What are the symptoms of food allergy and intolerance?

Food allergy is a reaction directly mediated by the immune system. It has a quick onset and severe symptoms. Food intolerance is mostly related to insufficient digestive enzymes and abnormal metabolic pathways. It has a slow onset and deep-seated symptoms. Many people have repeated stomach upsets and rashes and cannot find the root cause. In all likelihood, these two are at work.

I met a 3-year-old patient a while ago. His parents took him to a relative's house to play, and he secretly took a sip of pure milk. Within 10 minutes, the area around his mouth swelled into a small sausage, and his body was covered with red wheals. He was still gasping for breath. When he was sent to the emergency department, Parents were scared to tears. This is the most typical acute IgE-mediated food allergy. In mild cases, it may just be itchy skin, numb mouth, and rash. In severe cases, it may cause laryngeal edema, difficulty breathing, or even anaphylactic shock, which can be really fatal. In addition to milk, foods such as mango, peanuts, seafood, and nuts are all highly allergenic. Many people will have reactions within half an hour after eating them. You can basically find the trigger by just thinking about them.

Compared with this kind of menacing allergy, the symptoms of food intolerance are much more "cunning". There was an office girl who came to me for consultation before. Her mouth closed and her abdomen was bloated after meals for more than six months in a row. Each time, the symptoms were like an inflated balloon, even the jeans she usually wore. I couldn't get it right, and after a bunch of tests, nothing was wrong. Finally, I kept a food diary for two weeks and found out that as long as I drank milk tea with creamer that day, I would definitely have symptoms the next day, and it would be gone soon after I stopped. This is a typical case of non-dairy creamer plus lactose intolerance. This type of delayed reaction often occurs several hours or even 1-2 days after eating. It may be bloating, diarrhea, constipation, or inexplicable headaches, fatigue, repeated acne and eczema on the skin. Few people will immediately think that something went wrong with what they ate a few days ago.

I would also like to mention here that there is a lot of controversy in the academic world about the food intolerance tested for food that is very popular on the Internet. There is a group of scholars who believe that the positive result detected by this test is just the immune memory of the body's exposure to such food. It does not mean that you are intolerant to it. If you blindly follow the reported taboos for several years, you will be prone to nutritional deficiencies. I generally suggest that you don’t rush to get a test worth thousands of dollars, but keep a food diary for two weeks first. If you feel the same discomfort after eating a certain type of food three or four times in a row, it’s not too late to consider avoiding it.

If you really experience numbness, swelling, or wheezing in your mouth immediately after eating something, don’t force it, take anti-allergy medicine immediately or go to the emergency room. You really can’t be careless about allergies.