Shay n Lucy

What About the Link Between Antibiotics and Childhood Obesity?

People with a cause like to hook it up with childhood obesity. Breastfeeding is good for both mother and child. But it doesn’t magically prevent childhood obesity – no matter how many times advocates try to suggest it does. Likewise, overusing antibiotics is a huge problem – mainly because it leads to huge problems with superbugs. There’s also an association between children receiving antibiotics and childhood obesity. However, three new papers in JAMA Network Open make it pretty clear. This association is mostly a distraction.

It’s a distraction for people who want to understand the major causes of obesity. And it’s a distraction from the real reasons for reducing antibiotic overuse.

A Big Study to Find a Small Correlation

The first of these three papers is a study of 6,853 children in New Zealand. They followed these children from birth to age four, paying close attention to antibiotic use, height, and weight. They did find an correlation between antibiotic use and BMI scores. But it was modest. Even in the group that received more than nine prescriptions for an antibiotic, the difference in BMI z-scores was only eight percent.

So maybe antibiotics are a factor. We can’t really tell because these are observational studies. Even so, nothing in this data suggests they’re a big factor.

Digging Deeper on Siblings and Twins

The second paper was also observational, and it was even bigger. These researchers followed more than 150,000 children in New Zealand. They also found a dose-dependent correlation between receiving antibiotics and obesity risk. It was modest, just like the correlation in the first study.

However, this study is different because they looked further into data on siblings and twins in this study. When they looked at siblings and twins with different outcomes, the correlation disappeared. Thus, said the authors, “these discordant results likely reflect unmeasured confounding factors.”


In the third and final of these papers, we find good perspective. Meghan Azad and Arthur Owora write:

From a public health perspective, antibiotic stewardship is an urgent priority, regardless of its potential role in obesity prevention. It remains unclear whether antibiotics causally influence obesity development in humans and whether particular antibiotic types or time windows of exposure are especially detrimental. These nuances are important to understand because, although the associations appear to be modest, they could be meaningful at the population level.

In other words, the link between antibiotics and obesity deserves further study. It may be one of many small factors that are adding up to a big effect on obesity prevalence. Regardless, we have better reasons to be concerned about antibiotic misuse. And those reasons are all about  the threat of antibiotic resistance.

Click here, here, and here for these three papers.

Shay n Lucy, photograph © Amanda Tipton / flickr

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January 23, 2020