Most of the world’s population has difficulty processing lactose—but that’s not an allergy

Lactose intolerance is not the same as a dairy allergy

Lactose intolerance can develop in adulthood and can be influenced by genetic factors, culture, and dietary practices. Times of famine may have favored those who could digest dairy, naturally selecting them more, resulting in lactase persistence.

About two-thirds of humans lose their ability to produce lactase after weaning

Lactase is an enzyme that digests lactose—a sugar in milk and dairy products. While genetics strongly determines lactase persistence, factors like famine, disease exposure, and gut bacteria also influence symptoms and evolution.

Why there’s barely any cheese in traditional East Asian food

East Asian cuisine has historically been cheese-free, but why? Several unique circumstances combined to limit—or eliminate—the dairy product in dishes from Japan, Korea, China, and other nearby countries: Livestock were seen as working animals rather than nutritional sources, and most people were lactose intolerant. As Western cuisine becomes more popular globally, though, cheese is making its way into more East Asian diets.

Kids often grow out of allergies to milk and eggs

Between 60% and 80% of kids with allergies to milk or eggs outgrow them by age 16. The immune system doesn’t always recognize and respond to baked forms of these allergens, so when kids eat muffins and other cooked food products, their immune system may become more habituated to them and overcome food sensitivities. Aging out of other allergies is less common.

More than 90% of America’s food allergies are triggered by 9 foods

Milk, egg, peanut, tree nuts, soy, wheat, fish, shellfish and most recently, sesame, are recognized as the most common food allergies in the US. Together, they are responsible for at least 90% of the serious food allergy responses in the country.

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.

Why some people have allergies

Why do some people have allergies while others don’t? One theory suggests allergies are a relic of our evolutionary past. Our immune system, once primed to fight parasites, now mistakes harmless substances for threats.

Alpha-gal allergy is a problem for red meat lovers, and that same sugar is an issue for xenotransplants, too

In recent years, researchers have discovered ticks can induce spontaneous meat allergies in people they bite, a particularly problematic condition for previous meat lovers. This 18-minute podcast from RadioLab breaks down the cause.

Animals' stomach lining produces cheese

Cheesemaking would be impossible without rennet, the enzyme that separates milk’s liquid and solid components. Rennet occurs naturally in the stomach lining of young goats, cows, and lambs to help them digest milk, a process that also allows cheesemakers to use it to make curds. Now we have plant-based rennet that comes from thistles, artichokes, and other similar plants.

Artificial sweeteners may disrupt gut health

Some research suggests that certain sweeteners can throw off the balance of beneficial bacteria in the gut and shift the composition of the microbiome. Such changes, depending on an individual's specific gut flora and levels of sweetener consumption, could potentially affect metabolism and glucose tolerance or lead to bloating and diarrhea.

More than 1 in 7 people worldwide have had Lyme disease

Research published in 2022 suggests that 14.5% of the world's population has contracted Lyme disease. Researchers arrived at that estimate by analyzing the presence of Lyme disease antibodies (indicating prior infection) across 89 studies conducted between January 1984 and December 2021. The works collectively included blood samples from more than 150,000 people. (Some user may encounter a paywall.)

Diabetes 101: Insulin deficiency leads to high glucose levels in the blood

Glucose, the brain's preferred energy source, enters the bloodstream when the body breaks down consumed carbohydrates. To manage this increase in readily available energy, the body releases the hormone insulin, which allows glucose to enter and fuel our cells. Without insulin, glucose remains in the blood, causing health issues.

Inflammaging appears to differ across global populations

Chronic, low-grade inflammation linked to aging is a byproduct of our industrialized lifestyles, according to recent research. The work compared two industrialized populations with two Indigenous, non-industrialized populations in Bolivia and Malaysia, and found that inflammation levels in the Indigenous groups—unlike the industrialized ones—did not seem to differ by age.

Climate shifts are projected to cause more cases of food poisoning

Research published in 2024 suggests that with more severe heatwaves and natural disasters, scientists expect there to be a rise in foodborne disease, especially in Africa and Asia. Already, there are an estimated 600 million food poisoning cases and 420,000 deaths annually. Diarrhea is the most common cause of those deaths.

More than 5% of the world's population has disabling hearing loss

Disabling hearing loss is defined as hearing loss greater than 35 decibels in the better hearing ear. (For context, that means the sound of leaves rustling, at roughly 30 decibels, would be inaudible even to your better-hearing ear.) The World Health Organization's data suggests that more than 5% of the world's population has this level of loss requiring rehabilitation, which amounts to 430 million people—including 34 million children.

Most Westerners don't need more protein, despite the protein boom

You can find the macronutrient in snack bars and pretzels, shakes, and more, even though most normal diets in the West are already protein-heavy with meat and milk. A mix of increased exercise culture and influencer sway has led to a market hungry for it.

Learn how cholera bacteria sicken humans

Once a person has ingested large amounts of the bacteria, typically through contaminated water, cholera bacteria begin producing and releasing a toxin inside their host. It attacks the mucosal lining of the intestine, making it hard to absorb liquids. This process leads to cholera's characteristic symptoms, like voluminous, watery diarrhea.

Less than 0.1% of the approximately 20,000 known bee species make honey

The majority of honeybee species originate in South and Southeast Asia, with the largest—Apis laboriosa—found almost exclusively in the Himalayas. The smallest is the black dwarf honeybee, Apis andreniformis, which inhabits tropical and subtropical regions of the continent.

Plant based milk is good for the planet, but not quite as good for you

Rising in popularity, plant-based milks are a practical alternative for consumers concerned about sustainability and climate change. Plant-based milks, such as oat, almond, rice, and soy milk, generate about one-third of the greenhouse gases and use...

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

See examples of leprosy in the Bible—a broad term for skin ailments in ancient times

People afflicted with leprosy in the Bible may have had a range of different skin diseases, rather than what's clinically diagnosed as Hansen's disease (leprosy) today. In the Bible, as in many traditional societies, those with the disease were often considered unclean or sinful.

GLP-1s are netting interest for treating autoimmune diseases, but are considered experimental

Already used to treat type 2 diabetes, the novel medications are showing some early promise in experimental studies at reducing inflammation and treating autoimmune conditions including rheumatoid arthritis and inflammatory bowel conditions. But researchers caution that side effects are still under investigation—rarely the medication has caused lupus, an autoimmune disease.

View a map of countries with the safest and most dangerous drinking water

More than a quarter of the world's population lives in water-stressed countries, and a similar number use contaminated drinking water sources, which can lead to widespread disease, according to the World Health Organization. The Environmental Performance Index shows which countries have safe drinking water.

What causes high cholesterol?

Cholesterol is a complex health issue, and for a long time, the American Health Association recommended Americans not eat more than three eggs a week to avoid it. But scientific advancements on the impact of different types of cholesterol revealed eggs aren't so bad. So what is it, and how does it effect us? Dive into the digestive tract here.

How humans digest food

Every day, the average human eats close to six pounds of food—all of which must be processed by the digestive system. Ten organs collaborate to transform food that the mouth chews into the energy needed to stay alive. (Stretched out, these organs...

Many religions have core majorities in certain countries

Though most religions have members across the world, they also have major concentrated populations in specific nations. For example, 95% of Hindus live in India, while 85% of the world's Jews live in Israel and the US.

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.

Lesser-known phobias include turophobia, or the fear of cheese, and nomophobia, the fear of being without your cell phone.

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

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.

Telehealth demand for GLP-1s for weight loss is booming as consumers seek easier access.

The 2026 Ebola outbreak is hampered by a lack of vaccine against the species of the virus, heightening the need for rapid tests to aid in disease control.

Most of the observable universe's volume consists of voids and supervoids—enormous regions of space with little to no galaxies, stars, or light.

The first line of 'immortal' human cells, which can divide indefinitely and are used in scientific research, was nonconsensually taken from a Black woman.

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.

Budweiser stores yeast derived from the original 1800s strain in a secret bunker, which only the Head of Yeast Management can access—not even the CEO

Louisiana's 'Cancer Alley' is infamous for having some of the highest industrial pollution, toxic air emissions, and cancer risks in the US.

While El Niño moves warm Pacific Ocean waters east along the equator, La Niña moves them west, shifting where rainfall will become more common for months.

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.

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.

Radioactive elements can introduce software errors because the ionizing radiation they produce can detach electrons from atoms, and computer code relies on the distribution of electrons.

US consumers collectively owe more than $1T to credit card companies—almost as much as they owe in auto loans.

The US first hosted the World Cup in 1994, a tournament that lives in soccer infamy for its poor planning and the murder of Colombian player Andres Escobar, who'd accidentally scored on his own net.

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

The United States is one of only around two dozen countries with a fully federal system of government, in which power is divided between national and state governments.

A 2019 Facebook event called on attendees to "Storm Area 51, They Can't Stop All of Us," resulting in countless memes, the creation of a music festival, and eventually the arrests of those who did try to approach the area.

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.

Take a 3D tour of the Hajj, Islam's annual pilgrimage to Mecca, undertaken by over 1.5 million Muslims.

Researchers believe the brain consolidates memories, processes emotions, and plans for the future during dream states