Tuesday, December 8, 2009

Too Clean

Matt and Seth have been posting interesting things recently on the so-called hygiene hypothesis

Here is another study

Think again about keeping little ones so squeaky clean

"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 Thomas McDade, lead author of the study, associate professor of anthropology in Northwestern's Weinberg College of Arts and Sciences and a faculty fellow at the Institute for Policy Research.

Relatively speaking, humans only recently have lived in such hyper-hygienic environments, he stressed.

I had all this explained to me recently by an immunologist and it is more complicated than it sounds in terms of balancing immune responses....but the overall picture is that we were not designed to live in such sterile conditions. I've heard of a doctor who is quite happy when his toddler licks the conveyor belt at the supermarket checkout.


pieter d said...


a somewhat related activity, with respect to our evolutionary heritage... ;-)




JB said...

Of course, this is very similar to the cause of the great outbreaks of polio in the earlier 20th Century. Scientists couldn't understand why its prevalence was more common in large cities than in rural areas. It was later determined that the large cities were the first to develop a generation of children whose mothers hadn't been exposed to polio because they grew up drinking clean water, not, say, from drinking out of streams. So, the children didn't inherit any resistance to polio, hence the outbreaks in urban populations.

Polio: a debilitating disease that was inadvertently caused by...

clean water sources and better hygiene.

Go figure.


Meredith said...

With H1N1 going around my Purell drenched hubby is driving me nuts. My three year old is going to get what he gets and his immune system will be the better for it. I was vindicated when we went to our Dr. after son came down with an earache. Dr. said her philosophy is to let people fight things off naturally. I loved her for it!

Chris said...

I have friends whose young son was allergic to all sorts of things. It was only after he had chickepox at the age of 3 that everything settled down. It was that infection that challenged his immune system and brought it back into balance.

Chris said...


that is weird stuff!

pieter d said...


Weird stuff indeed!

On a more serious not, if you google allergy/asthma/autoimmune disease and worm/helminth you will find some interesting stuff on the relation between the two.

eg: http://www.ingentaconnect.com/content/bsc/cea/2009/00000039/00000001/art00006

This hypothesis has a nice evolutionary explanation as well.