If you want to reduce the risk of allergies in children, you should start washing your dishes by hand.
In a very interesting study conducted by Swedish researchers, children who live in households where dishes are cleaned with dishwashers are more likely to develop allergies than those whose dishes were washed by hand.
In this research, the team identified over a thousand kids with ages between 7 and 8, who lived in at least two regions in the country, then talked to their parents. They specifically focused on two things: the amount of fermented or straight-from-farm food they eat and how they washed their dishes.
Upon analysis of the survey, they discovered that eczema and child-related allergies were far less common if the homes cleaned their dishes by hand. The trend didn't change even if they adjusted the results based on the lifestyle and socio-economic status of the families. Hand washing was also shown to reduce the risk of asthma, although the significance was only small.
Further, even children who were small enough to clean through hand washing also had a lower allergy risk. The researchers surmised it had something to do with eating using dishes and cutlery with some traces of bacteria. Using a dishwasher still remains the more efficient way of killing bacteria.
It may seem as if children are better off exposed to bacteria to be at a lesser risk of allergy, but then this is actually the main concept behind the study. It is one of those that tested the hygiene hypothesis, which suggests that children who are exposed to few bacteria are at a higher chance of developing allergies and other diseases later.
This is because the body's immune system isn't given enough chance to acquaint itself to the bacteria and develop the right antibodies to fight them. When something is less familiar to the immune system, it tends to go into a hyperdrive, which then leads to allergy symptoms.
Nevertheless, the researchers agree that their work needs further study.