Your microbiome: it's who you are

You may already know that about 90 percent of the cells on your body are not your own. They belong to the more than 100 trillion microorganisms—such as bacteria and fungi—that live in your gut, mouth, skin and everywhere else. Your gut alone contains about 40,000 species of bacteria. For every one of your own genes you have 100 genes from the microorganisms. It’s kind of a creepy idea, but in fact these microbes help you digest food, synthesize essential nutrients and vitamins, and prevent disease-causing pathogens from invading your body. Together, these organisms are called your microbiome and it is unique to you.

Your microbiome plays a critical role as a filter between the environment and our body’s own cells. Substances must first pass through layers of microbiota on the skin, gut, and airways at which point they may be sequestered, excluded, or metabolized before they enter our cells. At the same time, the microbiota are training our immune systems.

We pick up the critters that make up our microbiomes beginning at birth with our trip through the birth canal. From that point on, we are “seeded” with microorganisms through our continuing contact with our home environment. Apparently, our microbiomes becomes stabilized at about age three.

Recent advances in DNA sequencing has brought much of this information to light. Scientists are now looking at the ways in which our microbiota affect our health. Some have suggested that changes to our microbiomes over the last 75 years account for the rise in diseases such as diabetes, heart disease, asthma, autism, inflammatory bowel disease, obesity, and many more. Many—if not most—of these diseases were virtually unknown 75 years ago.

For example, a bacterium called Heliobacter pylori once occupied the stomach of nearly every person in the world, having been intertwined with our species for at least two hundred thousand years. Now it is found in just five percent of children born in the US. H. Pylori plays a role in regulating stomach acid and in quieting the inflammatory response. While it can cause ulcers, the near-eradication of this bacterium has now been shown to have a serious downside. Many Americans now suffer from acid reflux, and the rate of a certain type of esophageal cancer has soared. What’s more, researchers have found the lack of H. pylori to be implicated in the rise of asthma and allergies.

The heavy use of antibiotics may be the main culprit. Also, scientists believe that moving from dirty rural environments to clean urban environments also account for the change in our microbiomes. Because we are less exposed to microbes than in the past, our immune systems are not being challenged in the ways they once were.

There’s not a lot you can do to change your microbiome, although some efforts are being made in that regard. I’ll discuss this next week.

Next week: Messing with your microbiome.

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