TUESDAY, March 6 (HealthDay News) — Children growing up in the
Amish culture in Switzerland have significantly less asthma and allergies
than Swiss children who didn’t grow up on a farm, according to new
research.
What’s more, the Amish youngsters even have less risk of asthma and
allergy than Swiss children who grew up on non-Amish farms.
The study could support the “hygiene hypothesis” that a too-clean world
is causing today’s urbanized kids to be more sensitive to allergens than
their country cousins.
“In Europe, children living on traditional farms seem to have a very
low prevalence of asthma and allergy,” noted the study’s lead author, Dr.
Mark Holbreich, an allergist with Allergy and Asthma Consultants, in
Indianapolis. In contrast, he said, “in the general population as many as
50 percent will have evidence of allergic sensitivity. They may not have
all the symptoms of allergy, but they will test positive for sensitivity,”
But, “in Swiss children who live on farms, about 25 percent have
allergic sensitivity,” Holbreich said. “In Amish children, it was only 7
percent. There’s something very protective in the Amish children.”
He was scheduled to present the study’s findings Sunday at the annual
meeting of the American Academy of Allergy, Asthma and Immunology (AAAAI)
in Orlando, Fla.
In the study, Holbreich and his colleagues in Switzerland sent out
nearly 29,000 questionnaires to families of children between the ages of 6
and 12 years old. The Amish were given a modified version of the
questionnaire.
A random sample of those who completed the questionnaires was selected
to be given allergy testing.
“The Amish children (138) underwent skin tests,” Holbreich explained,
and “the Swiss farm children and non-farm children had blood tests for
measurement of allergies. For the farm children 3,006 were tested by a
blood test and 10,912 non-farm children were tested.”
The study authors identified asthma cases by asking if a physician had
ever diagnosed the child with asthma, Holbreich said.
Amish children had about half the prevalence of asthma compared to
their non-farm-dwelling counterparts (about 5 percent vs. 11 percent).
Swiss farm children had a rate of asthma of nearly 7 percent.
The rate of allergic sensitization followed similar patterns. Non-farm
children had the highest rates, at about 44 percent, compared with 25
percent in the Swiss farm children and just above 7 percent among the
Amish children.
So, what accounts for this striking difference? Holbreich said the
researchers don’t know for sure, but two factors appeared to be protective
against allergy and asthma in the Amish children. One was that they drink
raw [unpasteurized] milk directly from the cow, and the other was their
exposure to large farm animals from a young age.
“When you have these exposures at a young age, that protection seems to
be lifelong,” said Holbreich.
He cautioned, however, that these finding in no way suggest that people
should start giving their children raw milk, as it can harbor
disease-causing germs.
But, the study’s findings would seem to support the hygiene hypothesis,
which is the idea that allergy and asthma are on the rise in today’s world
because the immune system isn’t exposed to a variety of germs from a young
age. This low level of exposure somehow creates dysfunction in the immune
system, causing it to attack harmless substances, such as pet dander or
peanut proteins.
Two other studies presented at the AAAAI meeting may also provide
support for the hygiene hypothesis. One is a Korean study of about 1,800
children. It found that when antibiotics were given during infancy,
children were more likely to develop allergies and allergic skin disease
(eczema).
The other was a study from Johns Hopkins Hospital that looked at
environmental exposures to chemicals. Researchers found that exposure to
triclosan, a commonly used antibacterial agent found in hand sanitizers
and mouthwashes, was significantly associated with allergies to food and
airborne allergens, such as dust or pollen.
While the Swiss study found an association between Amish farm life and
lower incidence of allergy and asthma, it could not prove a
cause-and-effect relationship.
Dr. Jennifer Appleyard, chief of allergy and immunology at St. Hospital
and Medical Center in Detroit, said one protective factor that the authors
of the Amish study didn’t mention is that the Amish live a fairly secluded
existence and thus, have a fairly protected gene pool. Since genetics are
one suspected aspect in the development of asthma and allergy, it may just
be that the Amish aren’t passing down the genes for those conditions, she
reasoned.
“These are interesting things to think about, but there are so many
confounding factors to look at. I don’t think it’s just Amish living or
farm life. Genes play a role, access to care, environmental exposures.
Maybe it’s not that they’re drinking raw milk, but that they’re drinking
milk without hormones. Or, they’re not getting other environmental
exposures that non-farm children are,” she noted.
Because this research was presented at a medical meeting, the data and
conclusions should be viewed as preliminary until published in a
peer-reviewed journal.
More information
Learn more about allergies from the American Academy of Allergy, Asthma and Immunology.
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