are all soy products. There is also a point that has been debated in the industry for a long time: most experts believe that after fermentation of soybeans, allergenic proteins have been degraded. Even people with soybean allergies can eat soy sauce and fermented bean curd normally. However, there are very few cases of severe allergies. Even a little soy sauce will cause a rash. This depends on the degree of personal allergy. There is no unified standard answer.

Wheat allergy has been mentioned more and more in recent years. Many people confuse it with "gluten intolerance" (also known as celiac disease). In fact, wheat allergy is an acute reaction of the immune system to the protein in wheat. Celiac disease is an autoimmune disease and is completely different. I have come across a particularly interesting case before: an elder brother who ran a marathon was fine eating noodles and steamed buns. But every time he ate bread after running a marathon, he would get rashes all over his body and be out of breath. He was finally diagnosed with "wheat-dependent exercise-induced allergy" - to put it bluntly, after eating wheat, he will be fine as long as he doesn't move. When he exercises strenuously, his immune system will react to wheat protein. Isn't it quite subversive?

Finally, let’s talk about peanuts. Many people think that peanuts are nuts. In fact, they are from the leguminous family. Peanut allergies have the highest fatality rate among all food allergies. A serious exposure may induce anaphylactic shock. Therefore, many schools in Europe and the United States simply ban students from bringing peanut products into school. There are now two completely different intervention ideas for peanut allergy: One is the more popular "early introduction", which says that adding a small amount of peanut butter to babies when adding complementary foods can reduce the probability of subsequent allergies. ； The other group believes that high-risk babies with a family history of allergies should wait until they are 3 years old before touching peanuts to avoid inducing severe allergies. Currently, both sides have research data to support them. You still have to listen to your doctor for specific choices.

In fact, there are now many studies calling for the addition of allergenic fruits such as mangoes, peaches, and kiwis to the highly allergenic list. However, the current global classification is still divided into eight categories. If you often have unexplained rashes, tight throats, or diarrhea, and you can't find the trigger, don't force yourself to do it, and don't blindly search yourself on the Internet to scare yourself. Go to the allergy department of the hospital to check for allergens, which is more effective than anything else.