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Cleanliness and asthma
Dr. P's Pediatric Journal Club
The study
These Dutch researchers measured levels of dust and bacterial and fungal toxins (potential "allergens") on the living room floors of 700 three-year-olds with allergic moms.
- They classified exposure to these allergens as low, moderate, or high.
- They then followed the kids for 4 years, looking for the development of doctor-diagnosed asthma and allergies.
What the study found
- Children with high exposure to dust and mold at 3 months were significantly less likely to have developed persistent wheezing by four years of age.
- Children with high exposure at 3 months were less likely to wheeze occasionally, but this outcome was not as pronounced (and not statistically significant).
- Children with high exposure at 3 months had lower allergic antibodies (IgE) to one of the fungi.
Dr. P comments.
Why do farmers' kids have fewer allergies and asthma? Why has the prevalence of allergies and asthma increased, even as we conquer ever more infectious diseases? This study adds to the mounting evidence that the exposure early in life to a very clean environment (low on dust and various bacterial and fungal toxins) may play a role.
Here's the theory: The newborn immune system is tolerant and non-allergic to most anything (which is why it sometimes does such a lousy job of fighting off infection). When it is exposed to the usual allergy-causing antigens (such as dust and mold and dogs and cats), the immune system and allergens become lifelong buddies: a long-lasting acceptance and tolerance between them develops.
On the other hand, when an allergy-prone infant is raised in a very clean - almost sterile - environment, the immune system remains unfamiliar with these allergens. Then, when exposed later on, it reacts to them as it would to any alien invader, triggering allergies and/or asthma.
What does this mean?
Sloppy parents of the world stand tall! Your kids may have fewer allergies than will those of your hyper-sanitary peers!
Even if there is a family history of allergies and/or asthma, I think it's too early to actually recommend a little extra dust and mold in your baby's bedroom. But I do hope this information will help parents to overcome their messiness/germ phobia and free you to lighten up on obsessively trying to 'sterilize' your infant's world from all germs and dirt and crud.
Hey, life is messy. This study suggests that maybe that's not such a bad thing after all!
A caveat from Dr. P: It may be true that early exposure to mold and dust and cats, for example, will prevent allergies to them later on (in an already susceptible child). However, once that allergy has been established, the horse is out of the barn: cleanliness and even catlessness, etc. are then very important to prevent significant symptoms.
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Article cited
"Does early indoor microbial exposure reduce the risk of asthma?
The Prevention and Incidence of Asthma and Mite Allergy birth cohort study"
Douwes J, et al. Journal of Allergy and Clinical Immunology, April 2006.
Related Topics: New Clue to Development of Asthma, WebMD Video: Pets & Allergies
Technorati Tags: allergies, asthma, early childhood asthma
7 Comments:
I confess that I've been hawking the hygeine hypothesis for years now. Trouble is, the folks who know more about the immune system than I have been poking holes in it all along.
BTW, a 'corollary' of the hypothesis is that getting sick is good for a baby's immune system. I doubt this. I remind parents getting sick is not a particularly good thing.
best,
Flea
Hi, asthma is an autoimmune disease often related to seasonal rhinitis (hay fever).
There has been a lot of very convincing research at the University of Nottingham demonstrating that the “Clean Hypothesis” may be correct. That a host of autoimmune diseases that are only found in the clean west are caused by growing up and living in an environment that is too clean.
the idea is that we evolved under constant assualt from a variety of parasites and diseases that have been mostly eliminated in the west. Intestinal parasites like hookworm have to down modulate or regulate our immune systems to avoid being destroyed.
Absent this down modulation our now overly strong immune systems attack our own tissues, leading to asthma (as well as Crohn’s Disease and Colitis - University of Iowa).
Check these links out to learn more and fingers crossed for a drug soon.
http://gut.bmjjournals.com/cgi/content/extract/55/1/136
http://www.asthmahookworm.com/
http://www.wellcome.ac.uk/doc_WTX026496.html
Pretty interesting, I thought.
J
Sorry, those links as links...
Wellcome Study
ABC Science Online
Another article about research at Nottingham
Article about asthma New Scientist Article Another Article British Medical Journal on IBS & Crohn's treatment with hookworm University of Iowa
Asthma, in most cases, is manageable through the avoidance of known triggers such as perfumes, smoking, or smog. Keeping the environment that your children live, play, and learn in clean can help to keep it under control. Please visit www.yourchildrenshealth.com for more helpful news and articles about asthma and childhood allergies.
I am terrible a keeping a clean house. I cannot dust because of my allergies and find it better to let it accumulate than to stir it up by cleaning it. My oldest child was diagnosed with asthma before he was 2 and he did not live in hyper-clean environment. He also seems to have many of the same allergies that I have. However, I do agree with the study and feel that we do more harm than good to our children when we keep them too clean.
This is certainly true in my experience. I had a hyper clean mother, who went through the Lysol like crazy -- and I had lots of allergies and health issues as a child. I guess as an overreaction to my upbringing, I am very laid back about cleanliness with my kids and never use antibacterial products with them. We have 2 large golden retrievers, who make it very hard to keep the house clean. My 3 year old has never had any serious illness, no ear infections or allergies and my 2 month old is doing great. I truly believe that exposing kids to the world from a young age is best for their long term health (and is good for my mental health too!)
Personally I have found it best to live in a happy medium and not like Adrian Monk but at the same time not like a slob either. Teaching children cleanliness is not merely for hygiene purposes for most other aspects of life. Don't be lazy, but don't be a neat freak.
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