What constitutes a 'healthy' diet?

The gut microbiome—a complex community of up to 100 trillion microbes—has a changing composition, influenced by our life stage, diet, medications, environment, and other factors.

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 up to 100 trillion microbes in the gut, and maintaining the relative balance in this ecosystem is important for our health.

What is the gut microbiome?

The gut microbiome is a microscopic ecosystem that runs off the work of microbes in the digestive tract. These workers make getting energy from food possible. What and how that energy manifests depends on what building blocks these microbes have to work with, meaning their composition and functions are strongly influenced by diet. Gut microbes have their own genes, which affect how a person's genes act.

Exercise causes diet-independent changes in the gut microbiome.

In 2026, University of Cambridge researchers reported that a group of gut bacteria called CAG-170 may be a key marker of good health, occurring far more often in healthy individuals and less commonly in people with chronic diseases.

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.

Some animals, including certain tropical ants, have little or no microbial populations in their gut, upending the idea that all animals rely on this ecosystem to help maintain their health and proper functioning.

Trillions of bacteria, viruses, fungi, protists, and archaea live in our guts, producing a wide range of molecules, hormones, and more—underscoring the immune system's pivotal role in the microbiota-gut-brain axis.

How understanding a balanced diet can help you make good food choices

Eating a balanced diet—which includes a variety of foods from all food groups—is important for optimal health. It is also recommended to avoid ultra-processed foods, such as frozen meals, fast foods, soda, and flavored yogurt. The simplest way...

Gut bacteria are evolving and can acquire as many as 100 new genes per year, on average.

A technical review of what researchers know about the gut microbiome

This overview from the National Institutes of Health provides a deeper (but still accessible) look at the different bacteria in the gut, how the microbiome develops through life, its purpose, and more.

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…

Researchers are investigating how altering the gut microbiome may influence the development of rheumatoid arthritis, which is an autoimmune disease.

The gut microbiome may play a major role in autoimmune disease and symptom flare-ups

Certain unhealthy foods can promote gut bacterial growth and inflammation in the lining of the gut, potentially disrupting its lining—leading to a leaky gut that may allow pathogens to dribble out into the bloodstream, fueling further inflammation that can both cause disease flare-ups and set the stage for future disease development.

Researchers generally group gut bacteria into six different categories, with varying amounts of these microbes residing in different parts of the digestive tract.

Gut microbiome rewrites may help reduce allergies

Researchers are investigating different strategies to determine if one day they could give people a combination of gut microbes to set them up for fewer allergies. In animal research, scientists have already prevented severe allergic responses in allergy-prone mice—supplying them with gut microbes from healthy, non-allergic human babies.

There's no specific anti-inflammatory diet, but certain foods increase the chance of inflammation

Research suggests humans can reduce inflammation by limiting foods that are already known to be unhealthy for the human body—because they alter gut bacteria and stress the immune system—such as highly-processed foods, deep fried foods, sugary drinks, trans fats, red meats, and foods made with white flour. Foods that help the body include fatty fish such as salmon, legumes, fruits, and vegetables.

The evolution of the human diet

Could eating like our ancestors make us healthier? One estimate suggests prehistoric hunter-gatherer communities obtained 75% of their calories from meat and fish.

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.

Should you eat an all-meat diet?

The carnivore diet is reportedly a way of eating inherited from human ancestors, a tale that has roots in anthropology's early days. This article explores the all-meat diet's ancestral claims and what happens if you cut vegetables and fruits from...

Remember: Not all fats are bad for you

Contrary to past dietary advice promoting low-fat diets, newer research shows that certain types of fats are both necessary and healthy. It all comes down to the type of fat you eat. Focus on getting "good" unsaturated fats from sources like nuts,...

Specific gut microbiome 'fingerprints' are associated with cancer recurrence, with up to 94% accuracy.

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.

Food companies are exploring 'GLP-1 friendly' diet labels

Producers of foods like Healthy Choice frozen meals are placing "GLP-1 friendly" labels on their food, but there's no regulation about what that label means. Nutritionists say that GLP-1s can help reduce appetite, but healthy, balanced diets are a necessary complement to the medications. Data shows that about half of GLP-1 users quit these medications within a year and then rapidly regain weight, underscoring the importance of also prioritizing healthy eating.

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.

Blue zone cooking—a concept that journalist Dan Buettner developed from his reporting on centenarian populations—emphasizes cooking with simple, fresh ingredients and echoes themes of the well-known Mediterranean diet.

The gut microbiome's community of viruses is collectively known as the virome, but most of its viruses remain unidentified.

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.)

See how the gut and the brain communicate through a bundle of nerves running from the brain to the digestive tract, serving as both a physical and chemical link.

The term 'superfood' is a marketing construct with no scientific or medical definition

Encompassing at least 136 plants and animals, the concept has been criticized by nutritionists for its scientific value, which has been exploited by the wellness industry for profit. Although the label has encouraged the consumption of fruits and vegetables, food variety and minimal processing remain key to a healthy diet.

Gut microbiome experiments involving transfers of gut microbes from depressed people to rodents indicate that the rodents may then display depression-like symptoms.

Learn how colorectal cancer is linked to the American diet and chronic inflammation

A University of South Carolina colon cancer researcher offers insights from his own research and notes that more exercise, social support, and eating fruits, vegetables, legumes, and foods like fish and olive oil—often called the Mediterranean diet—are associated with better health—and could improve our colons.

A 19th-century Protestant minister in Germany encouraged 'natural eating,' creating a precursor to the natural food movement.

Ultraprocessed foods include preservatives, dyes, sweeteners, and more

Processed foods are those that have been altered from their original state, which includes numerous processes that we consider natural, such as cooking or salting. Ultraprocessed foods contain at least one item that wouldn’t be found in a kitchen, like hydrogenated oils or high-fructose corn syrup. It’s estimated that nearly 75% of all foods consumed in the US are ultraprocessed, though that doesn’t mean that all of them are unhealthy. In fact, some, such as prepackaged whole wheat bread and soy milk, are recognized for their health benefits.

Bacteria in our intestine influence the brain via the gut-brain axis.

Western babies often lack a gut microbe common elsewhere.

A quarter of Gen Z eats organic food

A 2025 YouGov poll found that 25% of Gen Z US adults eat organic food, while 10% say they follow a whole-foods diet, meaning they seek out foods that are minimally processed.

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.

Some dementia cases may be linked to treatable microorganism infections in the brain.

What should you eat to help the climate?

Climate change is impacted by what we eat and what we don't eat. Did you know, for instance, that livestock accounts for 14.5 percent of the world’s greenhouse gases each year? Eating less meat and dairy and more protein-rich plants like beans,...

What’s the best way to reduce climate impact of food?

Food is a big part of everyone’s carbon footprint, and it’s important to understand the impact of our personal food consumption. Individual food choices can emit as many greenhouse gases as personal electricity use. Plant-based diets generally...

Ultra-processed foods are made to maximize cravings and encourage overeating

Often disguised as healthy options like granola bars and low-fat yogurt, these foods silently fuel chronic diseases, despite dominating diets. Reviewing labels for ingredients like stabilizers and emulsifiers can serve as indicators to help identify these products.

How healthy is lab-grown meat?

While meat-less meat options like Beyond and Impossible burgers are known for being the environmentally-friendly alternative to real meat, it’s important to also consider their impact on human health. Health benefits of these meat alternatives...

Artificial sweeteners may disrupt gut health, throwing off the balance of beneficial bacteria in the gut and shifting the composition of the microbiome.

Probiotics, which are living bacteria and yeasts, are not recommended for most patients.

How meal timing factors into health outcomes

The world is trending toward weight gain, a development that comes with a corresponding rise in risk for health conditions, including diabetes and heart disease. This article explores how meal timing has become a factor in nutrition and weight maintenance.

Learn what the best foods are to survive on a limited diet

The human body can naturally synthesize 11 of the 20 amino acids needed to build the critical proteins required for function, but the nine missing ones can all be obtained from white potatoes. A bit of oatmeal can provide the molybdenum needed to process sulfites from potatoes, while other key vitamins and nutrients can be acquired from avocados, berries, milk, beans, and spinach.

Organic food might be greener, but it’s not better for you

Weighing in on the ongoing debate surrounding organic versus “regular” foods, health experts explain whether organic foods offer significant health benefits. Studies suggest that organic foods have little additional nutritional value compared to...

Health food broke into the mainstream by the 1980s

A 1984 New York Times story noted that Americans were eating less red meat than a decade prior, and that, in general, the country was “talking, thinking and worrying about what they eat to a degree unique in the nation's history.” The feature then details foods that were then considered bizarre: whole-grain muffins, hummus, and a variety of vegetarian dishes. (Some readers may experience a paywall.)