Most common food allergies

There are currently eight categories of allergens that have been identified globally and account for more than 90% of all food allergy cases, namely milk, eggs, peanuts, tree nuts (cashews, walnuts, almonds, etc.), wheat, soybeans, fish, and crustacean aquatic products (shrimp, crab, shellfish, etc.). This is also the core list of allergens that are mandatory for labeling on food packaging in various countries.

Last week, I accompanied a friend with allergies to the hospital for a review. The mother sitting next to me in the waiting area was holding a 13-month-old baby. The corners of his mouth were red and he had a small rash. He was in tears. It was because the grandma didn't know that the baby was allergic and fed her a mouthful of ordinary formula milk. Cow's milk protein allergy is the most common food allergy among infants and young children. The previous consensus among academic circles was that babies with allergies should strictly avoid cow's milk and drink only deeply hydrolyzed or amino acid milk powder until they are at least 3 years old before trying to gradually add it. However, in the past two years, the European Pediatric Allergy Society has conducted many studies and suggested that as long as children have not experienced severe immediate reactions such as laryngeal edema and anaphylactic shock, gradual exposure to ordinary cow's milk protein in small doses starting from the age of 6 months under the supervision of a doctor can shorten the time for establishing immune tolerance, and return to a normal diet half a year to a year earlier than babies who completely avoid food. The two views are still being discussed. Clinically, the choice of plan will generally be based on the child's allergy level, and there is no absolute right or wrong.

You may not believe it, but I met a colleague during team building two years ago. Within three minutes of taking a bite of an egg tart, his lips swelled up and his speech was slurred. After being rushed to the emergency room, I found out that he was allergic to egg white. He has been afraid to touch large eggs since he was a child. Individual differences in egg allergy are very large. Some people cannot touch whole eggs. Some people are only allergic to raw egg whites and are completely fine if they eat fully cooked eggs. Some people were allergic when they were children and got better after puberty. There is no unified rule.

I used to watch American TV series and always wondered why children were not allowed to bring peanut butter sandwiches to school. Later, when I volunteered for popular science, I found out that the incidence of peanut allergy in European and American people is three times higher than in China. In severe cases, even a slight touch can cause laryngeal edema and suffocation. It is one of the food allergies with the highest risk of death. Interestingly, in the past, many parents in China were afraid that their children would be allergic and would not touch nuts at all when they were young. This has led to an increasing rate of nut allergy detection in school-age children. Now the mainstream recommendation of domestic allergy departments has become that after adding complementary foods for 6 months, you can try a small amount of nuts ground into fine powder. As long as there is no reaction after eating them for the first time, adding small amounts regularly can reduce the probability of allergies. This is exactly the opposite of the early saying that "it is safer to avoid eating early".

Many people feel bloated after drinking soy milk and feel uncomfortable after eating noodles. They always say that they are allergic to soy or wheat, but in fact, they are most likely not allergic. A true food allergy is an immune response mediated by IgE. It usually occurs within half an hour after exposure, ranging from rash and numbness in the mouth to difficulty breathing and shock. For example, the flatulence after drinking soy milk is mostly due to the oligosaccharides in soybeans that have not been digested. If you feel uncomfortable eating noodles, if it is accompanied by long-term diarrhea and weight loss, you should be alert to celiac disease induced by gluten. This is an autoimmune disease and is not the same as ordinary wheat allergies. Don’t be confused.

As for the most commonly heard seafood allergy, it depends on the situation: some people are only allergic to ray-finned fish such as hairtail and salmon, and they are fine eating shrimps and crabs.； Some people are just the opposite and are only allergic to tropomyosin from crustacean fish, so eating fish is perfectly fine. There are also people who have numbness in the mouth and rashes after eating stale seafood. In fact, it is poisoning caused by the histamine in the seafood that has not been decomposed completely. It is not an allergy. You will be fine if you eat fresh seafood next time, and you don’t need to completely avoid it.

In the two years I have been doing science popularization, I have seen too many people guessing about allergies and not daring to eat this or that, and in the end they are lacking in nutrients. If you really suspect that you have a food allergy, don't search for symptoms on the Internet to find out. Go to a regular hospital to get blood drawn to check for specific IgE. If necessary, do a food challenge test, which is more accurate than anything else. After all, eating is a major event in life, so I lost so much fun of delicious food for no reason, thank you.