We hear more and more in the news about the role of the hygiene hypothesis resulting in less allergic symptoms. As a refresher, this hypothesis suggests that early microbial exposure triggers early immune stimulation that results in immunologic tolerance compared to later exposures that result in allergy and infection from a more inflammatory versus tolerant immune response.
With that in mind, Hesselmar at al. (doi:10.1542/peds.2014-2968) decided to study the common practice of washing dishes to see if the washing dishes by hand (and thus exposing oneself to many more microbes than letting a dishwasher do the washing) resulted in less risk of allergy in those children. The investigators collected data on more than 1000 children age 7-8 years in Sweden and asked them whether their families washed dishes and whether they had signs and symptoms of asthma, eczema, or allergic rhinitis as compared to those families who used a dishwasher.
To our surprise (perhaps yours as well), the families who do hand dishwashing showed much less allergic disease in their children compared to those who used the dishwasher. So—does hand dishwashing mean more microbes to generate immunotolerance at an early age of exposure or not? Is there another explanation for what the authors of this study show nicely in this study?
Drs. Laurence Cheng and Michael Cabana (doi:10.1542/peds.2014-3911) have added an accompanying commentary to this study to try to clean up your concerns about whether or not to buy in or wash away your belief in the hygiene hypothesis. Both the study and commentary dish out some provocative information and opinion, and we welcome your input as well. Just respond directly to this blog, or send us an e-letter or simply comment on our Facebook or Twitter page.