The Mechanism of Food Allergies - Projects



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The Mechanism of Food Allergies

Japanese Chinese

Here, Dr. Yoichi Sakakihara, Director, Child Research Net, and pediatrician, responds to questions and concerns regarding children's physical well-being and health.

After I fed my six-month old daughter powdered milk formula for the first time, she had diarrhea for two weeks and when I took her to the hospital, I was told that she had a milk allergy. The diarrhea ended when we switched to a powdered milk using soybeans, but should she avoid dairy products from now on?

Food allergy refers to general illness that occurs when food becomes an allergen, causing an excessive immune reaction that is generally accompanied by such symptoms as diarrhea, vomiting, asthma, and a rash. Food allergies are mainly caused by milk, eggs, soybeans, nuts, and fish.

When bacteria enter the body, an immune reaction against protein in the bacteria is triggered, which prevents contraction of infectious disease. Proteins in food are broken down into amino acids and absorbed, but some proteins are absorbed without being broken down in the intestines. The above immune reactions occur in reaction to protein in food that remains undigested, and food allergy results as the body tries to expel it. An immune reaction due to IgE or cytokine produced by lymphocytes causes inflammation. If this inflammation occurs in the intestines, it results in diarrhea or vomiting, and if the inflammation occurs in the skin or the bronchial tubes, it results in itchiness or a rash. Inflammation in the bronchial tubes results in respiratory distress. In rare cases, inflammation may occur throughout the vascular system, expanding blood vessels and resulting in life-threatening conditions such as low blood pressure or shock.

Proteins are partially absorbed through the intestines into body, but due to suppressed immune reaction, most people do not develop food allergies. However, in infants, because the digestive system is still not fully developed, 5-6% of children have food allergies. This allergic reaction declines as they mature so that only 2% of adults are affected by food allergies. Unfortunately, however, it is still not clearly known why food allergies affect some people and not others.

In most cases, children will naturally outgrow a milk allergy, so although it is necessary to avoid dairy products in the child's diet for now, most children will eventually not show an allergic reaction to dairy products. However, some types of allergies are known to be lifelong, such as the food allergy to peanuts.

Note: The respondent of this Q&A series, Dr. Yoichi Sakakihara is a pediatrician practicing in Japan. Please remember to refer to the medical information or conditions of your own country, as the information or ideas contained in this article may not apply to your country.
Neither CRN nor Dr. Sakakihara shall be liable or responsible to any person or entity for any loss or damage caused, or alleged to have been caused, directly or indirectly by the information or ideas contained, suggested, or referenced in these responses.