A couple of weeks ago we shared new observations that reveal thumb-sucking and nail biting are associated with less risk for allergy, and talked about how that could happen.
This seems to be a summer of revelations about allergy, because the world’s leading medical journal, The New England Journal of Medicine, has published a major paper peeking behind the curtain of how our bodies develop allergies.
This story about how the body works is especially interesting because all the insights came from a comparison of the experiences of Amish and Hutterite children on their dairy farms.
Both the Amish and Hutterite communities come from German-speaking areas of pastureland in the Alps, and so they are closely related genetically. But their religious practices have kept them isolated from each other, so there are some distinct genetic trends that make each of their communities distinct from each other, and fairly similar within each community.
The punch line is that kids in the Amish communities have remarkably few allergies, no cases of asthma and very little reaction to things in the environment like dust, hay, and pollen. In contrast, kids in the Hutterite community have a very high incidence of allergies, lots of asthma, and lots of reaction to things in the environment, pretty much like most of America.
So, here is an opportunity to see just what is it about modern America, about our communities, that is fueling the raging increases in allergy we all see in friends and families. What is going on Amish farms that keeps their children from developing allergies, does so at a strikingly lower rate?
And how does that difference on Amish farms impact the body to steer it away from developing asthma and allergies?
What is different about an Amish farm?
Incredibly, the distinction about and Amish farm is the lack of machinery and small scale operation. The Amish dairy farm is a single family operation run without any machines. The study measured many details of the dust in Amish homes and the response to elements of this dust in Amish families, and the response to elements of this dust when given to animals. In short, they looked at the dust in the homes of Amish families and found strong evidence for why their kids had dramatically fewer allergies, dramatically.
And the difference could be largely traced to the fact that the family lived in very close proximity to farm animals, worked directly by hand with them, creating a completely different set of exposures to a variety of bacteria than in the mechanized, large-scale Hutterite farm.
Of great import, comparison of the genes for asthma and allergies were essentially the same in the two communities, so differences in these problems could not be explained by differences in these genes across the communities.
What’s in the Amish dust?
There were three big differences in the dust found in Amish and Hutterite homes:
- The Amish homes were 4 times more likely to have cat, dog, dust mite allergens in their dust. A lot more material to react to.
- The Amish homes had more bacteria in their mattresses. A lot more living bacteria in the home.
- The Amish homes had 20 times the level of a highly reactive chemical found on many bacteria, called LPS- see below. A lot more of a highly reactive chemical to react to.
So what is LPS? That chemical is in the category of chemicals that are composed of mixtures of fat and sugar, called a lipopolysaccharides (LPS and also called endotoxin). LPS’s are important chemicals in the outer wall of bacteria, and so they play a very big role in our immune system’s ability to recognize and attack foreign bacteria. LPS’s are especially potent signals for our immune system to launch a major attack against an invading bacteria.
What does it do to drop the chance of developing asthma and allergies?
So, the authors looked at the homes, now they looked at the bodies and blood, to see, what is it about exposure to allergic materials, bacteria, and LPS that so sharply drops the chance a child will develop asthma or allergies.
What they found was two things, these exposures led to changes in:
- The sort of white blood cells circulating in the blood of the Amish children.
- The sort of immune system signalling compounds circulating in the blood of the Amish children.
The white blood cells in the Amish children had far fewer cells associated with allergies, more associated with killing bacteria, and even cells that act to suppress allergic reactions.
The signalling compounds had a clear impact. As noted, LPS, a chemical found in the walls of many bacteria, makes most immune systems go wild with attempts to kill bacteria when it is detected. So the study took immune cells from Amish kids and exposed them to LPS in the lab, which normally would make these cells go wild, but they did not. But LPS did make the Hutterite children’s immune cells react dramatically.
Now, here is perhaps the most dramatic finding: they took dust from Amish and Hutterite homes and, for 4-5 weeks, blew it into the noses of mice who got asthma when exposed to eggs. Impressively, the mice with Amish dust in their nose had very little reaction, and in fact, those dust samples made the mice less reactive. But the Hutterite dust caused the mice to develop allergic white blood cells, lots of asthma.
- The whole study rests on the simple observation that kids on Amish farms had far less asthma and allergies than those on Hutterite farms whose asthma and allergy rate are like the rest of the country, high and getting higher.
- The difference was traceable to the levels of bacteria, allergy irritants, and LPS (the bacterial wall compound that normally causes intense reactions). How curious! The very things we instinctively want to protect our homes from- germs, allergy provoking dust, and highly irritating chemicals from germ walls- dramatically reduce the chance of developing allergies and asthma.
- This finding is directly in line with the hygiene hypothesis which is that allergies and asthma are far more common as we clean up our homes. This was the idea underlying the observation in our recent post that thumb-sucking and nail biting are associated with less allergy and asthma.
- Putting it all together, what does that mean for all of us? It brings us closer, not quite there yet, to the possibility that we may have steps to take that might reduce the chance that our future children might develop asthma and/or allergies, and may even, one day, present the chance to reduce the impact of asthma and allergies on all of us who have them now.
To your health,
Dr. Arthur Lavin