What constitutes a 'healthy' diet?

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's role in chronic diseases

Research shows that the microbial makeup of one's gut microbiome is associated with chronic diseases ranging from asthma to schizophrenia. Understanding these associations may reveal new ways to prevent or treat chronic diseases. In the meantime, nutritional changes—such as including more dietary fiber and unsaturated fat—appear to be the "most obvious, noninvasive, and immediate" way to alter the gut's microbiota makeup and functions.

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.

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.

Exercise causes diet-independent changes in the gut microbiome

Cardiovascular exercise has been found to boost the gut's population of beneficial bacteria, and exercise overall decreases the likelihood of developing a "leaky gut," a condition in which a porous gut lining allows bacteria to leak into the bloodstream and cause inflammation.

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...

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.

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.

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.

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,...

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.

Eduard Baltzer encouraged 'natural eating' in the 1860s

Historian Corinna Treitel credits the Protestant minister with inventing the concept of “natural eating” in Nordhausen, Germany, in the 19th century. Baltzer believed that people were consuming excessive amounts of schnapps, sugar, and meat, and that this behavior was having a detrimental impact on their lives. He encouraged a diet mostly of fruits and vegetables, though he was not opposed to food grown with artificial fertilizers.

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.

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.

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.

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,...

Western babies often are missing a key gut microbe common elsewhere

Studies show infants in Europe and North America often lack Bifidobacterium infantis, a microbe widespread in babies in Africa and South Asia that helps digest breast milk and train the immune system. Researchers link the gap to antibiotics, formula use, and sanitized spaces.

Over the years, the USDA has changed its definitions of healthy eating

The US Department of Agriculture began offering eating advice in 1894 and has updated its guidance as both science and politics have evolved. In the early 20th century, its guidance emphasized recommended minimum servings of important foods; in later decades, its visual guides became more nuanced, illustrating the composition of a healthy diet and encouraging exercise.

More than 2 billion people across the globe include bugs in their diets

Entomophagy is the practice of eating insects. It has been around for millennia. Bugs are nutritious and, in some places, considered a delicacy.

Collagen supplements typically come from animal sources like fish, pigs, or cattle

Eating collagen-rich foods won't lead to more collagen in the body because your digestive system breaks down consumed collagen into amino acids. Instead, eating a healthy diet of proteins and greens helps your body to produce collagen. Collagen supplements derived from animal skin and bones are typically sold in a prebroken-down peptide formulation called hydrolyzed collagen so they can be absorbed through the gut into the bloodstream.

How the buildings you occupy may affect your brain health

Beautiful spaces filled with light and natural motifs aren't just aesthetic, but likely key to your health. Researchers had study participants view photographs of two distinct buildings, one designed with more natural elements while the other featured more abstract shapes and lines. Using electroencephalograph readings of each participant, they discovered participants had less brain inflammation while viewing the "biophilic," or natural, architecture. Learn more about the interdisciplinary framework of so-called neuroarchitecture here.

Fungi can cause disease, but they’re also our planet’s key decomposers

Fungi are their own taxonomic kingdom separate from flora and fauna, acting as the key decomposers and nutrient recyclers for our planet. Watch this video to understand the diverse types of fungi and the stages of the fungal life cycle. This video illustrates how fungi species may spread, eat nematode worms, damage nearby plants, and much more.

Vitamins are micronutrients human bodies need but don't naturally produce

Each vitamin is found in specific portions of a normal human diet and supports normal human functioning in distinct ways. Vitamin A is found in red meat, carrots, and potatoes and supports vision and skin health, while Vitamin D (common in fish and mushrooms) helps absorb calcium. See sources and uses of each vitamin with this chart.

Health span: The number of years one is active and disease-free

As scientific advances continue to extend the average human lifespan, many are now turning their attention toward extending "health span." The ultimate goal would be to extend one's health span to match one's lifespan, which would necessitate a shift in focus toward the pursuit of healthy aging. (Some users may experience a paywall.)

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

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

Read a deep dive on the 'all-purpose healing' peptide BPC-157.

At the beginning of the 20th century, a group of young men ate standard American food—replete with food additives like borax and formaldehyde—as part of government research to better understand food safety.

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.

Alzheimer's can lead to brain shrinkage, with an average of around 2% of volume reduction per year

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.

Poison ivy is in the same family as mangoes, cashews, and pistachios—and they all produce oily urushiol in their raw, unprocessed state—but they are typically prepared in ways to avoid causing human discomfort.

Larger animals like giraffes, elephants, and blue whales have developed a unique defense against cancer, a phenomenon known as Peto's Paradox

Explore an interactive map built from more than 100,000 survey responses on where people find joy in their lives

Scientists have struggled to pin down Ebola's natural reservoir species for decades, but the available evidence suggests that it's very likely fruit and insect-eating bats found in Africa.

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

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

Fast-casual restaurant Chili's is experiencing a resurgence, with its parent company recently reporting a nearly 32% increase in sales, thanks to passionate Gen Z fans on TikTok.

Astronauts have repaired genetic damage in space using CRISPR—a molecular tool that can make precise changes to DNA and is used in single-celled organisms to attack invasive viruses.

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.

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 Nasdaq's 'Magnificent 7' companies are responsible for roughly 40% of the Nasdaq 100 index's gains, while the remaining 93 companies account for the other 60%.

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.

About 12.5% of US adults experience a phobia in their lifetime, a diagnosis that hinges on the intense fear interfering with daily life and persisting for at least six months.

The US Constitution is widely regarded as the longest-standing written national constitution still in force—see how it has influenced rights worldwide.

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.

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

Massive 3D printers have been used to build homes by stacking layers of 'concrete toothpaste,' a fire-resistant material that effectively insulates against outside noise.

A researcher recently discovered an interview from 1967 between groundbreaking journalist Joan Didion and the Grateful Dead, years before the band became an institution.