Embracing poor hygiene in early life won't stave off allergies

Modern conveniences may be contributing to allergy increases

A combination of genetics and how the environment changes our genes are likely contributing to the rise in allergies. But daily conveniences, such as dishwashers and packaged baby food, also change the level of bacterial exposures in early life, with potential implications for allergy development, experts from Mount Sinai Health System state in this video discussion.

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.

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.

Home allergy tests don’t work well and experts urge caution

Doctors do not recommend at-home allergy test kits because their results may be inaccurate and confusing, and lead people to make lifestyle changes that are not warranted. Tests that require sending in a hair sample, for example, will not be helpful because hair does not have the relevant antibodies that blood testing would detect.

Seasonal allergies don't always show up in childhood

The human immune system may become sensitized to pollen and develop an allergic reaction to it after prolonged exposure. Other triggers for new seasonal allergies may include exposure to new environments and changing climate conditions that affect allergy season length and conditions for various pollens.

Amish kids have far fewer allergies than the general population

Only about 7% of Amish children in a northern Indiana community have tested positive for common allergens in routine skin prick tests, whereas half of the general US population tests positive for them. Asthma is also extremely uncommon among the Amish, even when compared with other farming communities. Researchers are interested in exploring if approaches like exposing kids across the general population to Amish farm dust might stave off some allergies.

Research suggests the cleanliness of the ISS may make astronauts unhealthy

The International Space Station's sterile conditions deprive astronauts of the opportunity to strengthen their immune systems through microbial exposure. To address this problem, future missions may use probiotic-based cleaners and foster diverse microbes in space habitats.

Improved 19th-century sanitation meant kids encountered polio later, with worse results

Almost all children likely used to contract poliovirus, but scientists suggest that when infants encountered it very early in life—due to poorer conditions and hygiene—they still had some maternal protection from pregnancy or through breastmilk, so the symptoms were more flu-like.

Hookworm infection, though risky, may help fight certain health conditions

Early clinical trial research suggests that the parasites trigger the production of specific proteins that quiet our immune systems. This keeps the parasites from being killed, but it also quiets the inflammatory response that underpins allergies, type 2 diabetes, celiac disease, and other autoimmune conditions. Researchers still caution that infection with too many hookworms can cause serious medical complications and that this is not a standardized or approved medical treatment.

Peanut allergies dropped by 43% after doctors reversed avoidance guidance, but questions remain

The study’s data appear to confirm the policy shift. Still, since the study did not include an examination of infant diet, researchers can’t definitively say that the guideline shift led to dietary changes and thus directly caused the decline.

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

Food allergies were first documented more than 4,000 years ago

Although food allergies are on the rise in modern times, they have been documented in written records for thousands of years. More than 3,000 years ago, Chinese emperors advised patients to avoid certain foods, and Hippocrates noted in his work that food could cause serious harm to certain individuals, and even lead to death.

On average, people smell worse if they're sick

For a small 2014 research study, a panel was tasked with sniffing the smelly t-shirts of people who had been injected with a compound known to activate the immune system and those of controls without the shot. It found that those who were acting as if unwell (due to the injection) generally smelled worse. Subsequent work found that those who sniffed unpleasant odors had a mild immune response of their own—perhaps to protect them from disease. (Some users may experience a paywall.)

Most penicillin allergy diagnoses are wrong

A Freakonomics Radio episode investigates why so many people mistakenly believe they’re allergic to penicillin. This widespread misdiagnosis leads to costlier, less effective treatments and contributes to the growing problem of antibiotic resistance.

The history of germ theory, which explains that illnesses are caused by microorganisms

For centuries, the miasma theory, which held that illnesses were caused by clouds of "bad air" produced by decaying organic matter, was the accepted explanation for the spread of disease. The development of microscopes and the subsequent technology to isolate bacteria and test disease spread in mice greatly contributed to contagionists overturning miasmatists.

Broken or neglected air conditioners are risky for respiratory health

A well-maintained air conditioner can typically keep out unwanted pathogens, but units that are dusty or water-logged can foster germs and cause harm. AC units also remove moisture from the air, potentially causing mucus membranes to dry out and become vulnerable to infection.

'Mental hygiene' was the 1843 term for mental health

It was coined by American psychiatrist William Sweetzer to reference the same idea as personal hygiene. Mental hygiene, in Sweetzer's view, needed to be maintained in the same way people attend to their personal cleanliness, an idea that was supplanted by better understanding of the complexities of mental health disorder causes in the decades that followed.

Nasal hairs, called vibrissae, help protect the body from particulate matter and other dirt

The nose structure plays a key role in filtering air before it enters our lungs and makes sure that the air temperature and humidity are also suitable for the body.

Perceived isolation ages you

Mounting evidence suggests that socialization is a vital component of maintaining good health. Research published in 2024 from Mayo Clinic researchers analyzed the social lives of more than 280,000 adults and concluded that individuals that weren't likely to participate in extracurricular social activities and get-togethers were more likely to have a biological age older than their actual age—meaning that you may be 60 but health indicators would suggest you're older.

In recent years a child anxiety expert has created and tested a novel phobia and anxiety treatment approach for children, focused on changing how parents respond to the fears.

Ear infections can arise from chlorinated water, too

Any water remaining in the ear can lead to swimmer's ear. Chlorinated water, however, can also strip the skin of the oils and wax that would otherwise protect the ear.

Health problems are being misdiagnosed as perimenopause symptoms

Symptoms of menopause and perimenopause (the premenopause period) can be varied enough that clinicians dismiss them in patients in their mid-30s and onward as just a symptom of hormone level change. In this story, a woman's itching was dismissed as a hormonal change, but after two years and 11 separate doctor consultations, was diagnosed as cancer. (Some users may experience a paywall.)

Cats evolved from arid land animals, contributing to their aversion to water

Although positive water experiences can make some cats water-loving, they usually self-clean, making baths unnecessary.

Poison ivy can cause rashes year-round since all parts of the plant contain urushiol, the oil that triggers our allergic response.

The American Veterinary Medical Association advocates for vaccinations for pets to extend their lives

The American Animal Hospital Association provides guidelines, while many states legally require certain vaccines, such as rabies. Vaccinating healthy pets—even indoor-only pets—prevents outbreaks and protects other vulnerable animals, and adverse effects, such as allergic reactions and injection-site irritation, are rare. (Some readers may experience a paywall.)

Urushiol, the oily toxin in poison ivy, can remain allergenic on clothing for years

The substance can still cause rashes even after being on shoelaces, clothing, sleeping bags, boots, or other clothing for multiple years—some reports say five years on surfaces—so they all need to be washed after outdoor adventures with the plants.

An intense fear must persist for at least six months to be diagnosed as a phobia

Research suggests that both environmental and genetic factors can contribute to the onset of these intense, irrational fears. Often, they can stem from an early traumatic experience, but not always.

What the research says about the link between lead pollution and crime

The lead-crime hypothesis links childhood lead exposure to impulsivity and aggression as an adult, traits typically associated with higher crime risk. A 2022 meta-analysis found that reducing lead may explain up to 28% of the US homicide decline, but not the broader crime drop.

Fear or disgust related to clusters of holes and cracks, called trypophobia, may stem from evolutionary processes to help us avoid pathogens.

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

An investigation suggests a Scottish island became awash in forever chemicals via seafoam and seaspray—raising questions about what that means for the safety of other coastal areas.

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.

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

Chaos theory—informally known as the butterfly effect—is the reason why weather forecasts are presented with probabilities rather than certainties.

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

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.

Human-to-human transmission of hantavirus remains extremely rare, so the 2026 hantavirus cruise ship outbreak doesn't mean we're facing a COVID-style pandemic risk.

Watch the cumbersome, but necessary, precautions healthcare workers must take to care for and protect themselves while caring for Ebola patients.

To reduce wrinkles in clothing, research recommends gentle wash cycles with more water and tumble drying with smaller loads and longer times.

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

The hormonal disorder PCOS was renamed PMOS in 2026, a move designed to improve care and research by shifting the focus to the hormonal causes of this condition that affects 1 in 8 women.

SpongeBob exemplifies Aristotle's philosophy for living well because he understands that happiness doesn't come from external factors like money, recognition, or power.

US housing costs have risen by roughly 175% between 1991 and 2026—but a growing number of Gen Zers are becoming homeowners anyway. In 2025, 4% of homebuyers were Gen Z, up from 3% the year before.

When a Paris department store hesitated to sell Estée Lauder's perfume, she 'accidentally' broke a bottle, causing the smell to spread throughout the store and shoppers to start asking to buy the scent.

Recent research found that the brain doesn't seem to massively rewire following amputation—upending earlier beliefs about the cause of phantom limb pain.

Brian Wilson wrote the Beach Boys' 'Don't Worry Baby' for the Ronettes, but the legendary girl group rejected it.

Clever Hans was a 1900s horse that was believed to be able to solve math equations, tell time, and read and comprehend German, until a psychology student discovered how he got his answers.

Pure water does not conduct electricity because this flow of energy requires the movement of charged particles, and water is a neutral molecule.

Many legends about George Washington, including his supposed wooden teeth and the story of cutting down the cherry tree, lack evidence.

The tragic Pulitzer Prize-winning image 'The Vulture and the Little Girl' (1993) generated controversy, raised concerns about ethics in photography, and eventually led to the photographer's death.