The journal Pediatrics published a study on Monday showing that peanut allergies in the United States have dropped by more than 40 percent in recent years.

Scientists believe that’s largely thanks to changes in federal guidelines a decade ago that encouraged parents to introduce foods containing peanuts to babies in their first year of life.

This trend is worth celebrating on public health grounds. It also represents a triumph of science over hysteria — a cautionary tale about the harm that public health advocacy can cause when experts fall prey to groupthink.

America’s fraught relationship with peanuts began in the 1990s, when the media started to sensationalize tragic stories of children experiencing severe allergic reactions after being exposed to the legume, sometimes resulting in death.

Those accounts produced a snowball effect: More researchers started to study peanut allergies using self-reported incidents from parents, which reinforced a perception of a growing “epidemic” that needed to be addressed.

In 2000, the American Academy of Pediatrics issued a recommendation that children who were at “high risk” of developing an allergy should avoid peanuts entirely until they turn 3.

Because it was unclear how to determine which kids were at high risk, many well-meaning pediatricians and parents adopted broad anti-peanut philosophies for toddlers.

The result: Children increasingly failed to train their immune systems to recognize peanut proteins as not dangerous. So instead of preventing peanut allergies, they proliferated.

From 2005 to 2014, the number of emergency department visits for peanut reactions tripled. By 2019, according to one study, 1 in 18 American children had an allergy to peanuts.

This has had a profound impact on the country. Many schools — egged on by overly protective parents — began aggressively policing peanut-containing products, with some even segregating kids at different tables during lunchtime based on allergies.

Universities, too, have sought to create allergy-free zones. So have airlines, which largely eliminated peanuts on flights.

Perhaps the most striking aspect of this public health disaster is how long it took for the medical establishment to change course. Researchers began recognizing the downside of peanut avoidance within years of the AAP’s guidance in 2000, especially since other countries that did not adopt it had far lower rates of peanut allergies.

Yet it took until 2015 for federal public health experts to officially acknowledge what had been increasingly obvious for years.

Even then, it took the publication of a landmark paper that definitively showed feeding peanuts to babies dramatically reduces their chances of developing an allergy when they grow up.

All of this underscores the risk of overreaction in the realm of public health.

Pediatricians, of course, did not intend to exacerbate peanut allergies, but by straying from scientific evidence, they made things worse.

With trust in health agencies continuing to slide downward, these are mistakes the medical field cannot afford to keep making.

— The Washington Post