While sometimes a tedious task, washing dishes by hand may reduce the risk of allergic disease development in children compared to using a dishwasher. It has been previously proposed that risk of allergic disease development could be reduced via immune stimulation by early microbial exposure, creating an allergy-protective effect and a dose-response effect.

Published in the journal Pediatrics, a new study surveyed parents/guardians of 1,029 children ages 7–8 living in Sweden on dishwashing habits (hand or machine), consumption of fermented food (sauerkraut, fermented cucumber, or other fermented foodstuffs), and consumption of food from farms (hens’ eggs, meat, or unpasteurized milk directly from farm). The parents/guardians were also asked if their child had received a confirmed diagnosis of eczema, asthma, allergic rhinoconjunctivitis, or food allergy.

,p>History of eczema in children was reported by 23% of parents who used hand dishwashing vs. 38% of those who mainly used machine dishwashing and asthma in 1.7% and 7.3%, respectively. The difference was not statistically significant for ARC. While eating fermented food and buying food directly from farms appeared to have a protective effect, it is only statistically significant for total allergy. The associations between hand dishwashing and allergic diseases was statistically significant for eczema and total allergy, but had borderline significance for asthma.

Although there is not presently strong support for these lifestyle factors in allergy prevention, the authors add that these practices are already common and often regarded as harmless.