What is the gut microbiome?

How the microbiome affects your health

The gut microbiome is so influential to overall human health that some researchers consider it a separate organ. Its conditions, influenced by environmental and lifestyle factors such as medication and exercise, contribute to immunity, metabolism, inflammation, medical treatment efficacy, brain development and function, and the development of disorders and diseases, including asthma, depression, inflammatory bowel disease, and Alzheimer's.

There are between 10 and 100 trillion bacteria in the gut

The composition of our microbiome is essential to overall health. Anything that disrupts the balance of the trillions of bacteria may be harmful—even treatments meant to fight infection, like antibiotics.

What is a microbiome (and why are they important)?

Jump to: What is the microbiome? How microbiota benefit the body The role of probiotics Can diet affect one’s microbiota? Future areas of research What is the microbiome? Picture a bustling city on…

Chemicals from the gut have complex interactions with the rest of the body

Trillions of bacteria live in our guts, producing a wide range of molecules, hormones, and more. This review underscores the immune system’s pivotal role in the microbiota–gut–brain axis. Gut microbes influence immune cells and metabolites, which in turn modulate neurodevelopment, neural signaling, mood, and neuroinflammation—highlighting immune pathways as central mediators in gut‑brain communication.

How to maintain a healthy gut

Approximately 40 trillion microbes reside in the human gut, forming a unique microbiome, containing hundreds of millions of neurons in what is often called a "mini-brain". A healthy gut is characterized by an effective mucus-lined barrier that prevents unwanted substances from entering the bloodstream. So how do you attain such an ideal gut? This guide outlines a healthy approach to protecting your gut.

The gut microbiome, explained

This video from 1440 takes a high-level look at what populates the gut microbiome, its purpose, how it affects our health, and much more.

Listen to how the gut microbiome influences your emotions

The gut-microbiome connection may involve the enteric nervous system, a collection of hundreds of millions of neurons throughout the gut that transmit signals up the vagus nerve to the brain.

What is the gut virome?

The gut microbiome's community of viruses is collectively known as the virome. It has been found to affect immune system development—important to the gut-brain axis—and has been implicated in the development of inflammatory bowel disease and Type 2 diabetes. As of early 2023, less than half of the viral sequences in the gut had been identified. Further study is needed to understand the virome's influence and therapeutic potential.

Some animals have little or no bacterial populations in their gut

Gut microbiomes are essential to human health, but many animals have a much smaller, transient, or even nonexistent microbiome. The discoveries have advanced our understanding of the evolution of the human microbiome.

What happens when the gut microbiome is out of whack?

An imbalance in gut microbiome flora can lead to a condition known as dysbiosis. This condition is typically characterized by a drop in microbiota diversity and an increase in harmful unicellular and acellular organisms, such as viruses, that can negatively impact the host's immune system and overall health. Genetics, infections, dietary choices, antibiotics, food additives, artificial sweeteners, and other lifestyle and environmental factors can cause dysbiosis.

What's next for gut microbiome science?

A Stanford microbiologist explores what we don't yet know about the gut microbiome—such as whether we can engineer the bacterial species within it—and the current scientific advances in the field.

What constitutes a 'healthy' diet?

A natural diet, typically high in plant-based foods and low in processed foods, appears to be the main contributor to a healthy, diverse gut microbiome.

Researchers generally group gut bacteria into six different categories

The trillions of bacteria in the gut microbiome can be grouped into six categories: firmicutes, actinomycetota, pseudomonadota, fusobacteriota, bacteroides, and a broad miscellaneous category. The functions of each are complex but range from breaking down food and producing vitamins to fighting pathogens.

Can the gut microbiome drive addiction?

New research suggests an imbalance of gut microorganisms may influence the likelihood of addiction and addictive behaviors by increasing the severity of withdrawal symptoms, triggering brain inflammation in regions of impulse control, and more.

How the gut microbiome can affect heatstroke risk

Some research suggests that our gut microbiome influences our risk of exertional heatstroke. If exercise boosts our body temperatures to unsafe levels, increasing gut permeability, that can cause a "leaky" gut—allowing bacteria and other gut microbes to leak into the bloodstream and potentially trigger endotoxemia, a potentially life-threatening inflammatory response that can occur with heat exhaustion and heatstroke.

The reason some people love exercise may be because of their microbiome

Certain gut microbes in mice trigger dopamine release and drive motivation to exercise more. Scientists are investigating whether humans carry similar microbial patterns that influence our natural inclination towards movement, exploring how unseen microbial ecosystems may shape mammalian fitness behavior and reinforce innate reward pathways. (Some users may experience a paywall.)

Microbes are essential to creating the many varieties of cheese, influencing texture and taste

Microbes break down proteins and fats and produce compounds with distinct tastes. These microbes can include bacteria (like the one used to give Swiss its trademark holes), molds (like the ones that give blue cheese its distinctive veining), and countless other tiny organisms.

Visualize the different parts of the digestive tract

The digestive tract, also known as the gastrointestinal tract, runs from our mouths to rear ends. Its major components include the esphoagus, stomach, intestines, colon, and more.

Are probiotics a scam?

Probiotics are microbes meant to benefit the gut microbiome's health when consumed. This internal cityscape is packed with thousands of species of microbes whose roles and impacts have yet to be untangled. The odds are low that the probiotics have the effects they're marketed to have, and most of the gut helpers on grocery shelves have little to no evidence of impacting gut microbiome health.

How metabolism, when cells convert molecules into energy, works

Metabolism is when a cell’s internal network of chemical reactions breaks down food molecules and transforms them into pieces of the cell itself. Sometimes, cells build replacements for worn-out parts. Other times, they build energy molecules that power the cell’s activities.

Where do genes come from?

There are many more genes on Earth today than when microbial life first spawned on the planet about four billion years ago. Many of these newer genes grew from genetic mutations, misprints that slowly drift from the original blueprint via cellular division. If these mutations drift far enough, they can establish a new family of genes, though this process can take well over a million years.

What exactly is a GMO?

A GMO, or genetically modified organism, is an organism whose DNA has been altered for specific improvement such as longer shelf life, disease resistance, or enhanced nutrition—which can benefit both farmers and consumers. While humans have used...

The gig economy is a labor market in which workers earn money through on-demand jobs

These “gigs” are often temporary or flexible tasks, such as driving for Uber. Colloquially, the term “gig economy” usually refers to people doing jobs where they connect with people who request their services through an app.

Visualizing the built world compared to the natural world

In the last century, humans have covered the Earth in 1,300 metric gigatons of built material, known as technomass. That amount is more than the Earth's entire biomass at 1,100 GT, which includes all living organisms. To get a sense of the scale of this comparison, click through this striking, simple visualization showcasing the various organisms comprising biomass as well as the materials making up the technomass.

What is gravity made of?

Our world at very small scales is governed by quantum mechanics, in which forces and energy come in discrete packets. At large scales, our world is governed by gravity, which moves the planets and stars and can create waves in spacetime. To merge...

Coral reefs get their colors from zooxanthellae—microorganisms that line corals' digestive tracts and provide them with sugars in exchange for a home within this protective tissue.

Visualize how CRISPR-Cas9—a type of immune system used by single-celled organisms to attack invasive viruses—targets and makes precise changes to a gene's DNA.

Memecoins are a type of cryptocurrency—a form of digital currency with a wide variety of uses—created around popular 'memes,' or viral internet jokes.

Hookworm infection, though risky, may help fight certain autoimmune conditions by tamping down the immune system's inflammatory response.

Explore the history, structure, and species of Australia's Great Barrier Reef with this interactive journey narrated by Sir David Attenborough.

Learn how your body is, scientifically, like a firework with its own slow, controlled burn.

Tattoos remain visible on your skin thanks to immune cells called macrophages

While atoms are normally made of protons, neutrons, and electrons, exotic ones have been built with antimatter—alternate versions of normal matter that live for fractions of a second and are about a billion times as rare.

Studies suggest when you sleep is as important as how much you get, and syncing with your circadian rhythms may lead to less fatigue and improved long-term health outcomes

The use of fungi to detoxify land and water—a process known as mycoremediation—has been used to clean up natural resources affected by the 2025 California wildfires.

Bone marrow (soft tissue found inside certain bones) generates roughly 500 billion new blood cells each day

Scientists can determine Earth's past climate conditions by analyzing air trapped in microscopic bubbles within ice cores—columns of compressed snow layers that build up over hundreds of thousands of years.

The syncytiotrophoblast is the outer layer of the placenta and the largest human cell, spanning an area about twice that of a king-sized bedsheet.

Explore our favorite visualization of the immense scale of space, from an astronaut to the size of the observable universe

The American cockroach is actually from Africa, an apparent hitchhiker aboard ships carrying enslaved people, with evidence suggesting the bug may have arrived in the New World as early as the 1600s.

How Amazon operates a 'flywheel' business model, a self-reinforcing cycle that drives continuous growth

Ebola is a filovirus, meaning it resembles a thread under a microscope, though it sometimes twists and can resemble a bowl of spaghetti.

The price of gas is a composite made up of several different factors, with the federal gas tax making up less than 20% of what drivers pay at the pump.

Discover the catastrophic consequences of a failure of the US electrical grid—something that is more likely than many Americans think.

The Brothers Grimm were lawyers before they were storytellers, but became interested in fairy tales as they began investigating how rules and customs had been passed down through cultures.

In 1963, a basement renovation in Turkey revealed a passageway to a hidden, multilevel underground city that once housed as many as 20,000 people

Gerrymandering works through two techniques: cracking opposing voters across districts to dilute their power, and packing them into a few to waste their votes in lopsided majorities.

Some researchers have labeled nomophobia, the fear of being without your phone, as 'the phobia of the 21st century.'

The first steps to rebuilding your credit score include getting to know exactly what's on your credit report and figuring out how far you are from the '700 club,' or 'good score' range.

A small portion of The Winstons' 'Amen, Brother,' an obscure '60s gospel record, is the basis for thousands of hip-hop tracks, making it one of the most sampled records ever that's informally known as 'the Amen break.'