Once the idea had been floated that antibiotics might have something to do with obesity, academics started looking into it. They faced the challenge of corralling vastly dissimilar data sets into coherence and usable order.
Always, parameters need to be drawn, and boundaries observed. A team might start out with what looks like a lavishly sufficient number of subjects, but then reject half of them because their 5-year-old weights had been recorded by parents rather than professionals. Often, scientists begin with bright hopes, but have to abandon a hypothesis because there is simply not enough of the right kind of information to do anything with.
In 2012, news appeared of a longitudinal birth cohort study designed to “examine the associations of antibiotic exposures during the first 2 years of life and the development of body mass over the first 7 years of life.” They had the records of more than 11,000 children to work with, and landed squarely on intestinal colonization, or rather the interference with it by the administration of antibiotics, or by bottle feeding. Their report said,
Exposure to antibiotics during the first 6 months of life is associated with consistent increases in body mass from 10 to 38 months. Exposures later in infancy (6–14 months, 15–23 months) are not consistently associated with increased body mass.
A 2014 study added to the knowledge:
Using electronic health record data from 64,000 children, our research team identified an exposure-response association between the number of antibiotic treatment episodes during the first 2 years of life and development of obesity in later childhood, an effect that was most pronounced for broad-spectrum antibiotics.
That is another obstacle to designing good studies. There might be several thousand more potential subjects of the right age and other qualifications, but they took a different type or class of antibiotic. That would make an interesting study too, but it might not be the one on the table at the moment.
The United Kingdom’s National Health Service generates an awesome amount of data. A 2016 research team was concerned that antibiotics had been used for decades to promote weight gain in animals sold for human consumption. They set up a retrospective cohort study of the records of more than 20,000 children, aka “a population-representative dataset of >10 million individuals” and concluded,
Administration of 3 or more courses of antibiotics before children reach an age of 2 years is associated with an increased risk of early childhood obesity.
In the illustration at the top of the page, the map on the left represents obesity rates, while the map on the right represents antibiotic prescriptions. They come from the Centers for Disease Control by way of Frontiers in Pharmacology.
Your responses and feedback are welcome!
Source: “Infant antibiotic exposures and early-life body mass,” Nature.com, 08/21/12
Source: “Antibiotics, infections, and childhood obesity,” NIH.com, 11/01/16
Source: “Administration of Antibiotics to Children Before Age 2 Years Increases Risk for Childhood Obesity,” GastroJournal.org, July 2016
Image by Centers for Disease Control
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