Raised on rural farms in north Indiana, a new study finds Amish children show significantly lower rates of allergies and asthma than normal children.

The children had even lower rates than Swiss farm children, a group long known to be relatively free from allergies.

The study authors could not determine what about growing up on farms, and Amish farms in particular, resulted in the minimal rates of allergies.

It has been a long observed but little understood phenomenon, the “farm effect,” which shows low allergy and asthma rates among kids raised on farms.

Most of the studies observe farms in Europe, but after noticing that most of his North American Amish patients did not have allergies, the study doctor teamed with colleagues to conduct the study.

Amish families typically farm and live using methods from the 1800s, often not owning cars, televisions or even electricity.

The research found that only five per cent of Amish children were diagnosed with asthma, compared to a rate of 11.2 per cent in other Swiss children.

Along the same lines, of the Amish children tested for allergies, only seven per cent showed a positive response to a skin-prick test.

Nearly 44 per cent of the other Swiss children had a positive test, meanwhile.

While the study could not explain why, most theories argue early exposure to diverse allergens can cause the immune system to adapt positively toward them.