Lactose intolerance is not the same as a dairy allergy

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

Lactose intolerance is a digestive condition that occurs when the small intestine has difficulty breaking down lactose, a sugar found in products like milk or cheese, leading to symptoms such as diarrhea or bloating. Almost 70% of the world’s population may have lactose processing issues, particularly in Asia and Africa. This is different from a condition called cow's milk protein allergy—an immune system disorder that can cause hives and anaphylaxis.

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.

Adults are developing food allergies that they didn’t have as children

Research published in 2019 found that almost half of 40,000 surveyed adults with food allergies developed a new food allergy as adults, underscoring that our immune systems may newly misclassify substances later in life.

Even in recent history, adaptations to the environment drove human evolution

Through genetics, environmental pressures, and cultural influences, humans have evolved to tolerate lactose, develop varying skin pigmentation, and acquire genetic resistance to diseases like bubonic plague. The metabolic and digestive systems of Indigenous peoples have adapted to their diet, which is influenced by the availability of food and water.

Type 1.5 diabetes is typically found in adulthood

Clinically referred to as latent autoimmune diabetes in adults, or LADA, this condition is often diagnosed as Type 2 diabetes. However, it’s an autoimmune disease that eventually requires insulin, just like Type 1 diabetes. Misdiagnosis can result in uncontrolled high blood sugar and a slew of other serious health issues.

Twin studies suggest celiac disease is among the more genetically-linked disorders

Genetics appear to play a larger part in this condition's development than many other autoimmune disorders. Research shows a roughly 60-75% genetic probability that if one identical twin has it, the other will too. Celiac triggers a small intestine attack when people eat gluten, a protein commonly found in wheat, barley, and rye.

Lengthy incubation periods are why it’s tough to link foodborne illness to specific foods

People may not get sick from a foodborne pathogen for several days after consuming it, making it a challenge to link the illness and its cause. Factors influencing when a person starts feeling sick—even as the pathogen is multiplying in the gut—include individual variations in immune systems and gut microbiomes, what other foods are in the person’s body, and how much of the pathogen was consumed.

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.

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.

Tick bites can fuel an allergy to a sugar molecule in red meat

Alpha-gal syndrome is on the rise globally as ticks spread due to climate shifts. Bites from some ticks can trigger a sensitivity to a sugar molecule called alpha-gal found in mammal meat, which can lead to allergic responses to hamburgers and steak, among other products. Listen to an expert’s tips for avoiding this allergy, including quickly removing any ticks to limit exposure to their saliva or vomit.

Post-treatment Lyme disease syndrome may be caused by bacterial remnants in the liver

PTLDS, which refers to lingering symptoms of Lyme after antibiotic treatment, is an area of active research. Rodent research published in 2025 suggests that these ongoing symptoms may potentially be due to the body's inflammatory response to lingering cellular components from the bacteria that cause Lyme, Borrelia burgdorferi. In rodents, components of the bacteria's cellular wall may remain in the liver after the bacteria were eliminated with antibiotics.

About 95% of people are naturally immune to leprosy

Contracting it requires prolonged contact with someone with the disease, meaning you'd have to be living with them. You cannot get leprosy from hugging someone with leprosy or sitting next to them. It's not known to pass from mother to fetus. The risk of transmission from armadillos is also likely low, but people should avoid touching wild animals for general safety.

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.

MS risk is shaped by geography, not just genes

Latitude—and related vitamin D exposure—seems to affect MS risk. People who migrate from a high-risk MS latitude (like northern Europe or the northern US) to a lower-risk latitude (like tropical areas) before age 15 tend to adopt the lower risk of their new country—suggesting there's a critical window for environmental exposure.

Genetics play a role in the reliability of the body's biological clocks

Growing evidence suggests genetics influence when, how long, and how well one sleeps, meaning insomnia may have a genetic component. While exact insomnia biomarkers have yet to be determined, some genes, including those related to psychiatric disorders, have been implicated.

Women typically have more robust immune responses than men

This difference helps women better combat infectious diseases, but this more turbo-charged response may also make women more vulnerable to autoimmune diseases by potentially priming their immune systems to overreact to their own cells and tissues and label them as invaders that must be destroyed. Roughly 80% of American women have autoimmune conditions.

Your DNA may determine whether you like coffee or tea

Whether people prefer coffee or tea may boil down to a matter of taste genetics. People with a version of a gene that increases sensitivity to the bitter flavor of caffeine tend to be coffee drinkers, according to a report. Read on for more.

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.

Understanding insulin

Scientists Daniel and Kelly talk with researcher Dr. Katrine Whiteson about diabetes, the history of insulin production, and Dr. Lydia Villa-Komaroff—an essential member of the team who discovered that bacteria could be induced to produce insulin. Listen to discover interesting facts about the life-saving medicine and how it works in the human body.

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.

Pregnancy at older ages increases the chances of fetal abnormalities

Chromosomal irregularities are more likely at older maternal ages so genetic testing for a fetus of mothers-to-be at age 35 and older is often recommended. Conditions that can be screened for in utero include cystic fibrosis, Tay-Sachs disease, sickle cell disease, Down syndrome, spina bifida, Duchenne muscular dystrophy, and more.

Eating competitions can ruin a stomach's elasticity

Competitive eaters make room for all that food by toying with the stomach's ability to expand and contract. Still, doctors warn that repeated stress can destroy that ability, leading to further issues.

The ubiquitous 1990s “Got Milk?” ad campaign was intended to fix milk’s dwindling popularity in the late 20th century

Despite its success in spreading the word about milk, the sales numbers weren’t quite as impressive. This Mental Floss article details the marketing efforts themselves, as well as how milk lobbyists didn’t necessarily succeed despite their revolutionary ads.

Budweiser still uses the same yeast lineage derived from the one used in the 1800s

During the late 1800s when Budweiser beers hit the market, darker, all‑malt lagers dominated the US beer market. Budweiser was brewed with a single, consistent yeast strain that gave it a crisp uniform flavor, differentiating it from darker beers.

It seems like we shouldn’t have to say this: Cheese is not like crack

While news reports may claim cheese is addictive, the facts behind the research show cheese and crack have little in common. It appears that highly processed foods with high levels of sugars and fat, rather than cheese specifically, are most closely associated with addictive-like behaviors. In fact, cheese ranked lower than foods like pizza, chocolate, and fries in terms of its addictiveness.

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.

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

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

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.

Indefinite cloning of some endangered species may not sustain their longevity because cloning success rates decrease as genetic mutations accumulate.

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.

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

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

Listen to an in-depth conversation on the links between Parkinson's disease and herbicide exposure and the challenging pace of scientific investigation.

In 1939, baseball star Lou Gehrig delivered his inspirational 'Luckiest Man' speech after retiring due to the health condition that now bears his name.

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

See the evolution of Ebola vaccine and treatment development.

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.

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.

For centuries, it was common to sleep in two shifts: a few hours at the beginning of the night, and a longer period beginning around midnight

The Great Salt Lake's distinct dual coloration results from high-salinity organisms that only live in the northern portion and produce a purple protein.

Volcanic activity may have triggered the Black Death by spewing gases that led to crop failures in Europe, thus forcing the import of grain ships with plague-infested fleas.

20,000 letters to the advice columnist 'Dear Abby' provide insight into prevailing sex, religion, and LGBTQ fears, anxieties, and concerns from the 1950s onward.

Salvador Dalí believed he was his own dead brother, who had died nine months before he was born

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.

Use this tool to calculate the dollar value of your parental mental load, from meal planning to coordinating after-school care, then see resources that help generate solutions.

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

Children are now three times more likely to say they want to be a YouTuber when they grow up than an astronaut, with some even attending 'YouTube camps' that teach kids how to create content for the platform.

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

In preparation for this weekend's Eurovision finale, which is something like the World Cup of pop music, here's a young Céline Dion performing (for Switzerland?) at the 1988 competition.