Unintended changes in the early life microbiota and their health consequences

“Here's Fleming pretending to rediscover penicillin,” said Dr. Martin Blaser, as the mix of medical students and professionals chuckled at the black and white photo of Alexander Fleming flashed on the screen. “He’s being a good sport, posing for the camera.”

The group gathered for a talk about how modern plagues - obesity, asthma, bowel diseases, allergies - are fueled by the loss of ancestral microbes. According to the CDC, these microbes are naturally occurring bacteria in and on the body and they are greatly affected by the use of antibiotics.

“We are realizing that in addition to their benefits, antibiotics have costs - including increasing the risk for obesity, diabetes, etc.,” continued Blaser, the director of the Human Microbiome Program at New York University Langone Medical Center. “It means that doctors will need to use antibiotics more carefully, and people should not be demanding them - they are both good and bad.”

Over the last 20 years, Blaser has developed a hypothesis called, “the theory of disappearing microbiota.” Children inherit microbiota from their mothers but that has been affected in recent generations due to the use of antibiotics, whether they were born naturally or through c-section, and were breastfed. Those born naturally and were breastfed have more microbiomes than those that do not. But all of this is affected by antibiotics, especially if the child receives antibiotics before the age of three years old.

Through his research, Blaser learned that antibiotics use in the U.S. has gone up to five courses for every six people year after year. And by looking at the data, also saw that high usage of antibiotics, such as in the southern U.S., has higher rates of obesity compared to other areas, like the West Coast which has low antibiotics use and lower rates of obesity.

“A big issue is the over prescribing of antibiotics in the outpatient setting,” said Dr. Anne-Catrin Uhlemann, an infectious disease specialist in the College of Physicians and Surgeons at Columbia University. Uhlemann conducted a study on MRSA infections and found that most of the participants were prescribed antibiotics in the past six months, with 50 percent of the healthy patients saying they took antibiotics.The important thing to consider is that antibiotics are basically a reset button, continued Uhlemann. And this opens the way for harmful and antibiotic resistant bacteria to take hold and cause problems.

Aside from taking antibiotics, people can also ingest it through the food that they eat. Blaser discussed how antibiotics that are only used on farms, to increase the growth of cows and chickens, were found in Chinese school children. The antibiotics were ingested through food, milk, and even through drinking water (from the effluent farms discharged into rivers and oceans).  Here in the US, the FDA has rules limiting the use of antibiotics on farms and prescriptions have to come from veterinarians.

To find out how antibiotics affects weight gain and microbiota, Blaser and his team conducted experiments on mice. Through the many tests performed, the results were consistent - mice exposed to antibiotics gained fat easily and had lower microbiota numbers. As well as those mice that received antibiotics had a higher chance of diabetes, colitis and inflammatory bowel disease (IBD), among others.

So what does the future hold? According to Blaser, ”I think that we will be giving back precise organisms to children in the future, probably adults too. Either the organisms themselves - true probiotics - or chemicals that support their growth (called prebiotics). All of that is a new approach to precision medicine.”

This does not mean that people should now rush to groceries, pharmacies, and health food stores to buy a bottle of probiotic tablets. “By probiotics, I mean the future scientifically-tested and validated next generations of pre- and pro-biotics,” said Blaser.