The microbiome and the immune system are intricately connected. The trillions of organisms living inside us influence digestion, inflammation, metabolism, even mood.

What’s becoming more interesting is how specifically the recent research is mapping the gut’s influence on the immune system itself. The papers coming out over the past couple of years are starting to tell a more unified story. Because I’m so interested in this topic (for personal and professional reasons), I decided to do a deep dive into the recent literature on autoimmunity and the microbiome.

It really is fascinating how far the research has come.

Autoimmune diseases can look dramatically different clinically. But they often share surprisingly similar patterns in the gut.

Rheumatoid arthritis affects joints. MS affects myelin. Lupus can affect connective tissue and organs. Type 1 diabetes damages pancreatic beta cells. Psoriasis targets the skin.

Completely different organs. Completely different symptoms.And yet, when researchers look at the gut, something unexpected keeps showing up.

The deeper this research goes, the clearer it becomes that the gut may not just be associated with autoimmune disease. It may help set the stage for it.

This doesn’t mean the microbiome is the sole cause. Genetics, infections, hormones, stress, sleep, and environment all matter. But increasingly, the gut looks less like a bystander and more like part of the control center.

And that changes how we think about healing.

Because if the immune system is constantly listening to the gut, then the repeated patterns of our lives: what we eat, how we sleep, our stress, our movement, our medications, our environment, along with our genetics, are continually sending signals into that system.

Not in a fragile “one bad day ruins everything” kind of way. The body is remarkably resilient.

But over weeks, months, and years, those repeated inputs appear to shape the microbial environment, and the immune messages that come from it.

Not just calories. Not just digestion. Not just exercise.

Signals. Patterns. Information.

The Pattern Researchers Keep Finding

One of the most striking things about the 2025–26 reviews is how often they converge on the same picture.

A systematic review published in Cureus pulled together studies across lupus, rheumatoid arthritis, MS, autoimmune thyroid disease, psoriasis, and type 1 diabetes. Despite how different these diseases look clinically, the same core microbiome abnormalities kept showing up:

• Reduced microbial diversity

• A weakened intestinal barrier, allowing bacterial fragments to translocate

• Expansion of inflammatory species, especially Ruminococcus gnavus

• Collapsed production of beneficial metabolites like short-chain fatty acids

• A shift in immune tone away from regulation and toward inflammation

A large synthesis in Frontiers in Microbiomes drew the same conclusion across rheumatoid arthritis, lupus, MS, type 1 diabetes, IBD, and psoriasis. Different target organs. Different symptoms. Similar fingerprint in the gut.

Which raises an obvious question. If the microbial pattern is shared, why does one person develop arthritis and another develop MS?

The emerging answer: the gut may create the inflammation. Genetics decides where it lands.

Increased Intestinal Permeability, or “Leaky Gut,” Explained

I learned about “leaky gut” in my functional medicine training over a decade ago. Back then, the concept got dismissed pretty quickly in conventional circles. It belonged to the wellness world.

Fast forward to now, and researchers are measuring it directly.

The intestinal lining is only one cell thick. Those cells are held tightly together by proteins called tight junctions. When the junctions loosen, bacterial fragments, endotoxins like LPS, food antigens, and inflammatory compounds can pass into circulation.

This process is called translocation. And researchers can now measure it through specific biomarkers:

• Zonulin

• LPS

• I-FABP

• D-lactate

• Diamine oxidase

What’s interesting isn’t just that these markers go up in autoimmune disease. It’s that they often track with disease activity itself.

In Graves’ disease, elevated leaky-gut markers correlated with thyroid autoantibody levels. In lupus, certain strains of Ruminococcus gnavus bacteria were shown to directly induce zonulin-mediated permeability — and the degree of permeability tracked with lupus autoantibody levels. When researchers blocked zonulin, the permeability reversed completely.

It’s amazing that we can now trace this kind of chain at all — from a single bacterial strain, to a specific protein that regulates the gut barrier, to autoantibody levels in the blood, to a drug that intervenes in the middle of it. A decade ago we were arguing about whether leaky gut existed. Now we’re mapping the molecules.

Molecular Mimicry and Its Role in Autoimmunity

One of the most fascinating areas of this research involves something called molecular mimicry.

This is where bacterial proteins resemble human proteins closely enough that the immune system gets confused.

It attacks the microbe…

…and accidentally attacks you too.

The classic example is in lupus. Researchers found gut, skin, and mouth bacteria carrying proteins that look very similar to a human protein called Ro60. Ro60 is one of the first things the immune system attacks in lupus, often years before any symptoms show up. When they tested blood from lupus patients, the antibodies attacked both the bacterial and the human version of the protein.

Then they took mice raised in a sterile environment, with no bacteria in their gut at all, and gave them one of these bacteria. The mice started making antibodies against the human Ro60 protein and developed kidney damage similar to lupus, after only being exposed to the bacteria.

That’s molecular mimicry caught in the act.

And it’s part of why the microbiome no longer feels like a vague influence on autoimmune disease. It’s a biological process, with named molecules, identifiable bacteria, and reproducible experiments behind it.

The Microbiome Isn’t Just About the Bacteria. It’s About the Messages.

This is an important shift happening in the field.

Researchers are realizing the microbiome doesn’t primarily influence immunity through the bacteria themselves.

It influences immunity through metabolites, which are tiny signaling molecules the bacteria produce.

Take tryptophan, an amino acid from your diet. Gut bacteria break it down into small molecules that talk directly to immune cells. Those molecules help decide whether the immune system develops more:

• Regulatory cells that calm the immune response, or

• Inflammatory cells that drive autoimmunity

In other words, the microbiome is helping direct immune cell behavior through chemistry. And certain bacteria associated with autoimmune disease appear to hijack this system, tipping the balance toward inflammation.

Which means your gut microbes may be influencing, every day, whether your immune system calms down or stays activated.

That’s pretty amazing.

Autoimmune Disease Is More Complex Than the Microbiome… But the Microbiome Is an Important Signal

One thing we should be careful about here.

People sometimes hear microbiome discussions and think: “So if I fix my gut, I can cure my autoimmune disease.”

That’s not what the evidence says.

Autoimmune diseases are complex. Genetics matter. Environmental triggers matter. Hormones, infections, stress, sleep, metabolic health, and medication decisions all matter.

There is no one-size-fits-all plan, diet, or probiotic that will cure autoimmune disease.

But the evidence does increasingly suggest this:

Improving the gut can improve the terrain.

It may reduce inflammatory signaling, strengthen the gut barrier, support regulatory T cells, increase beneficial metabolites like short-chain fatty acids, and help shift the immune system away from constant alarm.

In some people, that can mean fewer symptoms, better resilience, improved labs, and lower disease activity. And for certain patients, gut dysfunction may be one of the root drivers keeping the immune system activated.

So no, this is not about magical probiotics. It is not about one stool test solving complex disease. And it is definitely not about replacing your doctors or your medical care.

But if your immune system is constantly listening to your gut, then healing the gut shouldn’t be optional background work. It may be one of the most important ways we help the body remember tolerance — the ability to tell self from foreign, and stand down when it should.

And if you ignore the gut entirely while trying to calm systemic inflammation, you may be missing one of the biggest immune-training systems in the body.

That’s why it’s worth paying attention to:

• Fiber intake

• Fermented foods

• Antibiotic history

• Sleep

• Stress

• Ultra-processed foods

• GI symptoms

• Food tolerance and intolerances

• Circadian rhythm

• Movement

• Diversity of plant intake

Because immunology increasingly is, too.

Putting the Science to Work

If the science feels exciting, the next question is the harder one: what do we actually do with it?

That’s where the following section gets practical.

We’ll walk through the conversations I have with patients every week: when to use fermented foods (and who they’re not right for), fiber diversity, whether stool tests are actually helpful, and which probiotics have the best evidence, as well as what’s emerging next in postbiotics, engineered bacterial therapies, and zonulin blockers.

Not a protocol. Not a supplement stack. Just an honest look at where the research points, where it doesn’t, and the patterns that consistently seem to help.

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When you think about aging, what comes to mind? Gray hair? Creaky joints? Chronic illness?

Fair enough. But here’s something else to think about: your gut is aging too. And it might be aging faster than the rest of you.

We’re talking about your microbiome, the roughly 38 trillion bacteria, fungi, viruses, and archaea that call your gastrointestinal tract home. This is not a minor supporting character in your health story. This is a lead actor. And as we age, some of those lead actors start phoning it in. Others leave the production entirely. And a few downright villainous understudies take their place.

But here’s the good news: this is one of the most modifiable systems in your entire body. The microbiome responds to what you eat, how you move, you’re time in nature and with others, and how you sleep, sometimes within days. The science here is genuinely exciting. And most importantly, actionable. Let’s dig in.

What Actually Happens to Your Microbiome as You Age?

Here’s the short version: it gets less diverse, more inflammatory, and less functional.

Here’s the longer version, because when we understand the science, we can make changes:

Interestingly, as we move from young adulthood through middle age and into our later decades, the gut microbiome undergoes predictable and measurable shifts. Research published in Aging and Disease (2025) describes how the microbial community is associated with tissue and organ function changes affecting the brain, bones, muscles, immune system, and vascular system. This isn’t just correlation. Increasingly, the evidence points to causation.

Specifically, here’s what shifts:

What decreases with age:

• Bifidobacterium -- your friendly, anti-inflammatory, gut-barrier guardian

• Faecalibacterium prausnitzii -- one of the most potent anti-inflammatory bacteria we know of

• Lachnospiraceae and Ruminococcaceae families -- key producers of short-chain fatty acids (SCFAs)

• Overall microbial diversity, which matters enormously

What increases with age:

• Proteobacteria (including E. coli) -- pro-inflammatory opportunists

• Pathobionts -- bacteria that behave themselves when they’re outnumbered, but become problematic as diversity drops

A comprehensive review in Frontiers in Aging (2025) confirmed this pattern: aging is associated with a decrease in microbial diversity alongside a rise in pro-inflammatory bacterial populations. These aren’t just academic observations. They have real clinical consequences. But here’s the empowering flip side: we know exactly what shifts these trends in the right direction.

Meet “Inflammaging,” and How You Can Turn It Down

There’s something that quietly happens as we age when we’re not paying attention. Researchers call it “inflammaging.”

Inflammaging is the chronic, low-grade, smoldering systemic inflammation that characterizes aging. It’s not the dramatic kind of inflammation you get from a sprained ankle or an acute infection. It’s more like a pilot light that never turns off, silently elevating interleukin-1 (IL-1), interleukin-6 (IL-6), and tumor necrosis factor-alpha (TNF-alpha) year after year.

Research published in Genome Medicine (2025) identifies inflammaging as a key driver of age-related diseases and highlights its bidirectional relationship with microbiome imbalances (or dysbiosis). In other words: an aging microbiome can fan the flames of inflammaging, and inflammaging can further disrupt the microbiome. It sounds like a tough loop, but the beautiful thing about loops is that you can enter them from either direction. Improve your microbiome, and you start turning down the inflammation. Turn down inflammation, and your microbiome has a better environment to thrive. These are win-win interventions.

How does the microbiome connect to inflammaging? Through your gut barrier.

Your gut lining is meant to be selectively permeable, letting nutrients through while keeping bacteria and their byproducts out of systemic circulation. Healthy gut bacteria, particularly the SCFA-producers, are responsible for maintaining this barrier. But when those beneficial microbes decline, the barrier weakens.

This is what is often called “leaky gut,” or intestinal hyperpermeability, and the science fully backs up the clinical concept. As the American Society for Microbiology’s 2025 review explains, when SCFA-producing bacteria decline, the gut barrier loosens. Bacterial fragments can seep into circulation, setting off an immune response that never fully resolves. Over years and decades, this contributes to cardiovascular disease, cognitive decline, autoimmune diseases, metabolic dysfunction, and frailty.

The good news? SCFA-producing bacteria are among the most diet-responsive microbes we know. Feed them well, and they come back.

What Centenarians Are Teaching Us

How do we know what a genuinely healthy aging microbiome looks like? They study people who’ve been doing it best for over a century.

The research on centenarian gut microbiomes is one of the most interesting threads in longevity science. Multiple studies across Italy, Sardinia, China, and Estonia converge on a striking pattern: people who live past 100 tend to maintain gut microbiome features that resemble younger, healthier adults.

Specifically, centenarians show elevated levels of Akkermansia muciniphila, Bifidobacterium, and Christensenellaceae -- all bacteria associated with metabolic health, gut barrier integrity, and reduced inflammation. A 2025 narrative review in the Journal of Biomedical Science describes the centenarian gut microbiome as characterized by increased microbial and metabolic diversity, enriched beneficial taxa, and enhanced gut homeostasis.

What’s particularly interesting is the Christensenellaceae finding. Genetics actually plays a role here, and research suggests that host genetics explains 30 to 40% of its abundance, but that still leaves 60 to 70% influenced by things you control. And research suggests that the rest of us can develop more centenarian-like guts through targeted lifestyle changes. The blueprint is literally already created and inside people who’ve lived to 100 in good health.

It’s Not Just Your Gut; It’s Your Whole Body

And we know from multiple recent studies that the microbiome doesn’t just affect digestion. Through connections from the gut to literally all parts of the body, such as the brain, bones, muscles, immune system, lungs, kidneys, and heart, and even skin, your microbial community has far reach throughout your entire body.

When SCFA-producing bacteria are abundant, they generate compounds like butyrate, propionate, and acetate that do extraordinary things: they support immune regulation, reduce neuroinflammation, maintain the blood-brain barrier, and improve insulin sensitivity, among many other functions.

A 2025 review in Frontiers in Aging links microbiome changes with age to frailty, neurodegenerative diseases, insulin resistance, and cardiovascular risk. The gut-brain axis, in particular, is remarkable. Age-related gut dysbiosis is associated with neuroinflammation and cognitive decline, while a healthy microbiome supports the production of serotonin, GABA, and other neurotransmitters that regulate mood, sleep, and cognition.

When your microbiome thrives, so does your brain. And that’s a relationship worth investing in for the long haul.

Signs Your Microbiome May Be Asking for Support

These are not diagnoses. They’re clinical signals to watch for as opportunities to intervene:

• New or worsening bloating and irregular bowel habits after years of digestive regularity

• Fatigue and brain fog that sleep and stress alone don’t fully explain

• New food sensitivities, especially to foods you used to tolerate fine

• Low-grade inflammation on labs (elevated hsCRP, fasting insulin)

• Increased susceptibility to infections -- the immune-microbiome interface is signaling for help

• Declining muscle mass despite adequate protein -- the gut-muscle axis may be contributing

• Mood shifts, including increased anxiety or low-grade depression without obvious cause

Think of each of these as a message, not a verdict. And the microbiome is one of the first places to address, because it’s also one of the first places to see things improve when we make targeted changes.

What You Can Actually Do

And this is the good news: the evidence that lifestyle and diet can meaningfully reshape the aging microbiome is robust, growing, and very hopeful.

The microbiome is a fast responder when you give it the right inputs.

1. Diet Is Your Most Powerful Tool, and the Fastest Acting One

Plant-predominant dietary patterns have been studied most extensively in aging. The NU-AGE trial followed over 1,100 older adults across five European countries for one year. Participants assigned to a Mediterranean-style diet showed significant improvements in gut microbiome composition, reduced frailty scores, and improved inflammatory markers. The authors concluded that improving habitual diet to modulate the gut microbiota has genuine potential to promote healthier aging.

Why does this dietary pattern work so powerfully? Several mechanisms work together:

• Diverse dietary fiber from legumes, vegetables, and whole grains feeds SCFA-producing bacteria, the butyrate-makers that maintain your gut barrier

• Polyphenols from berries, pomegranate, olive oil, and green tea have prebiotic-like effects and directly reduce inflammatory signaling

• Omega-3 fatty acids reduce gut inflammation and support barrier integrity

• Fermented foods like yogurt, kefir, kimchi, and sauerkraut provide live cultures that modulate microbial diversity

Clinical pearl: Aim for 30 or more distinct plant foods per week. Diversity of plants and fermented foods equal diversity of microbes. A 2021 Stanford study found this is likely the single most impactful nutritional change most people can make for microbial diversity.

2. Resistant Starch: The Secret Weapon That Packs a Powerful Punch

This one is exciting because it’s so simple, so affordable, and so easily accessible.

Resistant starch is a type of dietary fiber that your small intestine cannot digest, which means it travels to your colon intact, where it becomes a feast for your butyrate-producing bacteria. And butyrate is the metabolite that maintains your gut barrier, reduces inflammation, and supports everything from immune function to brain health.

The magic is in the cooking and the cooling. When you cook potatoes, rice, beans, or lentils and then let them cool in the fridge for at least 4 hours or overnight, the starches reorganize into resistant starch. This is called retrograde starch formation, and it meaningfully increases the resistant starch content of those foods.

What this looks like in practice:

• Cold potato salad with herbs

• Leftover rice, eaten cold or reheated gently (some resistant starch survives reheating)

• Bean salads or hummus made from chickpeas

• Overnight oats

• Slightly green bananas (resistant starch converts to regular sugar as they ripen)

Resistant starch from these sources increases the abundance of butyrate-producing bacteria, particularly Roseburia intestinalis and Faecalibacterium prausnitzii, two of the most anti-inflammatory organisms in the gut. So, the prescription may literally be cold potato salad.

One important note: start low, go slow. If you’ve been eating a low-fiber diet, resistant starch can cause some bloating initially as those bacteria ramp back up. Start with half a cup per day and build over 2 to 3 weeks. That temporary adjustment is actually a good sign; it means the microbiome is changing.

From Science to Strategy

The good news is that the aging microbiome is not helpless. It is responsive. And often, it changes faster than people expect when given the right signals.

Behind the paywall, continue reading about factors that really change the microbiome, a 90-day microbiome rejuvenation plan, the foods and fibers that most effectively feed butyrate-producing bacteria, the pre- and probiotic strains that are helpful in specific situations, and the tests are useful in clinical practice.

If you’ve been wondering how to move from interesting science to a healthier microbiome, read on.

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Life is full of literal and figurative mountains to climb. (I should know, I live in Colorado, where we have plenty of both!)

Some days, the slope feels manageable.
Other days, it feels nearly vertical.

But here’s what the science suggests:

How hard the climb feels has less to do with the mountain itself…
and more to do with who’s standing beside you.

In 2008, researchers at the University of Virginia asked students to stand at the base of a steep hill wearing heavy backpacks and estimate how steep it was. Some stood alone. Others stood next to a friend.

The hill was the same.
The weight was the same.

But the students with a friend beside them consistently rated it as less steep, and the longer they’d known that friend, the gentler the slope appeared.

“Social support changes how we perceive the world and how our bodies work.”
— Dennis Proffitt, PhD, psychologist and professor at the University of Virginia who studies perception and physical effort

It didn’t even require physical presence. In a follow-up study, participants who simply imagined a supportive person saw the hill as less steep than those who imagined someone neutral or negative.

And the closer they felt to that person, the easier the hill appeared.

That’s not metaphor.
That’s perception, literally, shaped by connection.

We tend to think of resilience as something internal. Something we build alone, in quiet moments of strength.

But this suggests something different:

The challenges we face aren’t just shaped by the world around us.
They’re shaped by the relationships within it.

The mountain isn’t entirely fixed.

It shifts depending on whether you feel supported… or alone.

And this isn’t just psychological; it’s physiological.

When you feel supported, your nervous system shifts.
Stress signals soften.
The body moves out of a constant fight-or-flight state.

Heart rate variability improves.
Inflammatory signaling quiets.
Energy becomes more available.

The same challenge…
but a different internal environment.

And over time, that changes everything.

So if the mountain feels especially steep right now, it may not be a sign to push harder.

It may be a sign to change the conditions around the climb.

This week’s small practice

Think of one person in your life who might be carrying more than they let on. Reach out, not to fix anything, not to have the perfect words, but simply to remind them they’re not alone.

And if you’re the one standing at the base of a steep hill, especially if it’s been a long one, or one you didn’t choose, start small.

You don’t have to explain everything.
You don’t have to be “doing better” first.

Just let one person in.

A text. A call. A quiet moment of honesty.

“I’m having a hard week.”

That’s enough to shift your internal state.
Enough to change how your brain and body experience what you’re facing.

You were never designed to carry all of this alone.

And sometimes, the first step isn’t climbing the hill…
it’s changing how your body perceives the climb.

Who is someone you can reach for today?
And whose shoulder might need yours?

Study reference:

1. Schnall, S., Harber, K. D., Stefanucci, J. K., & Proffitt, D. R. (2008). Social support and the perception of geographical slant. Journal of Experimental Social Psychology.

2. Smith, K. J., et al. (2020). The association between loneliness, social isolation and inflammation: A systematic review and meta-analysis. Neuroscience & Biobehavioral Reviews.

3. Uchino, B. N., et al. (2012). Psychological pathways linking social support to health outcomes. Social Science & Medicine.

We’ve all heard it.

Microplastics are everywhere.

In our water. In our food. In the air we breathe. And increasingly, in our bodies.

And even when we’re doing everything “right,” we’re still exposed.

A 2024 study found microplastics in every human blood sample tested. Another found them in lung tissue. Brain tissue. Even in placentas.

There is a lot of talk about steps to minimize exposure. But the question isn’t just how we avoid it.

It’s what can we do about what’s already getting in?

An Important Shift

Reducing exposure matters. A lot.

Minimize plastic containers. Filter your water. Be mindful of packaging. All worth doing.

But here’s the reality: you can do all of that and still accumulate nanoplastics daily just by breathing, eating produce, or drinking water.

So reducing exposure is the right starting point. It just can’t be the only one.

What if the more powerful move is interception? Catching these particles inside the gut, before they ever make it into circulation?

A recent study explored exactly that, and the answer came from a surprising place.

Fermented food.

The Study Worth Knowing About

Researchers at the World Institute of Kimchi in South Korea set out to answer a very specific question: can bacteria found in fermented foods actually bind to nanoplastics inside the gut?

Their findings were published March 19, 2026 in Bioresource Technology, the top-ranked journal in Agricultural Engineering.

The answer was yes. And it was surprising enough that the scientific community took notice almost immediately.

How the Study Was Done

The researchers screened multiple bacterial strains from kimchi, looking for any that could bind to polystyrene nanoplastics, the kind that form as everyday plastics break down and end up in our food and water.

Two strains stood out and were put through a series of tests. Both were tested across varying plastic concentrations, pH levels, and temperatures to see how reliably each one performed under different conditions.

Then came the one that really mattered: simulated intestinal fluid. The gut is acidic and harsh, nothing like a clean lab setting. Most strains fall apart under those conditions. One of these did. The other held up.

The stronger strain was then tested in mice. Half received the kimchi-derived bacterium alongside nanoplastics. Half did not.

The mice given the bacterium excreted more than twice the amount of plastic.

The Microbe That Caught Everyone’s Attention

The strain that held up was Leuconostoc mesenteroides CBA3656, a bacterium naturally present in kimchi.

What the researchers were testing was simple in concept but genuinely novel: could this microbe physically grab onto plastic particles in the gut?

Under standard lab conditions, it showed 87% adsorption efficiency. Nearly 9 out of 10 plastic particles, caught and held.

Impressive. But lab results don’t always translate.

In the simulated gut environment, a comparison strain collapsed from 85% all the way down to 3%.

CBA3656 held at 57%.

That gap tells an important story. Many microbes can’t survive the conditions of your intestine well enough to do anything useful. This one could.

And in the mouse experiments, animals given this bacterium excreted more than twice the nanoplastics compared to the control group.

More plastic leaving the body. Less staying behind.

Why This Is Worth Paying Attention To

Nanoplastics aren’t like larger microplastic fragments. They’re smaller than 1 micrometer, small enough to slip through the intestinal wall, enter the bloodstream, and accumulate in tissues.

Human autopsy research has found plastic concentrations higher in brain tissue than in the liver or kidneys. The FDA has acknowledged that nanoplastics can cross the blood-brain barrier.

We don’t fully understand the long-term effects yet. But the direction of this research is clear: the gut is where we have significant influence. Once these particles cross into circulation, our options narrow considerably.

The Bigger Idea Here

This study isn’t really about kimchi.

It’s about something much more interesting: a new role for the microbiome.

We already know gut bacteria influence inflammation, immunity, metabolism, and brain signaling. That conversation has been building for years, and it keeps expanding.

But this adds a different dimension, something almost mechanical:

Your microbiome may act as a physical filter between you and your environment.

Not just processing signals and nutrients but actively catching and removing harmful particles before they breach the gut barrier.

As lead researcher Dr. Se Hee Lee put it: “Plastic pollution is increasingly recognized not only as an environmental issue but also as a public health concern. Our findings suggest that microorganisms derived from traditional fermented foods could represent a new biological approach to address this emerging challenge.”

That’s a significant reframe. Your gut isn’t just a digestive organ. It may be one of your primary interfaces with the modern world, and the microbes living there may be doing more protective work than we’ve given them credit for.

How the Binding Actually Works

Leuconostoc mesenteroides CBA3656 uses a process called biosorption.

What this means is that specific structures on the bacterium’s cell wall act like microscopic hooks. They grab onto plastic particles and hold them, so instead of nanoplastics slipping through the gut lining and into your bloodstream, they get caught and carried out through normal digestion.

What makes this strain stand out is its staying power. Most bacteria lose their effectiveness in the acidic, churning environment of the intestine. This one keeps working.

This Is Still Early Research

This does not mean kimchi is a microplastic detox. It’s too early to make that claim.

This was one specific strain, tested in controlled lab conditions, with early animal data. Human trials haven’t been done yet. And we don’t know whether kimchi you buy or make is delivering this particular benefit at a clinically meaningful dose.

But I find this genuinely exciting work. The researchers screened hundreds of bacterial strains to find this one. That kind of rigor matters.

It’s also worth noting that this study focused on kimchi specifically because it was conducted by the World Institute of Kimchi, a South Korean government research institute. It wasn’t designed as a broad comparison across fermented foods.

The researchers themselves point to screening other fermented foods as a logical next step. Leuconostoc mesenteroides also appears in sauerkraut, certain yogurts, and other lacto-fermented vegetables, and there may be other strains with similar abilities that haven’t been tested yet. The kimchi angle is where this research started, but it likely won’t be where it ends.

What It Means Practically

We can’t eliminate exposure. At least, not yet. So the next question is: how do we support the systems that help our bodies handle it?

A resilient, diverse microbiome appears to be part of that answer.

Regular fermented foods. Microbial diversity. Protecting the gut environment.

Not as a trend. As a functional strategy with a growing body of research behind it.

The Takeaway

Health isn’t just about avoiding harm.

It’s about building resilience.

This study adds something meaningful to that idea: your gut microbes may be working harder than you realize, not just digesting food and managing inflammation, but potentially acting as a frontline defense against what the modern world puts into our bodies.

That’s worth knowing.
And honestly, worth building a resilient microbiome.

But this is where it becomes practical.

Because if your gut can help handle what you can’t fully avoid…
the next question is:

How do you actually support that system in real life?

Below are simple, effective ways to start using fermented foods intentionally, along with a beautiful, step-by-step recipe from Chef Martin that brings this to life.

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There’s a number that tells a surprisingly clear story about how much inflammatory fire your immune system is carrying right now.

You’ve almost certainly already had it measured.

You just didn’t know to look for it.

It lives inside the most common lab test in medicine: the complete blood count. The CBC. The test you get at every physical, glance at, see that your hemoglobin looks fine, and move on.

But buried inside that routine panel is something researchers and the longevity field are quietly getting excited about. A new way to read a test most doctors have been ordering for decades. A window into your immune system’s operating state that costs nothing extra to calculate, requires no new labs, and is sitting in your patient portal right now.

It’s called the Systemic Immune-Inflammation Index.

The SII.

And once you understand what it’s measuring, and why it matters, you’ll never look at a CBC the same way again.

How This Number Came to Exist

This isn’t a new test.

It’s a new calculation.

In 2014, a researcher named Hu and colleagues were trying to solve a very practical problem: after removing a liver cancer, which patients would recover well, and which wouldn’t?

They needed a signal that was simple, accessible, and already available in every hospital.

They found it hiding in plain sight.

Three ordinary numbers from a standard blood draw:

• Platelets

• Neutrophils

• Lymphocytes

Combined like this:

SII = (Platelets x Neutrophils) divided by Lymphocytes

That’s it. A simple equation.

And it worked.

It helped predict outcomes for those liver cancer patients. But then researchers started asking: what else could it tell us? Over the next decade, they applied it to heart disease, autoimmune conditions, diabetes, cognitive decline, aging itself.

The signal kept showing up.

What started as an oncology tool has quietly become one of the most widely studied inflammatory markers in medicine. And it costs nothing extra to calculate, because those three numbers are already sitting in your labs.

What It’s Actually Capturing

Each part of this equation is telling a different piece of the story.

Neutrophils are your immune system’s first responders. When the body senses a threat, whether infection, injury, a toxin, or even a blood sugar spike, they mobilize quickly. In a healthy system, they do their job and stand down. In a chronically inflamed system, they stay slightly activated. Low-grade. Persistent. Like a fire alarm that never quite turns off.

Platelets are usually thought of as clotting cells. And they are. But they’re also deeply involved in inflammation, especially inside blood vessels. When the vascular system is under stress from metabolic dysfunction, poor diet, or chronic inflammation, platelets become more reactive. Think of them as a signal of how much friction is building on the inside of your blood vessels.

Lymphocytes are your regulatory system. They represent the adaptive, intelligent arm of immunity: the part that learns, remembers, and keeps everything in balance. When lymphocyte levels are lower, it often reflects a system under strain from chronic stress, inflammation, or physiologic overload.

Put it all together, and the SII captures something specific:

The ratio of inflammatory drive to immune regulation.

More activation. Less balance.

That’s what a rising SII reflects.

What the Research Actually Shows

Here it gets even more interesting.

Over the past decade, researchers have been studying the SII across some very large populations. One study followed nearly 43,000 US adults for up to 20 years. Others have pooled data from hundreds of thousands of people across multiple countries and disease states.

The consistent finding: people with chronically elevated SII tend to have higher rates of cardiovascular disease, and other chronic conditions over time.

Now, a few things worth knowing before that lands the wrong way.

First, the SII goes up all the time, and that’s completely normal. Infection, injury, a hard week at work, a bad night of sleep. It rises, the body recovers, it comes back down. That’s your immune system doing exactly what it’s supposed to do. The research isn’t tracking those short-term fluctuations. It’s looking at people whose baseline, over years, stays elevated.

Second, this is observational research. That means we’re seeing patterns across large populations, not predicting any individual’s future. A higher SII doesn’t mean something is wrong with you. It means your immune system may be working harder than it needs to, and that’s worth paying attention to.

Think of it less like a warning sign, and more like a compass reading.

It tells you which direction the biology is trending. And the reason that matters is simple: the trend is changeable. Often significantly. Which is really the whole point of understanding it in the first place.

The Bigger Picture: Inflammaging

What the SII appears to capture is something we talk about often in medicine but rarely measure clearly:

Your body’s baseline inflammatory tone.

How hard your immune system is working.

How much regulatory reserve it has left.

In longevity research, there’s a term for what happens when this balance gradually shifts over time: inflammaging. Not a dramatic event. Not a single diagnosis. Just a slow drift toward a more inflammatory baseline, the kind that quietly underlies most chronic disease.

The SII tracks that drift.

And that’s actually an important opportunity. Because if you can see it, you can do something about it.

The Good News

This number is not fixed.

It rises when it should, during infections, injuries, surgery. That’s normal. That’s the body doing exactly what it’s supposed to do.

The question is simply whether it comes back down.

For many people, it doesn’t fully. Not because something is seriously wrong, but because the conditions of modern life, chronic stress, disrupted sleep, processed food, limited movement, keep the immune system quietly humming at a higher baseline than it needs to.

The encouraging part: this is one of the most modifiable markers in your biology.

The fundamentals we talk about don’t just “support health” in a vague way. They move this number. Sometimes more quickly than people expect. And once you know which levers matter most, the path forward becomes surprisingly clear.

Read on for the specific levers that move this number, the evidence behind them, and how to start shifting your immune system back toward balance.

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What It Means to Wish Someone Good Luck

In the emergency department, we used to ask each other a question during down time on those long shifts.

Would you rather be lucky or good?

It sounds like a thought experiment. But in the ER, it’s not abstract. You’re making decisions fast, with incomplete information, under pressure. Skill matters enormously. And yet, timing matters too. Who walks through the door. The patient’s anatomy, and how well the procedure goes. Whether you’re thinking clearly in that moment and order the right tests.

Some colleagues said good, without hesitation. One friend always said lucky, just as fast.

I always thought: both. You work hard. You develop your skills. You prepare. And then you hope that a little serendipity meets you halfway. Being in the right place at the right time can be life-changing. We’ve all seen it.

But I’ve been thinking about that friend who always said lucky, and about another friend whose relationship with luck has genuinely puzzled me for years.

The Ancient Ritual of Luck

Have you ever wished someone good luck?

Before an exam. A job interview. A big race. A surgery.

“Good luck.”

Two words. And almost always, something deeper moves behind them.

When someone says it to you, you feel it: a subtle shift in the body. A sense that someone is in your corner. A moment of warmth, connection, possibility. Your shoulders soften. Your mind settles. The future feels, briefly, more open.

But what are we actually doing when we wish someone luck?

Humans have been invoking it for thousands of years. Across cultures and centuries, people have always believed that something beyond pure effort shapes outcomes. The Romans carried amulets. Athletes might wear the same socks to every big game. Actors say “break a leg” before walking onstage. Even in medicine and science, fields built on evidence and rigor, people still lean in and whisper it.

“Good luck.”

It’s not a strategy. It’s not a plan. It’s hope, directed at another human being.

And modern science suggests those effects may be more real than we once assumed.

The Neuroscience of Feeling Lucky

Psychologist Richard Wiseman spent years studying people who described themselves as either “lucky” or “unlucky.” What he found wasn’t superstition; it was neuroscience.

People who believed they were lucky behaved differently in measurable ways. They noticed more opportunities. They were more relaxed in uncertain situations. More open to new experiences. They recovered more quickly when things went wrong.

In one controlled experiment, self-described “lucky” people were significantly more likely to spot an unexpected message printed in plain sight, because their brains weren’t locked into tunnel vision.

They weren’t necessarily luckier. They were neurologically more open to possibility.

The Friend Who had a Good Day When He Ran Out of Gas

I have a friend who says, almost reflexively: “Good things always happen to me.”

And they do. Somehow, they do.

For a long time I chalked it up to personality: optimism, maybe a selective memory. But watching him over the years, I’ve come to see something different. He doesn’t just receive good luck. He creates the conditions for it.

Once, he ran out of gas on the side of the road. Most of us would experience this as a minor disaster: the frustration, the inconvenience, the lost time. He experienced it as an unexpected introduction. The person who gave him a lift to the gas station turned out to be exactly the connection he’d been looking for.

The running out of gas didn’t knock him down. It opened a door.

It’s a great moment of serendipity. He was in the right place at the right time. And he had a nervous system and a mindset calibrated to see possibility where others see only problems.

What Happens in the Brain When Someone Roots for You

When someone sincerely wishes you good luck, something quiet happens in the nervous system.

Stress narrows attention. It puts the brain into threat-detection mode: scanning for danger, not opportunity. But when we feel supported, the brain shifts. Attention widens. Cognition becomes more flexible. Neuroscientists call this attentional broadening, and in practical terms, it means seeing the answer during a test, thinking clearly under pressure, or noticing the open door that others walk past.

Humans are deeply social creatures. Our nervous systems evolved in communities where survival depended on knowing whether others were with us or against us. When someone says “good luck,” they are doing something ancient: signaling I see you. I care what happens to you. I hope things go well.

That small moment of social support reduces cortisol. It increases psychological safety. And when the brain feels safe, it performs.

Maybe Luck Isn’t What We Think

Maybe luck isn’t a mysterious force, or maybe it is, and we’re simply learning how to work with it.

Maybe it’s a brain that stays curious instead of closed. A nervous system not trapped in chronic stress. A community that quietly roots for one another.

My friend in the ER who always said lucky; I think he understood something the rest of us were still working out. It wasn’t that he was leaving things to chance. It was that he stayed open to what chance might bring. He wasn’t rigid about how things were supposed to go.

Maybe luck is what happens when preparation, openness, and human connection converge, and we stay open to whatever the universe might offer.

And maybe those two words, “good luck”, are simply a small way of reminding someone:

You’re not doing this alone.

How to Make Yourself “Luckier”

The research is clear: luck can be cultivated. Small, repeatable habits quietly shift how the brain perceives and responds to the world.

Here are four evidence-based steps to bring a little more luck into your life.

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Part 3 of the Neuroinflammation Series

Your brain is protected by one of the most sophisticated security systems in biology.

A living wall of tightly sealed cells runs through nearly 400 miles of microscopic blood vessels, screening every drop of blood that passes through your brain.

Every second, it decides what gets in and what stays out.

When this system works well, your brain operates in a carefully protected environment, shielded from the inflammatory noise of the body.

When it begins to weaken, that noise seeps in.

And the consequences can begin long before anyone notices.

This is called the blood-brain barrier. And understanding it may change how you think about everything from brain fog to long-term neurological health.

In Part 1, we met the immune architecture of the brain: microglia, cytokines, the vagus nerve, the glymphatic system.

In Part 2, we explored the levers that lower neuroinflammatory load: sleep, movement, metabolism, gut health, and nutrition.

In Part 3, we go deeper into the structure at the center of it all.

The wall that protects your brain.

What happens when it’s compromised.

And why protecting it may be one of the most consequential things you can do for your long-term neurological health.

A Structure Unlike Anything Else in the Body

Most blood vessels in the body are fairly permeable by design. Nutrients, immune cells, and signaling molecules move in and out of tissues relatively freely. Under the right conditions, immune cells can leave the bloodstream and enter tissues to fight infection or repair damage.

The brain does not allow this.

The blood-brain barrier is formed by a specialized layer of endothelial cells that line the brain’s capillaries. What makes these cells extraordinary is how they connect to each other.

In most tissues, small gaps between capillary endothelial cells allow molecules to pass through. Brain endothelial cells are sealed together by tight junction proteins, claudins, occludins, and ZO-1, that form an almost seamless molecular wall.

Nothing slips between them. Because there are no gaps.

If you’re familiar with intestinal permeability, or “leaky gut”, the concept is similar here, but the brain’s version is even more selective. The tight junctions in the blood-brain barrier are more restrictive than those in the gut lining. The brain tolerates almost nothing that hasn’t been explicitly invited in.

But the BBB isn’t just a passive wall. It is actively maintained by a layered support system researchers call the neurovascular unit:

• Astrocytes — star-shaped glial cells whose “end-feet” wrap around capillaries, helping regulate what crosses into brain tissue

• Pericytes — cells embedded within the capillary wall that regulate blood flow and maintain tight junction stability

• The basement membrane — structural scaffolding that provides a second layer of filtration

• Microglia — the brain’s immune sentinels, patrolling just beyond the barrier at all times

Together, they form a coordinated living border control; one that runs twenty-four hours a day, without pause.

What the Barrier Does, and How It Does It

The blood-brain barrier performs several critical functions simultaneously.

It allows what the brain needs: glucose (transported via dedicated GLUT1 proteins), oxygen and carbon dioxide (which diffuse freely), amino acids for neurotransmitter synthesis, and fatty acids for membrane maintenance and myelin.

It blocks what would harm the brain: most pathogens, peripheral immune cells, large proteins, environmental toxins, and the majority of circulating molecules, including most pharmaceutical drugs. This is one reason treating neurological diseases is so pharmacologically challenging.

And it actively exports what doesn’t belong. Specialized efflux transporters, including a molecular pump called P-glycoprotein, push certain compounds back into the bloodstream even if they’ve managed to cross in.

The scale of this operation is worth pausing on.

The brain represents roughly two percent of body weight. It receives fifteen to twenty percent of the heart’s total blood output. Every drop flowing through brain capillaries is screened in milliseconds.

This is not passive filtration. This is active biological intelligence.

What Happens When the Barrier Breaks Down

The blood-brain barrier is not fixed.

It is dynamic, constantly adjusting to signals from the rest of the body. And under the wrong conditions, it can become more permeable than it should be.

When the tight junction proteins begin to loosen or degrade, several things happen:

• Inflammatory cytokines (IL-6, TNF-α, IL-1β) cross more easily and activate microglia (the brain’s inflammatory cells)

• Lipopolysaccharide (LPS), a bacterial endotoxin from the gut, can reach brain tissue and trigger neuroinflammatory signaling

• Peripheral immune cells begin trafficking into brain regions where they don’t belong

• Clearance of proteins like amyloid-beta becomes impaired; and what the brain can’t clear begins to accumulate

That last point is worth emphasizing.

Amyloid-beta may initially function as part of the brain’s defense, produced in response to infection or inflammation. But when inflammatory signals persist and clearance falters, this protective response can become self-reinforcing, allowing amyloid to build up in ways that contribute to disease.

Research increasingly suggests that blood-brain barrier dysfunction can occur years before neurodegenerative disease becomes clinically apparent.

The wall protecting the brain may begin weakening long before any symptom appears.

That’s the sobering part.

But here is what makes this worth understanding:

The blood-brain barrier is a living structure. It responds to signals. And many of those signals are ones we can influence.

Subscribers continue below for more discussion of what can damage this system, what neuroinflammatory stress actually feels like day to day, and evidence-based steps you can take every day to protect and strengthen the blood-brain barrier.

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Brain fog.
Low mood that feels out of proportion.
Fatigue that doesn’t resolve with rest.
A quiet sense that your mind isn’t as clear as it once was.

For many people, these symptoms feel mysterious. Unpredictable. Personal.

But increasingly, modern neuroscience is telling us something important:

They are often inflammatory.

In Part 1, we explored the brain’s immune architecture.

Microglia — the resident immune cells that patrol and respond.
The blood–brain barrier — the living border protecting neural tissue.
The glymphatic system — the sleep-dependent clearance pathway.
Cytokines and mitochondrial shifts — the molecular language of threat and energy conservation.

Now we ask the more important question:

If inflammation can rise in the brain, how do we help it fall?

The newest research is clear.

Neuroinflammation is not simply a side effect of brain disease.

It is central to it.

A 2025 review on Alzheimer’s disease progression highlights that chronic microglial activation does not merely sit alongside amyloid and tau pathology; it actively interacts with it, accelerating decline when inflammation fails to resolve. A June 2025 review in Science broadens the lens even further, describing neuroinflammation as a shared, central mechanism across Alzheimer’s, Parkinson’s, multiple sclerosis, traumatic brain injury, and even depression.

Inflammation is no longer viewed as background noise.

It is part of the engine.

Which means lowering inflammatory tone is not cosmetic.

It is biologically meaningful.
It is essential.
It is a path toward protecting, and improving, brain health.

And the hopeful truth is this:

Inflammatory tone responds to signals.

Signals we can influence.

Metabolic Stability: The First Lever

The brain is metabolically demanding and exquisitely sensitive to instability.

Sharp glucose spikes activate NF-κB, which is one of the body’s central inflammatory control switches, increase oxidative stress, and subtly weaken the blood–brain barrier, making it more permeable than it should be. Over time, this contributes to microglial priming, a state in which immune cells become sensitized and react more aggressively to smaller triggers.

When that happens, some of the symptoms people may feel include:

They feel foggy.
More irritable.
Mentally fatigued.
Less resilient to stress.

Not dramatically, just subtly off.

That’s what low-grade neuroinflammation often feels like.

And increasingly, research links metabolic dysfunction with faster neurodegenerative progression, in part through barrier compromise and amplified inflammatory cascades.

The goal isn’t perfection.

It’s steadiness.

Some simple steps we can take every day:

Beginning meals with clean protein and fiber.
Taking a short walk after eating.
Strength training consistently.
Reducing visceral adiposity gradually.

Stable glucose is interpreted as safety.

And the brain responds.

Sleep: Where Inflammation Resolves

During deep, slow-wave sleep, the space between brain cells expands. Cerebrospinal fluid flows more freely. Metabolic byproducts are cleared through the glymphatic system.

Short-term sleep disruption can temporarily raise inflammatory markers like IL-6 and CRP. Over time, however, chronic sleep fragmentation, not the occasional restless night, keeps microglia in a semi-activated state.

The newer literature reinforces something profound:

Impaired clearance and persistent inflammation amplify each other. When waste isn’t cleared effectively, inflammatory signals build, and that inflammation makes the cleanup system less efficient.

Deep sleep is not just restorative.

It is regulatory.

Morning sunlight anchors circadian rhythm. Consistent sleep timing stabilizes it. Dim evening light protects it. Strength training deepens slow-wave architecture.

Sleep is where inflammatory signals are recalibrated.

Muscle and Cardiorespiratory Fitness: An Anti-Inflammatory Organ System

Skeletal muscle is not just structural tissue.

It is endocrine tissue.

When muscles contract, they release myokines, signaling molecules that lower systemic inflammatory tone, improve insulin sensitivity, and increase brain-derived neurotrophic factor (BDNF), a key protein involved in learning and memory.

Higher cardiorespiratory fitness is consistently associated with reduced dementia risk and lower inflammatory burden. Emerging research shows that exercise alters circulating factors that directly influence brain function, suggesting that movement reshapes the immune–brain interface itself.

In contrast, loss of muscle shifts the immune system toward chronic activation.

Muscle contraction signals adaptation.

And adaptation quiets inflammation.

Stress Physiology and Human Connection

The nervous system and immune system are inseparable.

When the sympathetic nervous system remains chronically activated, the physiological state of ongoing stress, inflammatory signaling rises. Cytokines such as IL-6 and TNF-α increase. Microglial activation states shift. Blood–brain barrier permeability can change.

Imaging studies have shown that heightened amygdala activity, a marker of stress circuitry activation, predicts increased inflammatory output from the bone marrow and greater arterial inflammation. Loneliness, too, is associated with pro-inflammatory gene expression.

The emerging literature, including a 2025 Science review, emphasizes that neuroinflammation exists on a spectrum, dynamically shaped by metabolic inputs, peripheral immune signaling, and stress physiology.

And importantly, that spectrum moves in both directions.

Which means the counter-signals matter.

Slow diaphragmatic breathing.
Time outdoors.
Meaningful relationships.
Purpose-driven engagement.

These are not abstract wellness practices.

They are biologic regulators of inflammatory tone.

Omega-3 Fatty Acids: Structural and Signaling Resilience

Omega-3 fatty acids are foundational to neuronal architecture.

DHA is a structural component of brain cell membranes, helping maintain membrane fluidity and receptor function. EPA influences inflammatory signaling and supports the production of specialized pro-resolving mediators, which are molecules that actively help turn inflammation off.

A 2025 review examining natural compounds that influence microglial activation highlights omega-3s, along with polyphenols and sulforaphane, as modulators of NF-κB signaling and oxidative stress pathways within microglia.

In other words, dietary patterns rich in omega-3 fatty acids and colorful, polyphenol-dense plants do more than “reduce inflammation.”

They influence microglial behavior directly.

For those who eat fish, that may mean incorporating fatty fish regularly. For those who don’t, it means ensuring a reliable source of omega-3s through thoughtful dietary planning or supplementation. It also means limiting excess ultra-processed omega-6 oils and prioritizing deeply pigmented, plant-rich foods, especially polyphenol-dense fruits, vegetables, and cruciferous plants.

This is not just anti-inflammatory eating.

It is structural resilience for the brain

The Gut–Brain Axis

The gut and brain are in constant conversation, through immune signaling, microbial metabolites, and the vagus nerve.

When the gut barrier is compromised, circulating lipopolysaccharide (LPS), a bacterial endotoxin, can enter the bloodstream. Even at low levels, LPS can elevate systemic cytokines and influence microglial activation.

For some people, that upstream immune activation may show up not as digestive distress, but as brain fog, fatigue, lower stress tolerance, or subtle mood shifts.

The gut and brain are deeply intertwined. When one is inflamed, the other often feels it.

A diverse, fiber-rich dietary pattern supports butyrate production and microbial stability, both of which help maintain gut integrity. Addressing chronic constipation and limiting ultra-processed foods further reduces inflammatory signaling upstream.

When the signals from the gut quiet, the signals reaching the brain often quiet as well.

A calmer gut frequently translates to a calmer brain.

Environmental Load

Environmental load also matters.

Air pollution and particulate matter have been associated with increased neuroinflammatory markers and higher dementia risk. These exposures can activate microglia and contribute to oxidative stress within the brain.

We cannot eliminate all environmental exposure. But we can reduce cumulative burden.

Improving indoor air quality.
Filtering drinking water when appropriate.
Avoiding tobacco smoke.
Choosing whole foods over highly packaged ones.

Lower total load means lower inflammatory signaling.

Less signal, less activation.

The Integration

The emerging science of 2025 reinforces something both sobering and empowering:

Neuroinflammation is dynamic.
It responds to context.

When metabolic instability, sleep disruption, muscle loss, chronic stress, omega-3 insufficiency, gut-derived immune activation, and environmental burden accumulate, microglia remain activated.

When those signals shift, microglia recalibrate.

The brain is not fragile.

It is adaptive.

And when we consistently move these levers, we don’t just lower inflammatory markers.

We influence trajectory.

That is what the newest literature is telling us.
That is why these daily choices matter.

This is the deeper message of this neuroinflammation series:

Inflammation rises in context.
And it quiets in context.

When we change the signals, we change the trajectory.

We support the brain’s capacity to recalibrate, repair, and remain resilient.

References:

· Neuroinflammation across neurological diseases, Science, 2025

· Role of neuroinflammation in neurodegeneration development, Nature, 2023

· The role of comorbidities in the associations between air pollution and Alzheimer’s disease: A national cohort study in the American Medicare population, PLOS Medicine, Feb 2026.

· Long-term air pollution exposure and incident dementia: a systematic review and meta-analysis, The Lancet, 2025.

· Microglia in neurodegenerative diseases: mechanism and potential therapeutic targets, Nature, 2023.

· The effects of resistance exercise on cognitive function, amyloidogenesis, and neuroinflammation in Alzheimer’s disease, Frontiers in Neuroscience, 2023.

· Does resistance training in older adults lead to structural brain changes associated with a lower risk of Alzheimer’s dementia? A narrative review, Aging Research Reviews, 2024.

· N-3 Polyunsaturated Fatty Acids and the Resolution of Neuroinflammation, Frontiers in Pharmacology, 2019.

· Neuroinflammation, Sleep, and Circadian Rhythms, Frontiers in Cellular and Infection Microbiology, 2022.

· Sleep disturbance induces neuroinflammation and impairment of learning and memory, Neurobiology of Disease, 2012.

Your brain is extraordinary.

It weighs about three pounds.
Consumes ~20% of the body’s resting energy.
And it holds your memories, your language, your personality, your creativity, your love.

And here’s what’s even more remarkable:

Your body has built multiple layers of protection around it.

Border control.
Resident immune cells.
Chemical messengers.
Emergency responders.
Waste removal systems.
A braking system.

This is layered biological intelligence.

Most of the time?

It works beautifully.

Until the signals stay elevated too long.

The Brain Is Not Separate From the Immune System

For years, we were taught the brain was “immune privileged” and sealed off from the immune system.

But we now know that’s not true.

The brain has its own immune cells.
It communicates constantly with the body.
It responds to inflammation, stress hormones, blood sugar shifts, sleep quality, and gut health.

When inflammation rises in the body, the brain feels it.

Not dramatically at first.

Quietly.

A little slower recall.
A little more irritability.
More mental fatigue.
Less resilience.

The brain doesn’t burn loudly.

It smolders.

To understand why, we need to meet the players.

The Cast of Characters

Think of this as a coordinated team.

Each has a role.

When they work together, you feel sharp and steady.

When signals stay elevated too long, the system shifts into protection mode.

1. Cytokines: The Immune Messengers

Cytokines are small signaling proteins released by immune cells.

They are not destructive by design.

They are essential.

Cytokines help:

• Coordinate immune defense

• Promote healing

• Clear infections

• Repair damaged tissue

Without cytokines, we couldn’t survive injury or infection.

Some of the most studied inflammatory cytokines include:

• Interleukin-6 (IL-6)

• Tumor necrosis factor alpha (TNF-α)

• Interleukin-1 beta (IL-1β)

These rise appropriately when the body detects:

• Infection

• Injury

• Metabolic stress

• Autoimmune activity

• Psychological stress

When you have the flu, cytokines increase.

You feel tired. Foggy. Achy.

That’s not weakness.

That’s intelligent energy conservation.

The problem is not cytokines.

The problem is chronic, low-grade elevation.

When IL-6, TNF-α, and IL-1β stay mildly elevated for months or years, from persistent stress, poor sleep, insulin resistance, visceral fat, or gut imbalance, your brain keeps receiving the signal:

“Something is wrong.”

(If you’ve ever had an elevated hsCRP on labs, that can be a reflection of this same ongoing immune signaling.)

And it adapts.

2. The Blood–Brain Barrier: The Gatekeeper

Your brain is protected by a highly selective filter called the blood–brain barrier (BBB).

It’s made of tightly packed endothelial cells lining brain blood vessels.

Its job is to regulate:

• What enters

• What stays out

• What is tightly controlled

Glucose and oxygen? Allowed.
Toxins and pathogens? Blocked.

It is precise.

But it is sensitive.

Chronic inflammation, oxidative stress, repeated glucose spikes, sleep deprivation, and prolonged stress hormones can weaken those tight junctions.

When that happens:

• The barrier becomes more permeable (think “leaky brain”)

• Inflammatory signals cross more easily

• Brain immune cells activate

The border softens.

And the brain feels it.

3. Microglia: The Brain’s First Responders

Microglia live inside your brain.

They are its resident immune cells.

When they detect danger signals, including cytokines that cross the BBB, they activate.

In short bursts, they:

• Clear debris

• Protect neurons

• Coordinate repair

That’s healthy inflammation.

But if the alarm never stops, microglia remain activated.

Chronically activated microglia can:

• Release more inflammatory cytokines

• Alter neurotransmitter balance

• Interfere with neuronal communication

Like firefighters who never receive the “all clear,” constant activation eventually causes collateral damage.

4. Neurotransmitters: The Communication Network

Neurons communicate using chemicals (neurotransmitters) like:

• Serotonin

• Dopamine

• GABA

• Glutamate

Inflammation influences how these are produced and regulated.

For example:

Inflammatory cytokines can shift tryptophan away from healthy serotonin production and toward the neuroactive kynurenine pathway.

This may contribute to:

• Lower mood

• Brain fog

• Anxiety

• Reduced cognitive flexibility

This is not a mindset failure.

It’s immune signaling affecting brain chemistry.

5. The Gut Microbiome: The Upstream Regulator

Your gut microbes play an essential role. They help regulate immune tone.

They:

• Train immune cells

• Produce anti-inflammatory short-chain fatty acids like butyrate

• Influence cytokine production

• Communicate with the brain through immune and neural pathways

When microbial diversity drops or gut barrier integrity weakens (as in “leaky gut”):

• Systemic inflammation rises

• Cytokine signaling increases

• The brain responds

The gut and brain are not separate systems.

They are in constant dialogue.

6. The Vagus Nerve: The Brake Pedal

The vagus nerve is like a thermostat for inflammation.

When it senses that the inflammatory response is getting too high, it sends a signal using a chemical messenger called acetylcholine.

That signal tells immune cells:

“You can calm down now.”

This built-in brake system prevents inflammation from escalating unnecessarily.

When vagal tone is strong:

• Inflammatory signaling is better controlled

• Stress recovery improves

• Heart rate variability improves

When vagal tone is low:

• Inflammation is amplified

• Microglia are more easily activated

It’s the braking system on immune reactivity.

Many of us are living with too much accelerator and not enough brake.

How It All Connects

Stress, metabolic dysfunction, poor sleep, or gut imbalance
→ Cytokines increase (IL-6, TNF-α, IL-1β)
→ CRP rises as a measurable reflection
→ Blood–brain barrier becomes more permeable
→ Microglia activate
→ Neurotransmitters shift
→ Brain fog, fatigue, mood changes

This is not random.

It’s a coordinated adaptive response.

And importantly:

It is modifiable.

The brain doesn’t suddenly fail.

It adapts to signals.

And if we lower the inflammatory load, we often see improvement in:

• Focus

• Mood

• Sleep

• Energy

• Cognitive resilience

Not because we forced the brain to work harder.

But because we removed some of the fire.

What This Means for You

Understanding the biology is important.

But what matters more is this:

How does this apply to you?

Below, we’ll explore what this framework means personally, and why it should give you hope.

Read more

Histamine is an essential part of the immune system.
We cannot live without it.

In Part 1, we talked about histamine as information, not the enemy, but a messenger. A molecule that helps regulate immune defense, digestion, circulation, and wakefulness.

But what happens when the messenger won’t quiet down?

When every meal feels unpredictable.
When stress amplifies symptoms.
When sleep fractures.
When antihistamines help… but only partially.

If histamine feels like it’s running your life, you are not alone.

Many people navigating food sensitivities, flushing, GI symptoms, anxiety, insomnia, or autoimmune flares eventually hear terms like histamine intolerance or MCAS and begin to wonder:

Is this what’s happening to me?

Before we go further, let’s ground this.

Histamine dysregulation exists on a spectrum.

For many, what appears to be mast cell activation is not a rare or mysterious disease. It is a regulatory system that has become strained and overly reactive.

And strained systems can regain balance.

(If you haven’t read my previous post, Part 1: When the Body Becomes Reactive, start there for a deeper look at what histamine is, why we need it, and how it becomes dysregulated.)

MCAS: What It Is (and What It Isn’t)

Mast cell activation syndrome describes a pattern of exaggerated or poorly regulated mast cell activation.

It is:

• Multi-system

• Fluctuating

• Trigger-sensitive

• Often stress-responsive

It is not:

• Automatically permanent

• A reason to panic

• A life sentence of elimination diets

In most cases, mast cells become reactive because the terrain is inflamed, overloaded, or poorly regulated.

The solution isn’t fear.
It’s stabilization.

Why Avoidance Alone Often Fails

Low-histamine diets can reduce symptoms.

But when restriction becomes the only strategy, something else happens:

• Microbial diversity drops

• Nervous system vigilance rises

• Tolerance narrows

• Reactions become more unpredictable

Avoidance can reduce noise.
It does not rebuild resilience.

If done for long periods, it can cause more harm than good.

To calm histamine long term, we don’t just eliminate triggers.

We rebuild regulation.

That means supporting:

· Immune tone

· Circadian rhythm and sleep

· Nervous system regulation

· Hormonal stability

· DAO function and nutrient optimization

· Microbial diversity

In some cases, it also means strategically using medications to stabilize a reactive system while deeper regulation is restored.

Emerging research, including interesting work on metabolic signaling and GLP-1 pathways, suggests we may be on the edge of a broader understanding of mast cell regulation.

This is more than elimination diets.
And more than medications.

It’s a systems approach.
A practical framework for rebuilding resilience, with some new cutting-edge science.

Let’s go deeper….

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Part 1

I’m having this conversation more and more frequently, and I wanted to share.

It feels like it’s becoming more common, or perhaps I’m simply better at recognizing it now. Either way, I’m seeing more people with food sensitivities, worsening allergies, unpredictable GI symptoms, anxiety and poor sleep, and autoimmune conditions that feel harder to calm, even when they’re doing all the “right” things.

What makes these conversations especially meaningful for me is that I’ve been there too.

Years ago, before I had language for what was happening, my body became increasingly reactive. Foods that once felt safe suddenly didn’t. Symptoms came and went without a clear pattern. I felt inflamed, overstimulated, and confused by how sensitive my system had become.

At the time, I didn’t know what histamine was, or how central it could be to so many seemingly unrelated symptoms.

Now, years later, I recognize the pattern immediately.

A Pattern I’m Seeing Everywhere

In patient visits, inboxes, and conversations, the story sounds familiar:

• “I suddenly react to foods I used to tolerate.”

• “My allergies are worse than they’ve ever been.”

• “My gut feels unpredictable.”

• “My autoimmune symptoms flare for no clear reason.”

• “Everything inflames me.”

These symptoms don’t always show up together.
They don’t follow classic allergy rules.
And they often fluctuate.

But very often, they share a common contributor:

Excess histamine.

Not as a diagnosis.
Not as a label.
But as a physiologic signal that the body is carrying more load than it can comfortably regulate.

Histamine Isn’t the Problem; It’s Essential

Histamine has a bad reputation.

Most people associate it with allergies, antihistamines, and seasonal misery. But histamine is not a mistake. It’s a critical signaling molecule, one we quite literally cannot live without.

Histamine plays an essential role in how the body functions and protects itself. It’s involved in:

• Immune defense and threat detection

• Communication between immune cells

• Regulation of stomach acid and digestion

• Wakefulness and alertness in the brain

• Blood vessel permeability and tissue repair

• Circadian rhythm and sleep–wake signaling

In other words, histamine keeps us alive.

The issue isn’t histamine itself.
The issue is too much histamine, for too long, in a system that can’t clear or regulate it well.

Histamine in the Brain

In the brain, histamine acts as a neurotransmitter.

It plays a key role in wakefulness, attention, and circadian rhythm. Under normal conditions, histamine helps us feel alert during the day and allows sleep pressure to build naturally at night.

When histamine signaling becomes excessive, or poorly timed, it can contribute to:

• Insomnia

• Anxiety or internal restlessness

• Early-morning waking

• That familiar wired-but-tired feeling many people describe

This isn’t a character flaw or a stress-management failure.
It’s biology.

Where Histamine Comes From

Histamine is produced and released by several key players in the body:

• Mast cells and basophils - immune “sentinel” cells; think of them as the body’s early-warning system

• Cells lining the stomach - where histamine helps regulate digestion

• Neurons in the brain - where histamine functions as a neurotransmitter

• Certain gut microbes, - which can influence overall histamine load

Histamine acts through four different receptors (H1–H4). This is why it can affect many systems at once: skin, gut, lungs, blood vessels, and brain.

And it’s why histamine-related symptoms can look so different from one person to the next.

How Histamine Becomes Excess

It’s helpful to understand how histamine functions when the system is working well.

But what matters here, and what many people are experiencing now, is what happens when that balance is lost.

Histamine overload is rarely caused by a single factor. More often, it reflects system-level imbalance, with multiple signals converging at once.

This is worth emphasizing: it’s usually not just one trigger. We often search for the food, the exposure, or the supplement that sets everything off. In reality, histamine dysregulation is typically more complex, and more interconnected, than that.

Here are the most common pathways.

1. Histamine Is Overproduced

Chronic immune activation, such as autoimmune disease, ongoing infections, environmental exposures, mold, or persistent inflammation, can keep mast cells in a primed, hyper-reactive state.

Instead of releasing histamine briefly and appropriately, these cells begin to release it too easily and too often, even in response to signals that once felt neutral.

2. Histamine Isn’t Broken Down Efficiently

Histamine is cleared primarily by an enzyme called DAO (diamine oxidase) in the gut.

DAO activity can be reduced when there is:

• Gut inflammation

• Nutrient insufficiency

• High overall histamine load

• Genetic variation

When histamine clearance is impaired, histamine lingers and symptoms build.

3. Gut Dysbiosis Shifts the Balance

Some gut bacteria produce histamine, while others help regulate and break it down. This is yet another way the microbiome communicates with the nervous and immune systems: histamine can even act as a signaling molecule in the gut–brain axis.

When the microbiome is disrupted, often by stress, illness, antibiotics, or poor diet, that balance can shift toward higher histamine signaling.

This helps explain why gastrointestinal symptoms and histamine-related symptoms so often appear together.

4. Stress and the Nervous System Play a Major Role

Mast cells sit right next to nerve fibers, especially in the gut, skin, lungs, and brain. They are in constant communication with the nervous system.

The vagus nerve normally helps keep this system in balance, acting as a regulatory brake on immune activation and histamine release.

When the nervous system is under chronic stress and vagal tone is low, that brake weakens. Mast cells become more reactive, histamine is released more easily, and recovery takes longer.

This helps explain why histamine-related symptoms often worsen during emotional stress; even when food hasn’t changed.

It also explains why supporting the nervous system and gently stimulating the vagus nerve are often essential early steps in healing.

5. Circadian Rhythm Matters More Than We Think

Histamine follows a daily rhythm.

Disrupted sleep, late and irregular meals, nighttime cortisol spikes, and irregular light exposure can all amplify histamine signaling, especially symptoms like:

• Insomnia

• Anxiety or restlessness

• Nighttime awakenings

• Early-morning flares

For many people, histamine symptoms are as much about timing as they are about triggers.

Symptoms Commonly Linked to Histamine Excess

Histamine dominance doesn’t look the same in everyone.

It may show up as:

• Flushing or redness

• Itching, hives, or rashes

• Nasal congestion or post-nasal drip

• Bloating, diarrhea, reflux, nausea, or IBS symptoms

• Headaches or migraines

• Palpitations or lightheadedness

• Anxiety or internal restlessness

• Poor sleep or early waking

• Brain fog or fatigue

• Joint pains, stiffness

One of the biggest clues is variability.

Symptoms change:

• Day to day

• Meal to meal

• Stress to stress

This unpredictability is often what leaves people feeling confused and frustrated.

Why This Is Becoming So Common

We are living in a time of:

• Higher immune burden (more frequent or ongoing immune activation)

• More environmental exposure

• Disrupted gut ecosystems

• Chronic stress with little recovery

• Circadian rhythm disruption

• Isolating lifestyles

For many people, histamine becomes the messenger for a system that’s overloaded.

Not broken.
Not weak.
Just stretched beyond what it can easily regulate.

When immune and nervous system activation persists, mast cells can become more reactive. Histamine release becomes less predictable, symptoms broaden, and reactions happen more easily. Over time, this pattern may progress into what’s often called mast cell activation syndrome (MCAS), which exists along a spectrum. More on this soon.

The Most Important Takeaway

Histamine is not the enemy.
It is information.

And when histamine symptoms appear, the most important question isn’t:
“What’s wrong with me?”

It’s:
“What is my body responding to, and how can I help it regain balance?”

Coming Next

In the next article, we’ll explore:

• Why histamine issues are common in autoimmune disease

• Mast cell activation and MCAS - what it is, and what it isn’t

• Why avoidance alone doesn’t solve the problem

• A systems-based approach to calming histamine

Because the goal isn’t to eliminate everything. (Although it may feel that way sometimes).

It’s to help your body feel safe again.

Arteries and Aging, Our Lifelines, Part 3

We’ve talked about flexibility.
We’ve told the story of the endothelium.

Now comes the natural question.
What do we actually do?

Not in a frantic, optimization-obsessed way.
But also not casually or passively.

Cardiovascular disease remains the leading cause of death in both men and women, and endothelial health sits at the center of that risk. This makes caring for our blood vessels essential; not someday, but now.

The good news is that this doesn’t need to be fueled by fear.
It requires steadiness and attention.

Endothelial health is not built in a week.
It is built through patterns.

And the encouraging part is this:
the endothelium is remarkably responsive. When it receives the right signals consistently, over time, it adapts, stabilizes, and heals.

That is where meaningful prevention lives.

The Frame That Matters Most

Before we get specific, one mindset shift matters more than any supplement or protocol.

Endothelial health is not just about chasing numbers (although numbers do matter). It’s about sending the right signals, repeatedly, over time.

When those signals are supportive:

• Nitric oxide production improves

• Vessels remain flexible

• Inflammation quiets

• Repair pathways stay active

This is about learning to do the right things often enough to support endothelial health.

The Five Signal Domains That Protect the Endothelium

While it’s important to look at labs and studies, we can also talk about signals.

There are five major domains that communicate directly with the vessel lining.

1. Movement (Mechanical Signals)

For the endothelium, movement is information.

As blood flows across the vessel wall during activity, it creates shear stress. This mechanical signal tells endothelial cells to remain flexible and continue producing nitric oxide.

The most reliable signals come from:

• Regular walking

• Cycling or swimming

• Resistance training

• Any rhythmic movement that increases blood flow without overwhelming the system

Intensity also has a role.
But consistency matters too.

The endothelium responds best to signals it can trust.

2. Muscle (Metabolic Protection)

Skeletal muscle is one of the endothelium’s greatest allies.

Healthy muscle improves:

• Glucose handling

• Insulin sensitivity

• Inflammatory signaling

• Blood flow dynamics

Resistance training does not just build strength.
It protects the vascular system and improves the metabolic environment the endothelium lives in.

This is especially important with aging, inflammation, or insulin resistance.

3. Food (Chemical Messaging)

Food is not just fuel.
It is messaging.

Some patterns calm the endothelium.
Others keep it in a reactive state.

Supportive patterns tend to:

• Limit repeated glucose and insulin spikes

• Reduce oxidative stress

• Support nitric oxide signaling

• Provide antioxidants and polyphenols

• Promote a healthy microbiome and anti-inflammatory signaling

Injurious patterns tend to:

• Promote inflammation

• Increase oxidative burden

• Reduce nitric oxide availability

• Damage the endothelium

This is not about perfection or restriction.
It is about the direction of the signal over time, and the more protective, the better.

The endothelium remembers patterns.

4. Rest and Repair (Nighttime Biology)

A large portion of endothelial repair happens at night.

Poor or fragmented sleep:

• Increases sympathetic tone

• Raises inflammatory signals

• Reduces nitric oxide production

• Impairs vascular repair

Sleep is not passive recovery.
It is active maintenance of the vessel lining.

If endothelial health is a goal, sleep has to be protected.

5. Inflammation Load (The Background Noise)

Chronic inflammation changes how the endothelium behaves.

When inflammation is present, the vessel lining is working in a louder, more demanding environment, often long before symptoms or imaging abnormalities appear.

Autoimmune disease, metabolic dysfunction, chronic infections, and ongoing environmental exposures all raise the baseline stress on the endothelium.

Studies show increased cardiovascular risk in autoimmune disease, even with diet and lifestyle changes. This risk is not just about cholesterol or plaque. It reflects ongoing immune activation interacting directly with the vessel lining over time.

Viral illnesses can add to this burden as well. Some infections cause short-term endothelial stress. Others leave behind a longer inflammatory imprint that affects vascular signaling and repair.

And it’s not only major diagnoses that matter.

Any ongoing inflammatory process can place strain on the endothelium.

Chronic allergies.
Asthma.
Gum disease.
Recurrent infections.
Low-grade, persistent inflammation of many kinds.

All of these contribute to the background noise the vessel lining has to interpret and manage every day.

In these settings, lifestyle remains foundational and essential.

But it may not always be sufficient on its own.

This is where additional support becomes protective rather than optional, helping to calm inflammatory signaling, stabilize the vessel lining, and protect long-term vascular health while healing takes place.

This is where nuance matters.

Below, we move into how this roadmap becomes individualized.

• Specific foods to protect the endothelium

• When lifestyle is enough

• When it is not

• How to think about supplements and medications as endothelial protection

• Which labs and imaging actually reflect endothelial health

• And how to think in decades, and long-term protection

If the endothelium is the story, this is the strategy.

Read more

Arteries & Aging: Our Lifelines, Part 2

Most people think cardiovascular disease begins with cholesterol.

But it is far more complex than that.

It begins much earlier, quietly, at the level of the blood vessel lining.

Long before a plaque appears.
Long before a scan turns abnormal.
Long before anyone feels a symptom.

That lining is called the endothelium.

And how well it functions may be one of the most important determinants of how we age.

Why Blood Vessels Matter More Than We Realize

Your blood vessels are not just tubes.

They are your lifelines: a vast, dynamic network that delivers oxygen, nutrients, hormones, and immune signals to every cell in your body, and carries away carbon dioxide and metabolic waste.

Every organ depends on how well this system works.

And here is an important point:

Blood vessels are not passive pipes.

They are living, sensing, responding organs.

How flexible they are.
How inflamed or calm they become.
How easily blood flows or struggles to move forward.

All of this is determined by a microscopic layer of cells lining the inside of every vessel.

The Thin Layer That Changes Everything

Lining every artery, vein, and capillary is a surface just one cell thick.

This is the endothelium.

Despite its size, it plays an outsized role in health and longevity.

Sitting on top of this lining is an even more delicate structure called the glycocalyx: a thin, gel-like coating that helps protect the endothelial cells and regulate what passes between blood and tissue.

Together, these form a highly intelligent interface.

Every second, the endothelium is taking in information from the bloodstream and the body around it:
Blood flow.
Pressure.
Glucose.
Lipids.
Inflammatory signals.
Stress hormones.
Mechanical forces from movement.

Based on those signals, it makes moment-to-moment decisions:

• When to dilate or constrict blood vessels

• How smoothly blood flows

• Whether inflammation is turned up or dialed down

• Which nutrients are allowed to pass into tissues

• How metabolic waste products move back into circulation

• Whether clotting is promoted or restrained

This is not plumbing.

It is biology with intention.

When the Endothelium Is Healthy

When the lining is well supported, the system works quietly and efficiently.

Blood vessels relax easily.
Nitric oxide, a key signaling molecule, is plentiful.
Blood pressure adapts instead of spiking.
Exercise feels energizing rather than depleting.
Nutrients move smoothly into tissues.
Waste products are cleared without friction.
Repair happens in the background, without fanfare.

This is what healthy aging looks like at the vascular level.

Not perfection.

Responsiveness.

A Brief but Important Clarification

Not all endothelium starts from the same place.

Some people inherit vessels that are naturally more resilient.
Others are born with biology that makes the endothelial lining more vulnerable to inflammation, oxidative stress, or impaired nitric oxide signaling.

This helps explain why two people can live similarly and still age very differently.

Lifestyle and diet are foundational for everyone.
For many people, consistent attention to movement, nutrition, sleep, and stress regulation goes a long way, and may be enough to support and protect the endothelium on its own.

For others, particularly those with genetic vulnerability, long-standing inflammation, or established vascular injury, additional intervention is often needed to further protect and stabilize the lining while healing occurs.

This is not failure.
It is individualized care, matching and supporting the biology.

The endothelium responds to signals, and sometimes it needs more help.

How the Endothelium Gets Damaged (Quietly, Over Time)

Most endothelial injury is not dramatic.

It is cumulative.

A little irritation, day after day.

Blood sugar spikes that repeatedly stress the vessel lining
Frequent insulin surges that disrupt signaling
Oxidative stress from inflammatory and processed foods
Refined sugars and flours that inflame the surface
Oxidized or repeatedly heated oils that impair nitric oxide pathways
Chronic inflammation from autoimmune or metabolic disease
Poor or fragmented sleep that limits nightly vascular repair
Sedentary days stacked into sedentary years
Relentless stress that keeps vessels tense and constricted
Environmental toxins and air pollution adding oxidative burden
Smoking or secondhand smoke exposure
Chronic alcohol excess

None of this causes a heart attack instantly.

But over time, the lining changes.

Nitric oxide production falls.
Vessels stiffen.
Elasticity fades.
Inflammatory cells begin to adhere where they should not.
Exchange between blood and tissue becomes less efficient.

This is what vascular aging actually looks like.

Not wrinkles.
Not gray hair.

But less flexibility, less nitric oxide, less resilience.

Here Is Where the Story Shifts

This is where some people feel discouraged.

They learn that blood vessels age.
That inflammation and blood sugar matter.
That damage accumulates quietly.

And they assume this is simply what time does.

But that is not the full story.

Because the endothelium is not fragile porcelain.

It is remarkably responsive.

It listens.
It adapts.
It repairs.

And when the signals change, it changes with them, often faster than we expect.

Many of the same forces that injure the endothelial lining
are also the very levers we can pull to protect it, calm it, and keep it young.

That is where this becomes empowering.

A Pause Here

If blood vessels are our lifelines, the next question is essential:

How do we protect them?
How do we support flexibility, nitric oxide, and repair, especially as we age or live with inflammation?

Upgrade to continue reading ↓

In the next section, we’ll explore:

• How daily movement acts as direct medicine for the vessel lining

• Why certain foods strain the endothelium, and others nourish it

• How muscle protects blood vessels in ways most people overlook

• How sleep and stress signals directly change vascular tone

• When supplements or medications become protective, not “extra”

• And how to think long-term instead of chasing short-term numbers

Because once you understand how responsive your lifelines truly are…

You start making very different choices.

Read more

This is a concept that comes up frequently.

Someone sits across from me who is clearly doing a lot right.
They work out regularly.
They’re strong.
They walk, lift, cycle, hike, and/or ski. (Which is amazing.)

And yet, their blood pressure is creeping up.

Sometimes it’s mildly elevated.
Sometimes it’s stubbornly high despite great fitness and good habits.
Often, they’re understandably frustrated.

Our conversation usually turns to this question:
What else can they do, differently, to improve arterial health?

A quick note: This is Part 1 of a short series on vascular and endothelial health.

In this article, we’re focusing specifically on movement patterns and arterial stiffness, which is just one of many important contributors to rising blood pressure and cardiovascular risk with age.

In upcoming articles, we’ll explore other critical factors, including inflammation, diet, metabolic health, stress physiology, and endothelial injury and repair. Exercise plays a major role in vascular health, but it’s not the only one. This is just the beginning.

And as always, if you have elevated blood pressure or are new to starting a fitness routine, please work with your healthcare provider.

Fitness does not always equal arterial youth

As we age, arteries naturally stiffen, unless we actively oppose it.

This is a structural, biological process.
It’s not a personal failure.
And it’s not simply a reflection of how fit you are.

Arteries are not rigid pipes. They are living, dynamic tissue, designed to expand with each heartbeat and recoil smoothly afterward. This elasticity cushions blood flow and helps keep pressure lower.

Over time, however, arteries undergo predictable changes:

• Elastin fibers fragment

• Collagen accumulates relative to elastin

• Glycation and oxidative stress increase

• Low-grade inflammation alters vessel tone

• Nitric oxide production declines

• Genetics make some people more susceptible

Hormonal shifts, particularly declining estrogen during midlife, can further accelerate these changes, as estrogen helps support nitric oxide production and arterial flexibility.

The result?

Less stretch.
Less recoil.
Higher pressure.

Even in people who exercise consistently.

Research shows that aerobic fitness and strength training reduce cardiovascular risk and improve endothelial function, but they do not always fully prevent age-related arterial stiffening, especially after midlife.

This is why some very fit people develop:

• Rising systolic blood pressure

• Widening pulse pressure

• “Isolated systolic hypertension”

The heart is strong.
The arteries are stiff.

Why workouts alone may not be enough

Traditional exercise is excellent at improving:

• Cardiac output

• Metabolic health

• Insulin sensitivity

• Resting blood pressure

But large-artery stiffness is influenced by mechanical, autonomic, and hydration-related factors that workouts alone don’t always address.

Preventive cardiologists like Dr. Mark Houston emphasize an important distinction in The Truth About Heart Disease:

“It’s not just how hard you exercise; it’s how consistently and intelligently you move.”

From a vascular standpoint, arteries respond best to regular, rhythmic, moderate stress, which should be part of the workout regimen.

That’s where different habits matter.

What actually supports arterial flexibility

These are not replacements for exercise.
They are additions, and may provide additional benefits.

1. Daily walking (even on workout days)

Gentle, rhythmic movement throughout the day improves:

• Shear stress signaling in blood vessels

• Nitric oxide availability

• Vascular tone regulation

Good old daily walking/movement is one of the most consistently supported interventions for vascular health. It provides frequent, low-grade endothelial stimulation without excessive sympathetic activation.

This aligns with preventive cardiology guidance that movement frequency matters, especially as we age.

More isn’t always harder.
Sometimes it’s just more often.

2. Stretching, yoga, and mobility work

This is one of the most underappreciated findings in vascular research.

Multiple studies show that stretching programs alone, without aerobic training, can:

• Reduce arterial stiffness

• Improve pulse wave velocity

• Lower blood pressure

Likely mechanisms include:

• Reduced sympathetic (fight-or-flight) tone

• Improved nitric oxide signaling

• Decreased vascular smooth muscle tension

From a vascular perspective, flexibility work helps shift the nervous system toward a parasympathetic, vessel-relaxing state.

Flexibility practices don’t just help joints.
They help vessels.

3. Resistance training is beneficial for heart and vascular health

Resistance training is an important part of cardiovascular health. This is well supported in the preventive cardiology literature.

When done properly, strength training:

• Improves blood pressure control

• Enhances insulin sensitivity and metabolic health

• Supports healthy body composition

• Reduces overall cardiovascular risk

Progressive resistance training is associated with lower cardiovascular risk and improved long-term outcomes, especially when paired with good recovery.

What also matters is how strength training is integrated.

Resistance training alone does not appear to fully address age-related arterial stiffness. Large arteries respond best to a combination of mechanical signals, frequent movement, and nervous system balance.

For vascular health, strength training works best when paired with:

• Controlled breathing rather than habitual breath-holding

• Adequate rest and recovery between sessions

• Regular aerobic movement and daily walking/movement

• Mobility or stretching work to support flexibility and parasympathetic tone

When resistance training is part of a balanced program like this, it supports both strong muscles and resilient blood vessels.

Strength training helps the heart.
Movement variety helps the arteries.

Both matter.

4. Avoid chronic dehydration

This is surprisingly common in active older adults.

Mild, ongoing dehydration:

• Increases blood viscosity

• Raises sympathetic nervous system activity

• Increases vascular resistance

• Can falsely elevate blood pressure readings

If blood feels thicker and vessels are less elastic, pressure rises, even if everything else looks “healthy.”

Hydration is not just about kidneys or muscles.
It’s about flow.

5. A note on high-intensity intervals

Brief high-intensity interval training can provide meaningful benefits for cardiovascular fitness, insulin sensitivity, and blood pressure, particularly for people with metabolic risk or limited time.

That said, its effects on arterial stiffness, a marker of vascular flexibility, are less consistent than those seen with lower-intensity, more frequent movement.

High-intensity intervals tend to work best when used as an adjunct: applied intermittently, paired with adequate recovery, and balanced by daily walking, mobility work, hydration, and restorative movement.

For many people, improvements in arterial flexibility appear more reliable with moderate movement performed most days, rather than maximal effort a few times per week.

And a final reminder:

Something is always better than nothing.
Even short walks, light stretching, or brief movement breaks send positive signals to the vascular system to help keep the blood vessels pliable over time.

Why blood pressure often improves when elasticity improves

Arterial stiffness doesn’t just correlate with blood pressure: it drives it, especially systolic pressure.

When arteries can expand and recoil:

• The heart works less hard

• Pressure waves dissipate more smoothly

• Systolic blood pressure often falls

• Pulse pressure narrows

This is why some people see blood pressure improve without changing medications or workout intensity, simply by improving arterial flexibility and recovery.

A brief clinical reminder

Arterial stiffness is common, but it’s not the only reason blood pressure can rise.

If blood pressure is newly elevated or remains elevated despite lifestyle changes, it’s important to consider other contributors, including:

• Sleep apnea

• Kidney disease

• Hormonal factors (thyroid, aldosterone, menopause)

• Medication effects

• Chronic stress or pain

• Genetic predisposition

• Other causes

Lifestyle strategies are foundational, but persistent hypertension always deserves appropriate medical evaluation and treatment. These approaches are meant to support care, not replace it.

My takeaway

Fitness builds strength.
But flexibility keeps the vascular system young.

If blood pressure is creeping up despite good habits, it may not be about doing more; it may be about doing something different.

Strength and cardiovascular fitness matter.
As do regular movement and flexibility work.

Because flexible and resilient arteries matter too.

References

1. Mitchell GF, Hwang SJ, Vasan RS, et al. Arterial stiffness and cardiovascular events: the Framingham Heart Study. Hypertension. 2010.

2. Vlachopoulos C, Aznaouridis K, Stefanadis C. Prediction of cardiovascular events and all-cause mortality with arterial stiffness: a systematic review and meta-analysis. European Heart Journal. 2010.

3. Ashor AW, Lara J, Siervo M, et al. Exercise modalities and endothelial function: a systematic review and dose–response meta-analysis of randomized controlled trials. Hypertension. 2014.

4. Montero D, Vinet A, Roberts CK. Effect of aerobic exercise training on arterial stiffness in obese populations: a systematic review and meta-analysis. Sports Medicine. 2015.

5. Thijssen DHJ, Maiorana AJ, O’Driscoll G, et al. Impact of inactivity and exercise on the vasculature in humans. Hypertension. 2011.

6. Yamato Y, Hasegawa N, Sato K, et al. Stretching exercises improve vascular endothelial function and arterial stiffness. The Journal of Physiology. 2016.

7. Nishiwaki M, Yonemura H, Kurobe K, et al. Effects of static stretching on arterial stiffness and blood pressure in middle-aged men.
   American Journal of Physiology – Heart and Circulatory Physiology. 2015.

8. Wong A, Figueroa A. Eight weeks of stretching training reduces aortic wave reflection magnitude and blood pressure in obese postmenopausal women. Journal of Hypertension. 2018.

9. Watso, JC, Farquhar, JB. Hydration Status and Cardiovascular Function, Nutrients, 2019.

10. Safar ME, Levy BI, Struijker-Boudier H. Current perspectives on arterial stiffness and pulse pressure in hypertension and cardiovascular diseases. Hypertension. 2003.

11. Houston MC. The Truth About Heart Disease. 2023.