A Primer on Gut Flora

Driving along a suburban road on the North side of Brisbane (Australia), a kangaroo bounds seemingly out of nowhere and hits the side of my car. Minor vehicle damage but the animal was clearly in pain and could not get up. After phoning 1300 Animal, the Vet arrived and gave us the sad prognosis. He did have some good news though, as he fished out a very-much-alive joey out of the nearly dead kangaroo’s pouch. He said: “Be sure to mix these in with his milk” as he handed me some of mum kangaroo’s droppings.

As we nursed joey with poop-imbued cow’s milk it grew and grew until the sad time came for release. Clearly, the Vet’s advice was founded upon his knowledge of joey’s inability to digest cow’s milk. It got me interested in aspects of microbiome inherited from the mother and matters of our own gut flora. This article gives overview to how we acquire the all-important gut flora.

It appears we humans can acquire our gut flora in at least 4 ways:

Physical transmission from our mothers.
Diet: E.g. Sauerkraut, Yakult-style probiotics, etc.
Recently discovered, genetic transmission.
Engraftment.

Acquisition from Our Mothers

Intergenerational handing down of microbiome occurs from great grandmothers and older, to mother and finally child by the process of passage through the birth canal. Then there is contact with the mother’s skin as well as breast milk delivering mouth microbes. As well transmission takes place from the mother’s placenta, uterus and vagina. Placental microbiota is discussed more fully by others in the know

Far from being a sterile environment (as thought), researchers found microbial presence in amniotic fluid and baby’s first stool. Although our gut microbiome is influenced by diet, gender, geography and ethnicity, our initial acquisition appears to be the most important.

Dietary Considerations

You can eat kimchi, sauerkraut and a host of other fermented products and improve your gut flora and thereby your overall health. However, if anti-biotics and other flora-destroying agents are on your menu, you will lose some of your precious microbiota.

One of the worst enemies of gut flora is air pollution. Inhaled particulate matter is quickly cleared from the lungs and finds its way into the intestinal tract altering susceptible microbiota. Smoking is in this class.

Microbiome Acquisition via DNA

Approximately 17 years ago the Genome Project delivered a complete sequencing of human DNA. This was a significant accomplishment for mankind. With that project now well in place, is it possible that some microbiota might be transmitted by parents to their off-spring DNA?

In a UK study of over 1000 twins, researchers set out to determine whether human genes are implicated in the transmission of microbiota. Whilst they sought to include environmental transmission in their study as well, they found about 12 microbes beneficial to health that were heritable via DNA..

Research is continuing at the National Institutes of Health’s Human Microbiome Project to map the genetic blueprints with microbiota variants. Early findings would indicate on strong evidence that microbial genes are linked to primal ancestors.

Engraftment

With the loss of gut flora throughout life’s exposures there is risk that some microbiota in a given person are irrecoverably extinct. Just like in the kangaroo and joey story, engraftment becomes a desirable intervention. Now the idea of swallowing someone else’s poop is highly unpalatable. A nasogastric tube or colonoscopy become more acceptable modalities.

The science of human microbiome is still in its infancy. Not all microbiota are catalogued and cross-referenced with disease and well-being. Then too, are fecal donor similarity requirements and certainty of microbiota survival in the recipient in the longer term.