AUTHOR: Dr. Jason Bush
Here’s a riddle: Name the only collection that features items inherited from your mother, your dog, and your grocery store. Give up? It’s your microbiome.
Of course, your microbiome includes microbes from hundreds – if not thousands – of different places, reflecting the history of our interactions with the world that surrounds us. And this collection is fragile, with certain bacteria being more vulnerable to loss than others due to antibiotics or other factors. A recent study of people in Tanzania following a traditional hunter-gatherer lifestyle even showed that the microbiome can be subject to the seasonal change in food availability.
So how do each of the sources listed above contribute to the collection in your intestines?
Maternal influence is crucial in seeding the infant gut microbiome and typically occurs via two interactions. The first is the process of giving birth, where the previously sterile newborn passes through the birth canal and out into the world. Here, the vaginal microbiome plays the central role in contributing to the gut microbiome. Famed microbiome researcher Dr. Rob Knight believed so deeply in the importance of vaginal microbiome transfer that he actually facilitated this process using a swab following the C-section delivery of his child.
The other major maternal source is the skin, with most of this transfer coming during breast feeding. Breast feeding plays an important supporting role for the gut microbiome, supplying indigestible human milk oligosaccharide prebiotics to feed the nascent microbiome.
Studies have shown that people with pets, including dogs and cats, have significant overlap in the types of bacteria that make up their microbiome. In other words, you inherit microbes from your pets. Presumably, this occurs as your pets clean by licking themselves from head to toe, and beyond, and you pet, cuddle, or kiss your furry friends. If you follow any of this contact by literally grabbing a bite to eat, you are giving these microbes an excellent opportunity to colonize your digestive tract. It’s not pretty, but it’s not necessarily a bad thing: Microbiome diversity is an important factor in preventing dysbiosis and traveler’s diarrhea.
Or pickles, salami, or any food containing living probiotics. Fermented foods like these contain Lactobacilli probiotics, which tend to be transient inhabitants of the gut microbiome. But the health benefits of Lactobacilli have been well-documented, so consuming these foods can help enrich the diversity of your microbiome. Just remember that you need to regularly be consuming these foods in significant amounts if you want to keep their associated probiotics as part of your intestinal collection.
Hopefully these points outline just how easily the gut microbiome can be colonized by microbes from our environment. By the same token, it’s just as easy for harmful bacteria from the toilet handle or tainted foods to get a foothold. Fortunately, a healthy gut microbiome containing colonist from the healthy sources listed above will help keep the unhealthy bugs at bay.