I wrote about the hygiene hypothesis here at MyAsthmaCentral a few years ago. This is a theory that postulates that our very own cleanliness might make us more susceptible to developing asthma. Another new study has scientists thinking about this hypothesis again.
The recent study by researchers at Tuft University compared the results of previous studies on th subject and, as reported on here at ScienceDaily.com, Americans born of low socioeconomic status in the United States and exposed to such things as cockroaches and mice were more likely to develop asthma than people of similar socioeconomic status in other countries (such as China).
The hygiene hypothesis states that if the immune system is not stimulated by certain pathogens (bacteria, viruses, intestinal worms, etc.) within the first three months of life, the immune system becomes bored and starts to create a defense against otherwise harmless substances such as your own body, dust mites, cockroach urine, molds, pollen, ragweed, etc.
In essence, if your immune system gets bored, certain autoimmune diseases such as asthma, eczema, and arthritis may be the result.
This new study might confirm that pathogens in the air that might help the immune system to mature are probably present in other countries while not present to the same extent in the United States.
The study might also confirm that people from other countries are exposed to more sunlight, which might prove the theory that lack of vitamin D may also be a cause of asthma. Some studies have also confirmed a link between lower levels of vitamin D and asthma.
The study notes the following significant (at least I think they are significant) statistics:
1. They found that U.S.-born children who were exposed to pests were 60 percent more likely to have asthma than U.S.-born children not exposed to pests. Pest exposure had no statistically significant impact on asthma risk in foreign-born children.
2. U.S.-born children with low socioeconomic status were two times more likely to have asthma than U.S.-born children without low socioeconomic status, while low socioeconomic status had no statistically significant effect on asthma risk in foreign-born children.
So while scientists don't yet know exactly what causes one to develop asthma, we have some viable theories. However, it is possible that more than one thing causes asthma, and for this reason we must not get too excited about any one particular theory -- this will keep us open minded.