Should toddlers try peanuts? Is your ulcer a bug’s fault? The ‘flip-flopping’ of health advice

In the early 2000s, the advice for parents was clear: Don’t feed babies and toddlers foods containing peanuts. It might increase the child’s risk of developing a severe allergy to the ground nut.

By the late 2010s, newer research pushed pediatricians to advise the opposite. Parents should introduce peanut products before children turn a year old because it might keep youngsters from developing a peanut allergy. Now, a recent study that analyzed medical records of tens of thousands of children validated the introduce-peanuts-early guidance.

This flip-flopping health advice drives many conscientious parents crazy. If they follow advice that later proves wrong, they may feel guilty or distrustful. If they ignore medical guidelines, friends or relatives may question their judgment. The country’s polarized political environment, in which Americans’ party affiliation tends to influence whom they trust for health information, only exacerbates the situation.

As frustrating as it may be, the evolving guidance about peanuts is exactly how science is supposed to work. A question arises—why are peanut allergies increasing among children in Western countries?—and scientists tackle it. Answering that question could take many researchers many years of effort.

They need to confirm whether the trend is real, rather than an artifact of a new diagnostic tool. They may compare diets of babies in places where food allergies are increasing against places where food allergy rates are stable. They will test multiple hypotheses, trying to understand exactly why the incidence is rising. It is detailed, painstaking work.

With a potentially life-threatening condition, like a severe food allergy, clinicians want to offer diet or treatment guidelines promptly. Sometimes, the advice isn’t effective, but the research continues and guidance evolves to incorporate new findings.

For much of the 20th century, for example, physicians believed firmly that stress, diet and smoking caused peptic ulcers. In the 1980s, Australian researchers discovered that a corkscrew-shaped bacterium, Helicobacter pylori, could cause the ulcers. (One scientist even helped validate the hypothesis by drinking a solution laced with the bacteria and making himself sick.)

It took several years to convince skeptical peers, but antibiotics ultimately became the standard treatment for ulcer patients who harbored the bacteria.

The recent peanut allergy study, published in the journal Pediatrics, is compelling. It found that the incidence of peanut allergies declined after doctors began recommending that parents introduce peanut products early. A commentary published in the same journal offered some caveats, but the introduce-early advice stands for now.

Reliable medical advice is based on multiple, carefully designed studies, involving large numbers of people, that point in the same direction. Advice can and should change over time, but only after a systematic process that incorporates new information and expert reviews. The process is not perfect, but it’s far more trustworthy than a trending video on TikTok.

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