San Mateo native Tom Brady is preparing for yet another Super Bowl. (Keith Allison/Flickr)

Cell turnover keeps athletes like Tom Brady healthy despite bacteria-ridden mouth guard

Watch Tom Brady’s mouth guard. In and out of his mouth, covered in football sweat and dirt. Hanging in or out of his helmet. And where else has it been? Common places that football players stash their mouth guards between plays are on the facemask, in socks, on the bench, inside skullcaps, held in the hand. Not surprisingly, studies reveal that mouth guards are typically covered in all kinds of bacteria, fungi, and yeasts associated with disease and infection. 

So, why doesn’t Brady get sick?

In essence, it’s because the microbiome, the organisms that live on that mouth guard, are actually changing with each football field, each helmet, and each insertion, So too are the immune system and the genetic makeup of Tom Brady.

It turns out that we are not mostly human. Of the 10 trillion microorganisms that make up the human microbiome, only one in 10 is identified as a human cell. What’s more, only a fraction of our 9 trillion non-human organisms has even been clearly identified as bacteria, virus or prions, or any other living organisms that we understand. The rest are organisms that we have yet to understand.

Let me explain. We’ve known about bacteria since the 1600s, finally making the link between germs and disease in the 1860s and 70s. The first virus was discovered in 1892, while the first prion (a protein that causes progressive neurodegenerative conditions) wasn’t identified until the 1960s. These discoveries have been enormously helpful in medicine. However, the majority of  the DNA in your nose and in your gut codes for organisms we have not yet identified, so-called “biological dark matter.” This large amount of unknown genetic coding and “organisms” make up most of what we consider us.

Not only that, the ecosystem of the human body is constantly invaded and the immune system responds to known and unknown new invaders with varying strength and effectiveness. While a small portion of the response may be preprogrammed by your genetic makeup, the reality is that there are too many new and unknown organisms. Fortunately, instead, we have a response system that both modifies itself by recording each new invader (memory cells) and modifies our genes so that they can produce a range of proteins and other molecules to defend ourselves in the future.

On top of that, the average lifespan of cells in our body is estimated to be 4,000 seconds. So, the Tom Brady you see at the beginning of the Super Bowl is not the Tom Brady raising the trophy or mourning the loss.

Brady doesn’t usually get sick, despite the presence of all kinds of nasty things in his mouth guard, because of the flexibility of his response system and the natural turnover of the human cells in the setting of an otherwise healthy body.  You can avoid getting sick too by maintaining a vigorously healthy body to defend against the blitzing invaders.

Dr. Kevin R. Stone is an orthopedic surgeon at The Stone Clinic and chairman of the Stone Research Foundation in San Francisco. He is a guest columnist.

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