Q: Why are peanut allergies so much more prevalent than they used to be? — Via email

A: It is estimated that 1 percent of children in the United States have peanut allergies.

Symptoms range from a rash, eye watering or congestion to a more serious reaction known as anaphylaxis that may include a swollen throat, trouble breathing, a sudden drop in blood pressure, and even death. These reactions can occur anytime during the first four hours after exposure, and may occur within the first 20 minutes.

At-risk adults and grown children with peanut allergies must carry self-administered injections of epinephrine so they can give themselves a shot right away. They must then go to the nearest emergency room.

Parents, teachers and other caregivers of young at-risk children must always carry at least two doses of injectable epinephrine and know how to administer it. Even a tiny amount of peanut can set off a reaction in some children.

Peanuts are used in many processed foods. Other foods from a factory that uses peanuts may also be contaminated. In the United States, food labels should specify whether a food contains peanuts or peanut products, and whether it has been processed in a factory where peanuts may be present.


Peanut allergies are a major public health concern. But the answer to your question remains elusive.

The general consensus is that peanut allergies in the United States have increased during the past 15 years. But it is not clear whether the rate continues to rise. Some evidence shows that it may have begun to level off.

We also don’t know whether the rise in peanut allergies is a worldwide phenomenon. If we could pinpoint when and where peanut allergies increase, we might have some clues about why.

Peanut allergies are far less common in Asia. Why? Most Westerners eat dry-roasted peanuts. Asians mostly eat fried or boiled peanuts. Processing changes the nature of peanut proteins that cause sensitization and allergies. Peanuts are more allergenic when dry-roasted than when fried or boiled.

An allergic reaction to a food requires an initial exposure early in life that sensitizes the immune system, leading to an allergic reaction with subsequent exposures. Early-in-life exposure to dry-roasted peanuts or processed foods that contain them may explain the higher rate of sensitization and subsequent allergies in Westerners.

Until we do have the research to answer your question, it will remain unclear what we can do to prevent peanut allergies.


Questions or comments should be addressed to Dr. T. Berry Brazelton and Dr. Joshua Sparrow, care of The New York Times Syndicate, 620 Eighth Ave., 5th Floor, New York, NY 10018. Questions may also be sent by email to:


— New York Times Syndicate


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