👇 NEW THIS MONTH - Audio Recording 👇

Good morning, friends!

Have you ever heard of Terrain Theory and its relationship to health?

At its simplest, Terrain Theory asks us to think about more than the germ that makes us sick.

It asks us to think about the person that germ encounters.

For a long time, people have debated which matters more—the germ or the health of the person exposed to it.

But why does it have to be one or the other?

We aren't meant to live in a germ-free world. In fact, we couldn't.

Bacteria, viruses, fungi, and other tiny organisms are all around us. They also live on us and inside us. Many are harmless. Some actually help keep us healthy. And yes, some can make us sick.

The germ matters.

But so does the condition of the body it meets.

That's the part of Terrain Theory that interests me.

If two people are exposed to the same thing, why might one get sick while the other doesn't? Why might one barely notice it while the other spends a week in bed?

There are many reasons for that.

Our age and genetics matter. Our past exposures and immune defenses matter. How much of something we're exposed to can matter.

And our terrain matters.

We often think of our terrain as what's happening inside the body—our immune system, nutrition, gut health, microbiome, sleep, stress, blood sugar, and overall resilience.

But even our microbiome is bigger than we sometimes realize.

We hear a lot about the gut microbiome, but the gut isn't the only place microorganisms live. Different communities live in and on different parts of our bodies.

We are not sterile beings trying to keep the microbial world out.

We are part of the microbial world.

Which has me thinking about a much bigger question:

Do we understand just how big our terrain actually is?

Because our internal terrain exists within another terrain.

And another.

Fall is a whole-system transition

Think about everything that changes as summer becomes fall.

Daylight decreases. Temperatures and humidity shift. Plants prepare for dormancy. Leaves change and fall.

The natural world is transitioning.

And so are we.

We move indoors. Schedules change. Kids go back to school. Teachers return to classrooms. Activities start back up.

And suddenly hundreds of people who spent the summer living, traveling, playing, and interacting within completely different environments are spending their days together again.

Within a few weeks, we start hearing:

"Something is going around."

"Johnny brought something home from school."

"Everyone in the class has it."

And eventually...

"Well, it's flu season."

But what if there's a bigger story happening?

What happens when we all come back together?

I've noticed for years that some of the first people to get sick in the fall are kids, teachers, and parents of school-aged children.

Researchers have noticed it too.

In one six-year study, respiratory infections in children consistently rose in September and peaked about two weeks after school opened.

And it wasn't necessarily "the flu."

Other research has found similar connections between school being in session, increased social contact, and respiratory illness.

It makes sense.

Hundreds of separate social networks suddenly reconnect.

Our social terrain changes.

But here's where this gets really interesting to me.

We don't just share germs

Our microbiomes aren't sealed inside our bodies.

Research has found evidence that microorganisms can be shared through families, households, and even broader social networks.

Think about that for a moment.

We talk about how the people closest to us influence who we become—our habits, attitudes, food choices, routines, and outlook on life.

But it's even bigger than that.

The people around us can influence our stress, sleep, behavior, emotional regulation, and aspects of our physiology.

And yes, we share microorganisms too.

Our relationships are part of our terrain.

And then there's the terrain inside the terrain

This may be my favorite part.

More than 30 years ago, researchers did something fascinating.

They assessed psychological stress in hundreds of healthy volunteers and then intentionally exposed them to respiratory viruses.

The volunteers were quarantined and monitored, so researchers could see who became infected and who actually developed a cold.

As psychological stress increased, so did susceptibility.

Clinical colds occurred in approximately 27% of people in the lowest-stress group compared with 47% in the highest-stress group.

Think about that.

Intentional viral exposure.

Different outcomes.

That doesn't mean our thoughts magically prevent illness.

It means the host matters.

Our terrain includes not only what we eat and the microorganisms living within us, but also the environment our bodies create in response to how we experience our lives.

So...how big is your terrain?

Zoom all the way out.

Our terrain is shaped by what's happening within us and around us—our microbiome, nervous and immune systems, thoughts and stress responses, food, relationships, homes, communities, and the natural world.

From the individual cell to the changing seasons, none of these things exist completely on their own.

We are ecosystems living within ecosystems.

Which is why I'm becoming less interested in asking only:

"What did you catch?"

Of course, what we encounter matters. Some microorganisms are helpful, some are harmless, and some can make us sick.

But exposure is part of being alive.

So perhaps there's another question worth asking alongside What is this?

What capacity does this body have to manage what it encountered?

Not as blame.

As curiosity.

Because the organism matters—and the condition of the host matters too.

That's where this conversation becomes empowering.

Tend the Terrain

We can't control every microorganism we're going to encounter, who our children sit beside, or everything circulating through the classroom, office, grocery store, or airplane.

And I don't think health should become an endless attempt to sanitize ourselves from the world.

Health isn't sterility. It's relationship.

So what can we influence?

• Nourish the body with nutrient-dense food and adequate protein.

• Protect sleep.

• Get outside and experience natural daylight.

• Move your body.

• Support healthy digestion and a diverse microbiome.

• Stay hydrated.

• Make room for rest and recovery.

And don't overlook the less tangible parts of your terrain—chronic stress, the thoughts and beliefs you repeatedly reinforce, and the relationships and environments that leave you feeling either depleted or supported.

Most importantly, tend to these things before you're sick.

That's what resilience means to me.

Not creating a body that never encounters a challenge.

Not creating a body that never gets sick.

But creating a body with greater capacity to meet a challenge, respond appropriately, recover, and return to balance.

The goal isn't to control everything we encounter.

The goal is to build our capacity to meet it.

And perhaps that's a much different way to think about preparing for "cold and flu season."

Maybe we're simply preparing ourselves for winter.

To your health and vitality,

💞 - Michele

A little science for the curious

Back-to-school respiratory infections: A six-year Israeli study found a predictable September increase in upper respiratory infections among children, peaking about two weeks after school began.

School sessions & respiratory illness: A seven-year Wisconsin analysis found an increased risk of respiratory infection while schools were in session, even after accounting for seasonal patterns, temperature, and humidity.

We share more than conversations: Research published in Nature Microbiology found evidence that human-associated microbes are shared along family and social networks.

Stress & susceptibility: In a controlled viral-challenge study published in The New England Journal of Medicine, psychological stress was associated with increased susceptibility to respiratory infection and clinical illness.

Want to Take This Conversation Further?

If this sparked questions—or made you start connecting a few dots of your own—let's keep exploring.

Join me Wednesday, October 14 at lunchtime for a live Zoom conversation.

This won't be a lecture or a presentation. Bring your questions, your observations, and the things that make you wonder, “Could these be connected?”

We'll explore terrain, resilience, immune health—and wherever our collective curiosity takes us.

Come curious. Let's explore together. 👇