Self-Care Challenge (Day 296): Learning About the Human Gut Microbiome

Cyntia Lair teaching a class at Bastyr on the microbiome

As a dietitian, I’m well aware that I’m interested in things most people aren’t. For the past sixteen years, patients and clients (and even strangers) have shared some, well, um, personal things about their digestive health with me.

It comes with the territory.

One of my college professors likened our digestive tract to “a giant donut hole,” and when you really think about it, it’s pretty accurate. Substances enter our giant donut hole, a lot of processes and exchanges take place, and then substances come out the other end of our giant donut hole.

Except these processes and exchanges are really, really, really complex.

And I happen to find all of this very fascinating.

So, as my self-care practice for the day, I attended a workshop on the Human Gut Microbiome at Bastyr University in Kenmore, WA.

What exactly is the human gut microbiome?

The human gut contains trillions of microbial cells, commonly referred to as microbiata, and each of these microbial cells contains unique genes that have an impact on the human body. The microbiata produce metabolic signals, many of which we don’t yet fully understand.

For perspective, there are more bacteria in the human body than there have ever been people living on this earth, and the average person has 2 to 4 pounds of gut bacteria living in their colon at any given time.

What’s perhaps even more fascinating, though, is that the human gut microbiome contains more genes than the human body itself–with the microbiome carrying 1,000,000 genes compared to the human genome’s mere 23,000 genes.

Further proof that humans are indeed an integral part of nature, not separate from it.

Can the microbiome be changed?

One of the most surprising things I learned is that it’s believed that our microbiata profile is “set” by age 2 to 3, and while the numbers of bacteria may change over time, the profile remains unchanged. So while we may do our best to introduce new strains over the course of our lifetime, it may not produce any real change.

This brought me back to my years as a nutrition consultant in long-term care facilities, where antibiotic use was quite common. A standard protocol to preserve gut flora during treatment was to introduce cultured dairy or a prescribed probiotic. I have to admit, it was an empirical treatment at best, and not one that I ever truly felt was effective. But like many treatments in institutionalized care settings, doing something is always viewed as better than doing nothing, no matter how much it costs.

But like most researchers who study this relatively young science, I’m left with so many more questions than answers. Even the research that’s been conducted to date is limited at best.

As one of this workshop’s professors admitted, “What grows in the lab might not grow in the gut.”

More questions to ponder…

Are there certain combinations of bacteria that do not “play well together,” and is this perhaps why there is so much geographical diversity?

How is our culture’s fascination with cleanses and supplements (and their excipients) impacting our microbiata?

Since it it believed that our microbiata profile is established by age two to three, is attempting to introduce new bacteria even worthwhile?

Do manufactured, single strain probiotics change the microbiata profile in infants and toddlers, or is their profile dependent on environmental factors only? (Also, how does the fact that 30% of probiotic supplements fall short of amounts listed on their label play out?)

Since the short-chained fatty acids (SCFA) produced by microbiata alter the pH of the gut, how does that shift affect human health?

If there is indeed bidirectional communication between the brain and the gut, how does that affect human cognition?

How does soil exposure impact the development of the microbiata in children and adults?

How do fermented foods compare to manufactured supplements in terms of impact on the microbiata (and microbiome)?

I also find it intriguing that a large number of a mother’s bacteria “bloom” just before birth, and many physicians who deliver babies by Cesarean have started to proactively “swab” newborns with substances they would have come in contact with had they been born vaginally.

The human body is indeed a mysterious machine. I don’t think we’ll be running out of questions any time soon.

If you’re curious about what’s growing inside your gut, you can send a fecal sample (along with $99) to the American Gut project. (Keep in mind, your results will only include bacteria found in your sample, and not what lives within the colon’s biofilm.)

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