Obviously children on farms are exposed to a lot of dirt and animals, both teaming with microorganisms. But I wonder, and it's not discussed, is whether people living on dairy farms are drinking raw milk, which contains lots of microorganisms. After all, the point of milk pasteurization is to kill off bacteria. Will we go back to drinking raw milk to try to prevent allergies? From Science Daily:
Children on dairy farms run one-tenth the risk of developing allergies; Dairy farm exposure also beneficial during pregnancy
Children who live on farms that produce milk run one-tenth the risk of developing allergies as other rural children. According to researchers at The University of Gothenburg in Sweden, pregnant women may benefit from spending time on dairy farms to promote maturation of the fetal and neonatal immune system.
The occurrence of allergic diseases has risen dramatically in Western societies. One frequently cited reason is that children are less exposed to microorganisms and have fewer infections than previous generations, thereby delaying maturation of the immune system.
A study by researchers at Sahlgrenska Academy, University of Gothenburg, monitored children until the age of three to examine maturation of the immune system in relation to allergic disease. All of the children lived in rural areas of the Västra Götaland Region, half of them on farms that produced milk. The study found that children on dairy farms ran a much lower risk of developing allergies than the other children.
"Our study also demonstrated for the first time that delayed maturation of the immune system, specifically B-cells, is a risk factor for development of allergies," says Anna-Carin Lundell, one of the researchers. Children with an allergic disease at the age of 18 and 36 months had a higher percentage of immature B-cells in their blood circulation at birth and during the first month of life.
"We need to identify the specific factors on dairy farms that strengthen protection against allergies and appear to promote maturation of the immune system as early as the fetal stage," Ms. Lundell says.