By the age of two, one in ten children are considered obese. Considering that obesity early in life puts one at greater risk of obesity later in life, childhood obesity is something to pay attention to. Now, a new study published in JAMA Pediatrics claims to have found an association between the use especially the use of multiple courses of treatment with antibiotics before the age of two, and an increased risk of obesity by the age of five. However, despite the breathless headlines provoked by this apparent link, the methods used by the researchers need to be examined a little more closely.
Researchers from the University of Pennsylvania and the Johns Hopkins-Bloomberg School of Public Health looked at the medical records of 64,500 infants and children who were followed from birth until the age of five. The majority of those children had been prescribed two courses of antibiotics before age two. Researchers found that completing four or more courses of antibiotics before the age of two was associated with a ten-percent increased risk of obesity by the age of five. And being prescribed broad-spectrum antibiotics antibiotics that kill several types of bacteria was independently associated with an increased risk of obesity as well.
According to Dr. Charles Bailey of the Children s Hospital of Philadelphia, this last association points to a bigger problem. Broad-spectrum antibiotics are meant to be used only if the narrow-spectrum kind do not work. And in practice, many doctors may prescribe antibiotics in cases where they are not needed at all, oftentimes at the request of a parent.
In trying to explain their findings, researchers turned to studies done on mice, in which mice fed antibiotics demonstrate changes in the gut that ultimately affect digestion, calories and energy extraction. However, as we ve said many times before, mice are not little men. Additionally, in examining almost 65,000 medical records with rates of obesity at one in ten children, by trying to correlate many potential inputs with also-large possible outcomes, researchers may well have been able to use the numbers to find any association they wanted; in other words, with so many data-points, the chances of finding some statistically-significant association was very high, by chance alone. Thus, we have here a prime example of data-dredging.
Furthermore, according to ACSH advisor Dr. David Shlaes, one cannot draw a parallel between feeding antibiotics to animals and weight gain in children. He says, I think that the basic idea behind the research was that since antibiotics cause faster growth in animals why wouldn t the same be true for people? But unlike animals, kids don t get low doses of antibiotics in their food every day.
The study also had limitations, most importantly that the researchers did not look at weight or exercise regimens or other lifestyle factors in the children that may have contributed to obesity.
ACSH s Ariel Savransky says, This research is clearly missing this crucial lifestyle factor that may contribute to obesity in children. But it also makes a point that these lifestyle factors are extremely important in the early years of child s life and parents and doctors should pay close attention to young children and their eating habits. However, what the researchers failed to point out: children who need antibiotics four or more times before the age of two may also have some other underlying condition(s) which may predispose them to obesity and this is something else worth investigating further. And of course, this study should not be used to avoid prescribing antibiotics to children when necessary.