The Antibiotic Dot

In the past, Childhood Obesity News posted a general overview of the research about antibiotics, babies and obesity, and took a closer look at a five-way link between antibiotics, premature births, ototoxicity (or hearing loss), obesity, and epigenetics (the passing along of somatic liabilities to descendants). Well, let’s call that instead a six-way network of links, because, as it turns out, the microbiome adds itself to the mix and complicates the game of connect-the-dots.

We may wish out colonies of interior bugs would chill out once in a while, but no. Everything about us is their business. One characteristic of the microbiome is stubbornness.

Michael Pollan charmingly explains:

Your microbial community seems to stabilize by age 3, by which time most of the various niches in the gut ecosystem are occupied. That doesn’t mean it can’t change after that; it can, but not as readily… Just like any other mature ecosystem, the one in our gut tends to resist invasion by newcomers.

However, the microbiome of a child is vulnerable to change from antibiotics, of which the average beneficiary of western civilization is treated at least a dozen times before the age of 18. Even if it were possible to keep a child healthy without any doctor visits, the antibiotic residue ingested through water, milk, and meat is unavoidable.

It should come as no surprise that the unintended consequences are serious. The gut fauna are bacteria, after all, and bacteria are what antibiotics are designed to kill. Even when we take a course of antibiotics for the most legitimate reason, there is always collateral damage. Our good bugs, our allies and comrades-at-arms, die by the millions as a result of “friendly fire.”

We have catalogued extensively the characteristics and habits of the bacterium Helicobacter pylori, which lives in the human stomach. Researcher Martin Blaser discovered that H. pylori aids in appetite regulation, by controlling the level of the “hunger hormone” ghrelin.

Strangely, this bug used to be much more prevalent, and it may be coincidence, but when H. pylori started to disappear from the American gut, the obesity epidemic really got underway. In the words of Scientific American writer Claudia Wallis:

Blaser […] notes that antibiotic use varies greatly from state to state in the U.S., as does the prevalence of obesity, and intriguingly, the two maps line up — with both rates highest in parts of the South.

Researchers from Johns Hopkins found that antibiotic use can permanently change the microbiota, affecting they ways in which food is broken down, and even increasing the absorbed calories. They wrote “Antibiotic Use and Childhood Body Mass Index Trajectory,” which shows that children who receive antibiotics tend to gain weight in a very noticeable way, when compared to other kids.

Worse, there is what they term a “compounding effect.” In other words, weight gain accelerates with age. The study leader, Dr. Brian S. Schwartz, told a reporter:

Our data suggest that every time we give an antibiotic to kids they gain weight faster over time… [O]ur finding that the effects are cumulative raises the possibility that these effects continue and are compounded into adulthood.

Just to round things out, here is a tidbit of information about zero-calorie artificial sweeteners, reported by Jason Best:

When researchers used antibiotics to wipe out the gut bacteria of mice, it completely reversed the effects of the artificial sweeteners on the mice’s glucose metabolism. Likewise, when scientists took the gut bacteria from glucose-intolerant mice and transferred it to mice that had had their gut bacteria eradicated, the recipients became glucose intolerant.

Glucose tolerance is not something you want to mess around with. Altogether, there seems to be more and more reason to employ caution in dealing with the microbiome.

Your responses and feedback are welcome!

Source: “Some of My Best Friends Are Germs,”, 05/15/13
Source: “How Gut Bacteria Help Make Us Fat and Thin,”, 06/01/14
Source: “Children Who Take Antibiotics Gain Weight Faster Than Kids Who Don’t,”, 10/21/15
Source: “Drinking Diet Soda and Not Losing Weight? Blame Your Gut Bacteria,”, 09/18/14
Photo credit: Andres Rueda via BY

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About Dr. Robert A. Pretlow

Dr. Robert A. Pretlow is a pediatrician and childhood obesity specialist. He has been researching and spreading awareness on the childhood obesity epidemic in the US for more than a decade.
You can contact Dr. Pretlow at:


Dr. Pretlow’s invited presentation at the American Society of Animal Science 2020 Conference
What’s Causing Obesity in Companion Animals and What Can We Do About It

Dr. Pretlow’s invited presentation at the World Obesity Federation 2019 Conference:
Food/Eating Addiction and the Displacement Mechanism

Dr. Pretlow’s Multi-Center Clinical Trial Kick-off Speech 2018:
Obesity: Tackling the Root Cause

Dr. Pretlow’s 2017 Workshop on
Treatment of Obesity Using the Addiction Model

Dr. Pretlow’s invited presentation for
TEC and UNC 2016

Dr. Pretlow’s invited presentation at the 2015 Obesity Summit in London, UK.

Dr. Pretlow’s invited keynote at the 2014 European Childhood Obesity Group Congress in Salzburg, Austria.

Dr. Pretlow’s presentation at the 2013 European Congress on Obesity in Liverpool, UK.

Dr. Pretlow’s presentation at the 2011 International Conference on Childhood Obesity in Lisbon, Portugal.

Dr. Pretlow’s presentation at the 2010 Uniting Against Childhood Obesity Conference in Houston, TX.

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