What factors affect food allergies?

Judging from the cases that I have been exposed to in the clinical allergy department for more than ten years, food allergy is never caused by one factor alone, but is the result of a combination of innate genetics, early exposure, immune status, intestinal flora, food processing methods and even the surrounding environment. There is rarely an absolute case of "being born allergic to a certain food", and most are triggered by the combination of multiple triggers.

Of course, there are also susceptibility to many allergies that are inherited from the mother. If both parents have allergic diseases, whether it is rhinitis, asthma or food allergy, the probability of a child developing food allergies can be more than 40%. I have met three generations of a family who are allergic to mangoes. Grandma’s mouth swelled after eating mango, father’s skin itched when he touched mango, and his grandson’s throat edema immediately after taking a bite of mango puree and he was sent to the emergency room. The susceptibility brought about by this kind of inheritance makes it easier than ordinary people to react to various allergens.

In addition to the natural allergy, there is more room for discussion on the impact of exposure habits during growth on allergies. Nowadays, people often say that "too clean can cause allergies". In fact, there has been controversy in the industry. Previous studies have shown that children who are exposed to soil and pets more during childhood are less allergic. This is because microorganisms in the environment can help train the immune system and will not attack harmless food proteins. However, there are also studies from the opposing side that show that frequent exposure to soil and pets during childhood is unhygienic. Raw food and repeated gastrointestinal infections will damage the intestinal mucosal barrier and increase the risk of food allergies. To put it bluntly, it is not "the dirtier, the better", but contact with "good microorganisms". For example, if you have a furry pet at home, don't wipe the table and hands with disinfectant every day. Normal cleaning is enough, and there is no need to pursue a sterile environment. There was a little patient before. His parents were afraid that he would get sick. They had to steam sterilize tableware since he was a child and wipe his hands with disinfectant wipes until they were shiny. As a result, he became severely allergic to eggs for the first time when he ate eggs at the age of 3. On the contrary, another child in the same community who crawled on the ground every day and had two dogs at home was not allergic to any complementary food.

In addition, your current physical state and the way you process the food itself may suddenly break the original tolerance balance. A 28-year-old girl who was treated two months ago was fine after eating shrimp for more than 20 years. She stayed up late last week to catch up on a project for three days. After work, she went to eat crayfish with her friends after get off work. After eating two, her mouth became swollen and she couldn't breathe. She was sent to the emergency room for an IgE test and it was discovered that she was indeed allergic to shrimp. She was confused, saying that she was fine no matter how much she ate before. This was caused by typical immune fluctuations. Originally, her body was tolerant to shrimp allergens, but staying up late continuously disrupted the immune balance. The immune system treated the originally harmless shrimp protein as an enemy, thus inducing allergies. There are also food processing methods that many people ignore. I often tell patients that if you are allergic to eating raw apples, you might as well try steamed apples. Many people are allergic to the polyphenols or proteases in raw fruits. After high-temperature cooking, these allergens are destroyed, and they will be fine if they eat them. There was a little patient before who was allergic to raw peaches and even touched the peach hairs. However, eating canned yellow peaches did not cause any problems. This is the reason.

Another influencing factor that many people don’t notice is the status of the intestinal flora. Many people actually “create” food allergies by themselves. For example, they take laxative enzymes or take antibiotics casually, which kills all the beneficial bacteria in the intestines. The intestinal barrier leaks, and the food proteins that were originally tolerated leak into the blood, which can easily induce allergies. There was a young man who took Internet celebrity enzymes for a month and suddenly became allergic to the milk he had drank for more than ten years. He stopped the enzymes to nourish his intestines for more than half a year before slowly drinking milk again.