Are you a parent? Then you may know quite well the dilemma of protection: How much of it is best for your child? For example, the protection from bacteria. Hygiene has led to a better life in all industrialized countries. But it seems that we overdo it. Asthma, allergy and many other diseases have become an ever increasing burden. The immune system of children growing up in a too clean environment is not sufficiently trained and, instead of doing the right job and fight bacteria, it attacks the own body. This is the so-called hygiene hypothesis.
It has gained more support by recent research. For example the stomach bug Helicobacter pylori, known as bad because it can cause peptic ulcer, has also its good traits because it reduces the risk of asthma and allergy. Other good bugs are mycobacteria, so beneficial that there are plans to develop a vaccine against asthma from them.
Even autism is being considered as a potential outcome of a too clean world. With multiple sclerosis (MS), the case is a bit different because it is caused by the Epstein-Barr virus. Only in regions where this virus is less aggressive, exposure to dirt seems to be beneficial against MS.
The larger the families, the lower the risk for children to get asthma or other forms of allergy. Two studies, in Italy and in Israel, have shown this recently, adding further evidence to the hygiene hypothesis: The more siblings, the more dirt and bacteria, and the better the challenge for a growing immune system. While the number of siblings matters, birth order seems to be of no importance. The hygiene hypothesis would predict less allergy in younger siblings, but only if one assumes that the older protect the younger and not vice versa. This is obviously not true, all protect each other.
Another interesting example comes from Finland. The hygiene standard is quite high in this country, and so is the risk of allergy. In Russian Karelia both hygiene and allergy risk are lower.
Learn more about the hygiene hypothesis at Wikipedia ...
This one has been selected by Cindy as a top ten post in her Twelfth Healthy & Fit Family blog carnival at Wisdom of Healing.
(Picture by Joe Thorn @ Flickr)