The Human Gut Microbiome: Our Inner Ecosystem

Our bodies are home to trillions of microbes that play a vital role in our health. I never learned about this microbiome in school – instead I was taught that microbes were dangerous and we needed to kill them with disinfectants and antibiotics. But in the last 10-15 years, scientists have discovered that these microbes are not only harmless, but essential for our wellbeing.

In this article, I’ll explain what the human microbiome is, why it’s so important for health, and how you can optimize your gut microbiome.

What is the Microbiome?

The microbiome refers to the entire community of microbes that live in and on our bodies. This includes bacteria, viruses, fungi and other organisms.

You can think of your microbiome as a complex ecosystem, similar to a rainforest or a coral reef. There are thousands of different species that interact and depend on each other for survival.

The human body contains around 40 trillion microbes. That’s about the same number as human cells! So in a way, we’re only 50% human – the rest is our microbiome.

The gut microbiome is the most heavily colonized by microbes. It contains over 1000 different species and trillions of microbes. Many people mistakenly think of the gut as an empty passageway for food. But it’s actually teeming with microbial life that’s absolutely essential for our health.

A Long Evolutionary Relationship

Humans and microbes have evolved together over millions of years in a symbiotic relationship. We provide them with a place to live, and in return they help us digest our food, regulate immunity, produce vitamins and perform other vital tasks.

In fact, the first human cells likely evolved from the fusion of microbial cells billions of years ago. So you could say we originated from microbes!

Throughout our evolution, microbes have allowed humans to adapt and thrive in different environments around the world. Each geographical location has its own ecosystem of microbes. When humans migrated to new areas, we acquired the microbes needed to digest the local foods.

So the microbiome gave us a flexible digestive capacity, unlike anything in our own DNA. This allowed us to maximize nutrition from a wide variety of diets.

The microbiome is an integral part of what makes us human. We’ve relied on these microbes for our entire existence. Attempts to totally eliminate them have thrown off the balance and led to unintended health consequences.

Why the Microbiome Matters

Research over the past decade has revealed just how profoundly the microbiome affects our health. Gut microbes influence digestion, immunity, inflammation, hormone balance, metabolism, and even mental health.

Here’s a brief look at some of the ways gut bacteria impact our wellbeing:

• Digestion – Gut microbes break down indigestible fibers, synthesize vitamins, and allow us to extract nutrients from food we couldn’t digest on our own.
• Immunity – Beneficial gut bacteria strengthen the gut barrier and regulate immune cells to prevent infection and autoimmune disease.
• Inflammation – The microbiome helps control levels of inflammation in the body and protect against chronic inflammation.
• Hormones & Neurotransmitters – Gut microbes regulate hormones including serotonin, dopamine and GABA that control our mood, appetite and sleep.
• Metabolism – Gut bacteria play an important role in controlling blood sugar, cholesterol, weight gain and metabolic health.
• Disease Protection – A healthy microbiome protects against diabetes, heart disease, cancer, obesity, depression, anxiety, autism and neurodegenerative disease.
• Genetic Expression – Microbes interact with our DNA, switching genes on or off that affect our health and disease risk.

This just scratches the surface of the microbiome’s diverse effects throughout the body. Scientists are discovering new connections every day. It’s clear these bacteria are far more than just harmless hitchhikers. They are indispensable for optimal health.

Optimizing Your Gut Microbiome

The composition of your gut microbiome is the result of lifelong interactions between your genes, diet, lifestyle, medication use and other exposures.

Just like any ecosystem, the gut microbiome thrives on balance and diversity. A healthy microbiome contains lots of different species that keep each other in check.

Unfortunately, today’s highly-processed diet lacks the fiber needed to nourish gut bacteria. Overuse of antibiotics also depletes the microbiome. This can allow harmful bacteria to dominate, creating inflammation and disease.

The good news is you’re not stuck with the microbiome you have! There are many effective ways to improve gut health, including:

Eat More Fiber-Rich Plant Foods

Fiber is the preferred fuel source for beneficial gut bacteria. Aim to eat 30 different plant foods per week. Emphasize whole fruits, vegetables, nuts, seeds, legumes and whole grains.

Eat Polyphenol-Rich Foods

Polyphenols are plant compounds that feed good bacteria. Enjoy plenty of deeply colored fruits and vegetables, coffee, dark chocolate, herbs and spices.

Consume Fermented Foods

Fermented foods like yogurt, kefir, kimchi, sauerkraut and kombucha contain live microbes that can benefit your microbiome when consumed regularly.

Avoid Ultra-Processed Foods

Heavily processed foods feed harmful bacteria and contribute to a loss of diversity. Limit snacks, sweets, refined carbs and fried foods.

Exercise Regularly

Exercise improves gut motility and microbial diversity. Aim for 30-60 minutes per day of moderate activity like walking.

Disrupted sleep alters gut microbes in ways that promote inflammation and metabolic disease. Stick to regular bed and wake times.

Manage Stress

Chronic stress harms beneficial bacteria. Make time to relax and participate in stress-relieving activities each day.

There are no shortcuts when it comes to the microbiome. Probiotic supplements may provide a helpful boost, but they can’t replace a healthy lifestyle. Focus on shaping your diet, exercise, sleep and stress to cultivate a diverse gut microbiome.

The Microbiome and Personalized Nutrition

One of the most exciting areas of microbiome research is using it to understand individual responses to food. We are all biologically unique, so there is no one ideal diet for everyone.

New technology allows us to map each person’s gut microbiome and see how it processes nutrients from different foods. For example, you can test your blood sugar response to see which carbohydrates you tolerate best.

You can also see which foods act as “gut boosters” that nourish the beneficial species of bacteria in your microbiome. This data can help you shape your diet for optimal health and weight.

Your Genes, Microbiome and Diet

This personalized approach represents the future of nutrition. By better understanding the interplay between your genes, microbiome and diet, you can eat in a way that’s tailored to your unique biology.

The microbiome is one of the most fascinating new frontiers in science. After ignoring gut bacteria for decades, we now realize they are integral to our health and survival.

A healthy lifestyle supports a flourishing gut microbiome that in turn improves every aspect of your wellbeing. I hope this article has given you a new appreciation for the microscopic ecosystems inside us and how we can care for them!