Illness may appear in adulthood because of antibiotic resistance we develop when doctors prescribe us antibiotics as newborns and infants, researchers say.

The antibiotics may alter infant gut bacteria, which are tied to everything from allergies and obesity to infectious diseases, according to a new study published in the scientific journal Cell Host & Microbe.

Researchers from the University of Minnesota found that antibiotics eliminated bacteria in the gut that enabled the growth of allergen-fighting immune cells. Antibiotics were also found to alter critical gut microbiota that determine our vulnerability to a number of infectious diseases.

“Over the past year we synthesized hundreds of studies and found evidence of strong correlations between antibiotic use, changes in gut bacteria, and disease in adulthood,” said the study’s lead author Dr. Dan Knights.

Antibiotics remain the most prevalent drug prescribed to children, accounting for approximately a quarter of all childhood medications. However, around 30% of prescriptions are deemed unnecessary.

“We think these findings help develop a roadmap for future research to determine the health consequences of antibiotic use and for recommendations for prescribing them,” Knights added.

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