What’s the deal with the infant microbiome?

The human microbiome is one of the hottest topic in medical research today, and with good reason.

This collection of trillions of microscopic inhabitants–bacteria, viruses, and fungi—cover nearly every interior and exterior surface of the human body, and many scientists now believe that these unseen co-passengers, far from being incidental hangers-on, are instead actively cultivated by our bodies and play a critical role in our immune and metabolic health.

Over the last decade, studies have linked the composition of our microbiomes the to a panoply of modern ailments: obesity, asthma, allergies, acne, C difficile induced diarrhea, and autoimmune diseases like Crohn’s and Type 1 Diabetes.

Our microbiome may matter most in early infancy.

Newborns first encounter many of the bacteria, viruses, and fungi that will colonize their bodies during delivery. During the first few months of life, complex interactions with these microbes are believed to help train our baby’s rapidly developing immune systems, helping them learn to distinguish self from other, and friend or harmless allergen from foe.

As just one sign of how important these microbes may be for our babies: The third largest component of human breastmilk–complex carbohydrates known as oligosaccharides–are designed not to feed our babies (who cannot digest them), but to pass through our babies stomachs to their intestines, where they feed beneficial bacteria. These bacteria have evolved special genes to break down human milk oligosaccharides, and their presence is believed critical for calibrating our babies’ immune systems.

(I talk more about the fascinating relationship between breastmilk and bacteria here.)

We desperately need a better understanding how microbes affect our baby’s health, especially since we currently disrupt the mom-to-baby microbial transfer–with C-sections and antibiotics given during labor–in over half of all U.S. births.

The world of the infant microbiome is hardly the only yawning chasm in our knowledge. The sum of what we know is far less than the sum of what we don’t. Just for example, we do not even know whether the cells of these microbes outnumber the number of cells in the average human’s body by a factor of 10 or 100. In other words, we don’t know whether they add a piddling 0.2 lbs or a whopping 2 lbs. to our body weight. That’s a whole hot smokin’ pile of uncertainty.

Efforts at the National Institutes are underway to provide a “map” of the normal human microbiome and its relationship to human health, as Jane E. Brody reports in the New York Times:

Under the auspices of the National Institutes of Health, a large team of scientists is now engaged in creating a “normal” microbiological road map for the following tissues: gastrointestinal tract, oral cavity, skin, airways, urogenital tract, blood and eye. The effort, called the Human Microbiome Project, takes advantage of new technology that can rapidly analyze large samples of genetic material, making it possible to identify the organisms present in these tissues.

Unfortunately, creating microbiome road map is almost surely a decades-long effort.

In the meantime, new parents can take several steps that research suggests are safe, and potentially beneficial, to give their baby’s microbiome’s a boost, as I describe in my latest post for Bloomlife, 8 Ways to Boost Your Baby’s Microbiome. Please check it out, and let me know what you think!

Author: Amy Kiefer

As a former research scientist and proud mama of three little munchkins, I love digging into the research on all things baby-related and sharing it with my readers.

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