What does asthma have to do with farm animals — or food?

livestockasthmaWhen government officials hear the words "backyard livestock," they tend to worry about disease outbreaks and sanitation crises. And for good reason, as improperly managed animals — including dogs and cats — can be the source of all sorts of public health problems. When it comes to asthma, however, recent science is hinting that early childhood exposure to domestic animals can actually protect against the chronic condition, so well-cared-for backyard animals like chickens or miniature goats could actually have an additional, unexpected benefit.

I learned about this intriguing idea on Quest, a science program produced by KQED in San Francisco (with all programs available for on-line viewing). One of the segments is all about asthma: what it does, how to prevent it, and why the incidence has been rising rapidly in recent years (they state that rates more than doubled in small children in the U.S. between 1980 and 1994). Asthma's underlying cause and triggers are still a mystery — as yet, no one has found the "magic allergen" or markers of genetic predisposition — and so researchers are looking at diet, stress, air pollution, early exposure to allergens and more. (For more information, consult a series of papers in Environmental Health Perspectives examined how the environmental influences asthma, and a recent study from the Health Effects Insitute found a causal relationship between traffic-related air pollution and exacerbation of asthma in children.)

One thing that stands out is that asthma rates have been rising in industrialized societies like the U.S., Western Europe, Australia and Japan. And one thing that these places have in common is more time spent inside, more concrete, more cars, fewer farms, and less exposure to the natural world.

This leads us to one of the intriguing ideas about asthma and other allergies (and even diseases related to chronic inflammation, as New Scientist reports): the "hygiene hypothesis." This hypothesis, first proposed a few decades ago, suggests that as our environments become cleaner and we spend less time around "dirty" things like animals and the natural world, our bodies aren't being exposed to enough microorganisms and therefore don't develop the proper defenses (or, in the case of asthma, don't overreact to external allergens).

The program mentions a study of children in Germany, Switzerland and Austria that supports the hypothesis. In rural communities, researchers found lower asthma rates in children whose sleeping quarters were close to the livestock stables than those who lived in town, away from the animals. One possible explanation for the difference is that exposure to the microbes found in manure and stables protects a child from developing asthma by causing favorable changes to their immune system. (Although the exact study is not mentioned in the Quest piece, I suspect it is one in the New England Journal of Medicine that concludes "Endotoxin levels in samples of dust from the child's mattress were inversely related to the occurrence of hay fever, atopic asthma, and atopic sensitization.")

The hygiene hypothesis and its connection to livestock are still only hypothetical at this time — there are a number of confounding results, like higher asthma rates among low-income children in allergen-laden urban areas and the link between asthma and exposure to tobacco smoke at a very early age. If it turns out that early exposure to livestock reduces the chance of developing asthma, it could be a benefit above and beyond the urban farming's main benefits of good, clean and local food.

Editor's note: Robyn O'Brien's fantastic 2009 book, "The Unhealthy Truth: How Our Food Is Making Us Sick - And What We Can Do About It," offers an alternative to the hygiene hypothesis when it comes to asthma. (Alas, "The Unhealthy Truth" is one of many sitting in a teetering pile Ethicurean headquarters that got read and should have been reviewed by now … and that we continue to hope will someday still be.) O'Brien talks to Harvard Medical School pediatrician David Ludwig, author of "Ending the Food Fight: Guide Your Child to a Healthy Weight in a Fast Food/ Fake Food World," who believes that it is the U.S. dietary shift toward fake food that has sabotaged our immune systems, both by subjecting us to an onslaught of evolutionarily-novel compounds in the form of artificial and/or genetically modified ingredients, and by depriving us of the essential nutrients to mount a defense. In this fake-food hypothesis, farm kids and those whose parents keep urban livestock would have lower asthma and food-allergy rates because they grow up in a family food culture less dependent on processed food.

Photoillustration: Livestock breeds image created by W. Layman in 1911, archived at Michigan State University Museum.

6 Responsesto “What does asthma have to do with farm animals — or food?”

  1. urban backyard farmer says:

    Hmmm, my 7 year old son has asthma, the only one out of my 6 children to ever have it.
    He started when he was just under a year old and has had attacks so severe he has been hospitalized more than once.
    He was breastfed.
    I raise chickens  for eggs and meat and we have goats for pets, milk and the by products of that milk.
    I buy local, grass fed, organically raised beef.
    I grow many of our vegetables (organically) and I buy what I don't grow at the farmer's markets.
    I bake my own bread,  peanut butter, jam, granola, soup etc.
    I keep bees, so we have fresh honey available at all times.
    My son has always had animals of some type and has always had a healthy diet.
    He started asthma very young, before most environmental or dietary issues could make a difference.
    He had an RSV infection when he was 6 months old and I was told that could be the reason for his asthama, it can leave you prone to this condition.
    He was also the  only one of my 6 children to ever have that infection.
    True or not, who will know for sure.
    However I do not believe it could have been caused by food in anyway.
    Just saying, there are other reasons to consider.

  2. Sandy says:

    UBF:  I'd say, you've made a good case for homemade, real food having protected your *other* kids from asthma . . . you do note that they didn't have the infection that afflicted the one asthmatic child.

  3. urban backyard farmer -- I hope you didn't interpret my post and the editor's note to say that exposure to animals or eating only natural foods is 100% preventative of asthma. There is no certainty around the subject -- scientists and doctors still don't know exactly what causes asthma, and it could be any number of things, or some combination, including genetic factors, or perhaps even the RSV infection. And when it comes to animals and asthma, researchers have found some protective effect, but I don't think they know exactly what is going on, i.e., which chemicals or biological species are interacting with the body or when in life the exposure is important.

  4. Jen says:

    The WNYC program "Radio Lab" did a fascinating, hilarious podcast on this very topic. It's called "Parasites," and I'm sure is available on their Web site.

  5. Jen -- thanks letting us know about the Radiolab program on parasites. It was one of my favorite episodes from that incredible program, so much so that it inspired me to write a post on parasites at my Mental Masala blog. In terms of asthma, there is one segment that is particularly relevant, the one about a man who traveled to Africa to intentionally infect himself with a hookworm parasite in a desperate attempt to cure his severe allergies. He says it worked and now he runs a hookworm infection service. Here is the Radiolab page on the episode, which allows you to stream the program or download the entire program in MP3 format.

  6. I developed asthmas at 2 yrs. Both of my children developed asthma at 2 yrs. Neither of my siblings have ever had asthma. I was a sick kid....tonsillitis and on lots of ABX. I don't remember my sisters being very sickly. My kids were sickly, esp our son with chronic ear infections and treated with lots of ABX.  Our daughter didn't show any signs of asthma until the night we moved into our new house. We spent more time in the ER than anywhere else from severe asthma attacks. We went the route of allergy shots until she was 5ish. She was on lots of meds including ABX. Then we took her out of school and homeschooled at age 7 and NO more asthma. It disappeared. As well as her med's. I continued to have asthma into my 40's until I stopped eating foods that I was intolerant to.  Of which included pasteurized milk and wheat gluten. My asthma was gone for the first time in my life. I healed my leaky gut and can now drink raw milk and fermented gluten. However this past year has been a bad year for my asthma again. I've narrowed it down to mold. It has been a particularly wet year in the Mid-Atlantic region and mornings and nights are very bad for me hacking up a lung or two. Once the ground is frozen over with snow, I'm fine. I have always been "allergic" to different animals. In the past year I bought 2 Jersey cows, and we have 18 chickens and a dog. At first I was "allergic" to the cows with asthma symptoms and sneezing. After my daily exposure I no longer have any reaction to them or hay and straw....the dust in the hay does stir things up for me though. I know that what I wrote is fragmented....it's just a rundown of facts that I could remember. What I do believe about asthma now that I am 52 is that it is related to many different factors. 1)environmental toxins (our new home) 2) food intolerances due to leaky gut 3) natural toxins(mold) 4) lack of exposure 5) drug connection-possibly ABX. I am thrilled though to hear of all the children being "healed" with the consumption of raw dairy. Just my thoughts. Maybe I should get a hold of a hookworm!! ;D