By: Mark Tran

The use of antibiotics in young children may alter the natural populations of gut microbes in a way that leaves them predisposed to weight gain and asthma in later childhood, according to new research.

The study of 236 children aged between two and seven, with a median age of five, backs earlier research on mice and children indicating the negative consequences of early antibiotic use. Antibiotics are the most commonly used drugs in childhood populations of western countries.

Researchers at the university of Helsinki said the use of antibiotics is associated with a long-lasting shift in microbiota – clusters of bacteria from different regions of the body – and metabolism. 

Humans and other animals are home to vast populations of microbes that live on the skin and in the gut. Humans carry around 100 trillion bacteria – meaning microbes outnumber human cells by 10 to one. But rather than causing us harm, studies suggest that a healthy “microbiome” is crucial for our wellbeing.

“Among the children who received macrolides (a class of antibiotic) in early life, we find a positive correlation between overall lifetime antibiotic use and body mass index (BMI), as well as an increased risk of asthma, suggesting that macrolide use may alter the microbiota in infants in a way that predisposes to antibiotic-associated weight gain and asthma in later childhood,” said the study published in Nature Communications.

Previous research on mice suggested that antibiotics are not directly to blame for weight gain later in life. Instead, the problem arose when antibiotics wiped out some types of gut bacteria but allowed hardier ones to thrive. This change in composition of the microbiome had a long-term impact on metabolism that persisted even when the population of gut microbes had returned to normal several weeks later.

The Finnish researchers said their results confirm corresponding patterns in human children:

“The children with heavy early-life use of antibiotics but no antibiotics for at least two years before sample donation had a microbiota similar with those with low lifetime antibiotic use. Nevertheless, early life use of macrolides predisposed to overweight and asthma. These results suggest that even transient microbiome disturbance in early life may have long-term effects on the metabolic and immunological health of the child.”

As for asthma, the researchers said their study suggested that macrolide alters the microbiota in a way that disrupts the healthy immune development system. This is in line with with previous large international studies that have found an association between asthma and early use of antibiotics.

“Our results confirm and extend previous results from mouse experiments and indicate that macrolide use may have undesired effects on the developing microbiota of children, which may compromise the development of a healthy immune system and metabolism.”

Originally Published: The Guardian