The Hygiene Hypothesis

The hygiene hypothesis is holds that a lack of exposure to germs, allergens, and parasites increases susceptibility to allergic diseases and weakens the human immune system. We live in a very clean and sterile environment here in the Western World - our foods are washed, cooked in clean pots with clean water and by clean hands. We bathe a lot, we have antibiotics, anti-fungals, and anti-viral medicines available. Even in our regular medicine cabinets - Bactine, hand sanitizers, anti-bacterial soaps, anti-viral Kleenex, bleach, HEPA filters on our vaccum cleaners, heavy-duty laundry detergent, and band-aids with the antibiotic built right in. Don't get me wrong, this is all GOOD to have. The downside is, we tend to overdo it. Our environment is SO clean, that our immune system isn't getting the regular "boosts" that it needs to regulate itself. My old pediatrician was from India and was surprised to see so many allergies here as well. Apparently, they're pretty rare over there. Kids are exposed to more germs and allergens on a daily basis, so they develop pretty well-tuned immune systems for the "minor" things. Our babies are kept so clean and sanitized that we may be delaying their normal immune development.

From LiveScience.com via Yahoo:

"Exposing kids to nasty germs might actually toughen them up to diseases as grown-ups, mounting research suggests.

A new study suggests that higher levels of exposure to common everyday bacteria and microbes may play a helpful role in the development of the body's inflammatory systems, which plays a crucial role in the immune system's fight against infection.

"Contrary to assumptions related to earlier studies, our research suggests that ultra-clean, ultra-hygienic environments early in life may contribute to higher levels of inflammation as an adult, which in turn increases risks for a wide range of diseases," said McDade. "In the U.S we have this idea that we need to protect infants and children from microbes and pathogens at all possible costs. But we may be depriving developing immune networks of important environmental input needed to guide their function throughout childhood and into adulthood."

The study will be published online on Dec. 9 in the journal Proceedings of the Royal Society B: Biological Sciences. "

According to the American Academy of Allergy Asthma and Immunology, the number of people with asthma increased by 75 percent from 1980 to 1994. According to the Hygiene Hypothesis, asthma cases are increasing due to children being exposed to fewer allergens earlier in life.

The Hygiene Hypothesis was first put forth by David P. Strachan in 1989 with an article he published in the British Medical Journal. His research showed that hay fever, eczema, and other allergies were far less common in children with many siblings. He postulated that this was due to the children being naturally exposed to many more pathogens and allergens by living in close quarters with a larger number of people. This work has been extensively researched by epidemiologists and allergists since its publication and found to be sound. This theory has been used to show why allergies and immune disorders have been on the rise since the Industrial Revolution and have a much higher occurance in developed countries. As the knowledge base of this research has grown, the hypothesis has also been applied to agents other than allergens as well. It also explains why certain groups of people have stronger immunities against "minor" illnesses such as colds and flu.

By Amy Norton
Sat Aug 2, 3:30 PM ET

NEW YORK (Reuters Health) - Children who grow up in a spic-and-span home may have a higher risk of developing inflammatory bowel disease, a study suggests.

Inflammatory bowel disease, or IBD, refers to a group of conditions marked by chronic inflammation in the intestines, leading to symptoms like abdominal pain and diarrhea. It's thought that the conditions arise from an immune system overreaction that injures the body's own intestinal tissue.

In the new study, published in the American Journal of Gastroenterology, researchers looked at whether the so-called "hygiene hypothesis" might be involved in young people's risk of developing IBD.

The hygiene hypothesis was first advanced in the late 1980s as one explanation for the rise in allergic diseases in developed nations.

The theory is that when children are exposed to few viruses, bacteria and other microorganisms early in life, their immune system development is affected in a way that raises the risk of abnormal immune reactions.

For example, studies have found that young children who spend time in daycare, where they are likely to be exposed to viruses and other microorganisms, are less likely to develop allergies than their peers who spend little time around other children early in life.

For the current study, Dr. Eran Israeli and colleagues looked at the relationship between IBD risk and certain markers of how "hygienic" a child's upbringing was -- including how many siblings a child had, his or her spot in the family birth order, and whether the family lived in an urban or rural area. A rural environment is considered generally less hygienic than an urban one.

The researchers found that among the nearly 400,000 Israeli teenagers included in the study, 768 -- or 0.2 percent -- had been diagnosed with IBD. Those with one sibling were between two and three times more likely to have IBD than teens with five or more siblings.

Similarly, teenagers who lived in an urban setting were 38 percent more likely to suffer from IBD than their rural counterparts.

The findings do not prove that the hygiene hypothesis is at work in IBD, according to Israeli, of Hadassah Medical Center-Hebrew University in Jerusalem.

The study, he told Reuters Health, looked only at "surrogate markers" of childhood hygiene and showed an association between those markers and IBD.

But if the extra-clean surroundings of modern life do indeed contribute to IBD development in certain susceptible individuals, what are the implications?

"It would of course be impractical to suggest living in a less 'hygienic' environment or changing living conditions in order to afford possible protection (from) future development of IBD," Israeli said.

However, he added, it might be possible to lower IBD risk in people who are at higher-than-normal risk -- such as those with family members with the disease -- by exposing them to harmless microbes to help regulate their immune responses.

Researchers have already begun studying whether exposure to harmless parasitic worms might help treat Crohn's or colitis. Studies have not yet investigated such tactics for preventing IBD in healthy, high-risk people, Israeli noted.

SOURCE: American Journal of Gastroenterology, July 2008.

From Yahoo News August 2, 2008

When we are born, we carry immunities bestowed upon us by our mothers. Antibodies from our mothers are passed to us through the placenta. For babies who are breastfed, this immunity increases and lasts longer. Our immune system matures and "learns" how to function by what we are exposed to. Think about the common cold. The virus which causes a head cold can only get your sick once, after that you are immune to it because your immune system has learned how to prevent that particular invader from wrecking havoc. The key term, however, is "particular". Because these viruses mutate so quickly, the next time you catch a cold, your immune system won't recognize the invader. The more of these viruses we are exposed to, the more anibodies we have in our arsenal.

Sometimes, however, our immune system gets confused. Messages are sent to attack and form antibodies against agents which are not harmful to us by nature. This is where allergies come from. Much of this process is not understood yet by science - why one person develops an allergy to eggs, someone else to wheat, and yet another person has hay fever and asthma. The Hygiene Hypothesis explains why allergies may develop - the more sanitized an person's environment is, the fewer antibodies the immune system will develope. In the long term, this weakens the immune system and also may cause inappropriate immune responses like attacking harmless substances such as latex, pet dander, pollen, and certain food proteins.

It has been theorized that children who are regularly exposed to cattle develop fewer allergies all-around. Apparently, this resistance comes from regular and early exposure to cow dander - hmmmm, I wonder if you can get cow dander on Ebay?

In 1918 a particularly deadly form of Influenza A appeared. By the time the epidemic came to an end in 1920, millions of people worldwide had been killed by it. Estimates of Flu-related deaths range from 20-100 million.

The particular strain of flu - Influenza A H1N1 type, spared many older adults while younger, healthier, people were killed. This strain was similar enough to a previous strain, that many elderly people carried at least partial immunity already to it.

Historical and laboratory research on the 1918 epidemic has led to concerns over how the next "big" pandemic will affect us. With so many individuals receiving vaccinations against the seasonal influenza viruses each fall, our immune system may not be prepared to fight off a newer, deadlier strain and labs may not be able to develop a life-saving vaccine in time should a highly virulent strain arise suddenly.

National Jewish Hospital in Denver, Colorado (the top asthma hospital in the nation) has extensively studied the hygiene hypothesis.

Read the complete article here

AN excerpt:

"February 25, 2003

Bacterial Infections Alter Allergic Response
Findings Support Hygiene Hypothesis

Researchers at National Jewish Medical and Research Center have gathered strong experimental support for the hygiene hypothesis, a proposed explanation for the worldwide rise in asthma and allergies. The research team, led by Richard Martin, MD, found that early infection with the bacterium Mycoplasma pneumoniae reduced a mouse's subsequent response to allergens. Alternatively, mice exposed to allergens prior to infection, developed a stronger allergic response. The research team is reporting its results in the March 2003 issue of the journal Infection and Immunity.

"For the first time, we have shown that a bacterial infection can modify the allergic response," said Dr. Martin, Vice Chair of the Department of Medicine at National Jewish. "Timing is everything, however. Our results suggest that M. pneumoniae, or a related pathogen, could help prevent asthma and other allergic diseases, but only if the infection occurs before a person is sensitized to an allergen."

Asthma and allergies have both been on the rise for several decades, especially in developed countries. The hygiene hypothesis has offered one explanation for this increase: compared with the past, children living in these countries today are exposed to fewer infectious organisms, which are necessary to properly train their developing immune systems. As a result, their immune systems overreact to relatively harmless irritants, leading to allergies and asthma."

The million dollar question - What does it mean?

Unfortunately, there are no answers. Do we want to go back to living in squallor? No. Sure, children born in impoverished nations might be spared a myriad of allergies and immune disorders, but they still die of horrific diseases which are almost unheard of here. Diseases like Tetanus, Polio, Measles, infectious diarrhea. Our modern, clean, world affords us luxuries that few others on the planet can imagine.

Are we TOO clean? Probably.

What can we do about it? I'm not sure if there are any good answers, but I have come to a few conclusions:

It's OK to let them play with critters.

The 5 second rule can probably be upped to 15 or 20 seconds without any dire consequences.

Every little sniffle or sneeze does not need to be drugged out of them.

And, most importantly, it's OK to let them play in the mud. Sometimes.

I am a mother of 4 children, one of whom has severe food allergies to wheat, corn, rice, watermelon, soy, pork, oats, legumes, and tree nuts. I am a Classically trained Homeopath (CHom) and Holistic Health consultant in private practice.

So, if *most* germs are GOOD, then why are we buying so many antibacterial soaps, hand sanitizers, and household "disinfectant" sprays??

Simple Answer:

Money. Moolah. Cold Hard Profit Margins.

The companies who manufacture these types of items know a good thing when they see it. The sales of these products rake in MILLIONS of dollars each year. Brilliant marketing has made our whole society scared to death that their may be a single germ anywhere on our bodies, our counters, or our bathroom sinks.

Do you remember a few years ago when one of the prime-time news shows did the big report on how there was e.Coli all over our kitchens and how no one was really "clean" enough? Scary stuff, for sure. But I wonder, if all of those kitchens were such cesspools of mortal danger, why weren't the poor people dead already? The news crews brought in the black lights and found bacteria EVERYWHERE - there was even *gasp* bacteria on the inside of the refrigerator door handles! So, how on earth did those poor folks manage to stay out of the hospital? Why weren't we dying left and right from kitchen and bath germs then?

We weren't.

And we wouldn't be now either.