In 1989, an epidemiologist in Britain, David Strachan, observed that babies born into households with lots of siblings were less likely than other babies to develop allergies and asthma. The same proved true of babies who spent significant time in day care. Dr. Strachan hypothesized that the protection came from experiencing an abundance of childhood illnesses.Interesting. I wonder if using those anti-bacterial wipes in the kitchen make kids more likely to get asthma or allergies.
Dr. Strachan’s original hygiene hypothesis got a lot of press, not only in the news media but in serious medical journals. Less publicized was the decade-long string of follow-up studies that disproved a link between illnesses and protection from inflammatory disorders like allergies and asthma. If anything, studies showed, early illness made matters worse.
Moreover, studies now show that the more infections a person has during childhood, the greater his or her chance of premature death from scourges of old age like heart disease and cancer. The link appears to be chronic inflammation, a kind of lingering collateral damage from the body’s disease-fighting response.
Still, Dr. Strachan’s original observation was confirmed — as a group, babies in large families and day care are less likely to develop allergies and asthma than are children born into smaller families and kept at home. The same protective effect can be seen in children born on farms and in areas without public sanitation.
But the link isn’t disease-causing germs. It’s early and ample exposure to harmless bacteria — especially the kinds encountered living close to the land and around livestock and other young children. In other words, dirt, dung and diapers. Just as disease-causing microbes clearly bring on inflammation, harmless microorganisms appear to exert a calming effect on the immune system.
I also wonder if there is a way to bring the harmless bacteria into an urban environment for exposure to kids living in pristine environments. As someone who went through endless rounds of allergy shots as a kid, that sounds like a vast improvement to me. Would be a great business to market to new parents if it were possible.
via NY Times