In what feels like several lifetimes ago, I was a resident in internal medicine at Lincoln Hospital in the Bronx in the mid 80’s. Back then, our training was very much a product of conventional Western medical thinking. In the U.S., the standard protocol was:  diagnose, prescribe, manage disease, repeat. Specialists guarded their own turf but the “whole person” usually got a bit lost in the shuffle.

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Fortunately, I was exposed to different healing techniques as a young med student working with traditional healers in my native South Africa and then later heavily influenced by studying multiple ancient wellness traditions, making use of acupuncture and herbs from traditional Chinese medicine and medicinal herbs from the European herbal tradition, Indian ayurveda and beyond. Over the years, I was able to carve my own path, integrating the wisdom of both traditional and modern approaches so patients could heal and thrive. But recently I’ve come to appreciate how much one of the most exciting conceptual breakthroughs in modern medicine -- the crucial role the gut, and specifically, the  gut microbiome, plays in overall health -- owes to the prescience of ancient Western thinkers.

Be it ancient wisdom or modern science, gut health is a timeless essential.

Hippocrates (460–370 BCE), the Greek physician often hailed as the “father of Western medicine,” is best known for his declaration primum non nocere, or, “First, do no harm”. Whether he uttered those exact words is uncertain, but their spirit has anchored medical ethics through the centuries. Another saying attributed to him, ‘All disease begins in the gut,’ feels especially pertinent today. Again, the exact phrase may be apocryphal, but the underlying insight lives in his teachings.

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As modern science expands our understanding of how trillions of microbes in our intestines influence our immunity, metabolism, mood, and aging, I see Hippocrates’ intuition in a new and more profound light. Revisiting that ancient medical tradition helps us think about health and longevity in a more integrative and holistic way, ideally helping us to enhance both.

Thinking of the body as a symphony, not a machine.

One of the most notable features of modern medicine is how reductionist it is. The assumption (often implicit) is: break the body into parts and study each in isolation. Cardiologists study hearts; neurologists focus on brains; gastroenterologists tend to guts. While there’s no denying this method has penetrated to incredible depth in each field, it’s also obscured how the parts related to the whole, how interconnected they are. 

When your gut microbiome flourishes, so do you.

The surge in microbiome research is leading us back toward a more connected view. A flourishing, balanced gut microbiome helps regulate inflammation, powers up immunity, and sends important signals to the brain. When that balance is out of whack, problematic symptoms can show up almost anywhere, making themselves known, for example, in the form of allergies, irritated skin, joint pains, dipping energy levels, mood problems, etc.

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The Hippocratic model described health as a harmony of the four humors (blood, phlegm, yellow bile, black bile). Though the humoral model is scientifically obsolete, its core principle, that health emerges from dynamic balance across systems, resonates strongly with contemporary microbiome science.

Balance and imbalance – think microbes over ‘humors.’

In the Hippocratic blueprint, health was in order when the humors were in equilibrium. In our age, we talk about equilibrium across microbial species, especially in the colon. When beneficial bacteria dominate, they can more effectively ferment dietary plant fiber into short-chain fatty acids (SCFAs), compounds that nourish and fortify the gut lining, reducing inflammation and supporting immune balance.

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But, when “bad” bacteria overpopulate and gain the upper hand, the effects of this imbalance, or ‘dysbiosis’, ripple outward. Within the gut, problems like irritable bowel syndrome, bloating, inflammatory bowel diseases can wreak havoc. Or, the lining of the gut (which is only one cell thick for a large section), can develop microscopic holes, so-called  “leaky gut,” allowing toxins or undigested food particles to escape the gut and seep into the bloodstream, triggering systemic inflammation. There’s also the specter of compromised immunity (70% of your immune system is in or around the gut), where a weakened microbiome fails to teach the immune system to distinguish harmless substances (like certain food proteins) from threats, prompting excessive inflammatory responses, manifesting as rashes, allergies, fatigue, or GI upset. 

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The ancient Greeks observed symptoms like constipation, diarrhea, or gas and reasoned that “trapped waste” was rotting inside the body. Ironically, we know now that fermentation of dietary fiber (or rot, if you like) by beneficial microbes is actually a constructive, health-affirming process. A recent review emphasizes how dietary patterns (prebiotics, fermented foods, bioactive plant compounds) enhance microbiome diversity and stability – and overall health too boot. That’s no small thing.

From Hippocrates to modern practice.

Over the past seventy-five years or so, Western medicine took a major wrong turn. It became so proficient at developing drugs to combat illness (with spectacular success against infectious disease and much less success against chronic “diseases of aging”), that it often ignored the lifestyle basics – diet, exercise, stress management – which were and still are our best protection against getting sick in the first place. Not a mistake the ancient Greeks made – they simply didn’t have many effective therapies to work with once disease took root. Consequently, they became close students of how diet, exercise and adequate rest promoted and maintained good health, which to them, meant a healthful balance of the four humors. Modern medicine has only recently caught up.

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Now we stress the importance of a clean diet – plenty of fiber-loaded plant foods (think non-starchy veggies like greens) and anti-inflammatory good fats like the omega 3s, both for good gut health and good overall health. Moving the body as often as possible is key as well. Exercise, as long as it’s not excessive, lowers overall systemic inflammation, is good for the gut and for everything else, ditto good sleep and sensible stress management. It’s a winning health and longevity combo for sure.

Minding the gut-brain axis.

The Hippocratic tradition ties everything together with its four humors, very much including the brain. Good digestion and elimination were seen as foundational for good mental health. That’s an idea that might have seemed primitive to Western physicians a generation or two ago. But using the tools of modern science, we can now map out what the Greeks were getting at.

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We understand the importance of the gut and the brain being connected by the largest nerve in the body, the vagus nerve. The stressed-out brain, by pushing up the production of cortisol, can inflame the gut and disrupt the healthful balance of bacteria in the microbiome. And an out-of-balance microbiome can throw off the production of feel-good neurochemicals like serotonin and dopamine, and an anxiety-lowering one, GABA, inside the gut. Therefore, it makes sense that we often can help treat brain-related conditions like fatigue, brain fog and depression by attending to the gut.

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While we are still far from having worked the precise mechanisms by which the gut and its microbiome impact mental health, psychiatrists have noted for decades that gut issues often precede or coincide with the arrival of an emotional disorder. The ancients wouldn’t have been surprised.  

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BOTTOM LINE: The parallels between ancient medicine and modern microbiome science are striking -- balance, interdependence, prevention. Ancient Western healers spoke of humors; today; we talk about microbes. But the spirit is the same. The message then and now is: when we see ourselves as ecosystems, not machines, we become better stewards of health. Modern research confirms what ancient wisdom has known for millennia: your gut is foundational for your health. Supporting its microbial balance is one of the most powerful steps you can take— to protect your immunity, your cognition, and your longevity.