Hygiene Hypothesis: Is being Too Clean Causing Food Allergies?

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Today’s household, living in the Western World, is vastly different from even 100 years ago. Hand sanitizer, vaccinations, antibiotics and Lysol® are the norm, keeping our homes and children more germ-free than ever. But are our cleaner households causing the rise in food allergies and autoimmune disorders?

What Is the Hygiene Hypothesis?

The hygiene hypothesis suggests that the lack of exposure to parasites and microorganisms interferes with normal immune system function, which can then lead to the development of food allergies, asthma and autoimmune disorders. In sanitary environments, the immune system is under-stimulated, but this system isn’t designed to just sit back on the sidelines doing nothing. The result? The immune system focuses less on actually fighting off infections, and more on fighting things that it shouldn’t, such as nuts, eggs and other foods.

Dr. Erika Von Mautius formulated this hypothesis in the 1990s. When studying allergy rates in East and West Germany, Von Mautius expected to see more children with allergies in the less affluent East Germany cities; however, she found the opposite: children in the more sanitized and affluent West had a greater risk of having asthma and allergies.

Her original hypothesis disproven, von Mautius concluded that the lifestyle between East and West Germany, including the number of siblings in a family, the use of daycare, and the proximity of animals, has an impact on the immune system’s development. The immune systems of children exposed to more microbes are therefore more resilient and less likely to develop allergies.

Since von Mautius published her findings, several other studies appear to support her hygiene hypothesis.

Food Allergy Rates on the Rise

According to the American Academy of Allergy, Asthma and Immunology, food allergy rates have risen dramatically in industrialized countries during the past decade:

–          Approximately 8 percent of children have at least one food allergy
–          More than 38 percent of kids with food allergies have had a severe reaction
–          Peanut allergies alone tripled from 1997-2008
–          Allergies have been on the rise in the U.S. for the past 50 years

The Over-Sanitized Lifestyle

American children today certainly live a more sanitized lifestyle than their parents and grandparents. Family sizes are smaller, and most children live in suburb or urban environments, far away from farms and livestock and all their microbes. Modern children also spend more time indoors, use hand sanitizer, are vaccinated against diseases and have taken antibiotics at least once. This might mean they are safer from life-threatening diseases, but it could leave them vulnerable to developing life-threatening food allergies instead.

The Old Friends Hypothesis

The hygiene hypothesis is widely known, but it is not the only hypothesis that seeks to explain the cause of food allergies. One related hypothesis, the old friends hypothesis, suggests that the lack of friendly bacteria in Western children puts them at greater risk of developing allergies and other immune disorders. Supporters of this hypothesis point out that the microorganisms in the digestive tract of kids in western nations are vastly different from the healthy gut flora of children in impoverished and rural nations, who are at a much lower risk of developing allergies. And since more than 70 percent of the body’s immune system functions within the gut, perhaps the heavy use of antibiotics in western countries, which destroys beneficial gut bacteria, throws the entire system out of balance. More studies are needed to see if this is the case.

While the hygiene hypothesis is becoming more widely accepted, a lot of it is still speculation, and scientists need to perform more studies to determine what parts of our sanitized lifestyles actually cause food allergies. Are antibiotics to blame, or are our immune systems just unable to function properly without the presence of parasites? The cause is likely a combination of factors, but it will take more controlled tests for us to know for sure. In the meantime, while we might be tempted to avoid giving antibiotics and vaccines to our children, experts warn against it. Instead, they urge a more balanced approach that includes simple changes, like letting our kids play outside in the dirt more often.

References http://www.sciencedaily.com/releases/2007/09/070905174501.htm http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2841828/ http://www.pbs.org/wgbh/evolution/library/10/4/l_104_07.html http://fooddrugallergy.ucla.edu/body.cfm?id=40 http://www.aaaai.org/about-the-aaaai/newsroom/allergy-statistics.aspx https://www.microbemagazine.org/index.php?option=com_content&view=article&id=4700:a-darwinian-view-of-the-hygiene-or-old-friends-hypothesis&catid=950&Itemid=1301
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