New research suggests that changes to the bacteria inside our bodies may be linked to the growth in allergic diseases. Horizon, a BBC Two science program, covered this topic during a recent episode entitled, “Allergies: Modern Life and Me.” By profiling the experiences of two UK families living with various allergies and asthma, this program tests the hypothesis that bacteria living inside the gut, or a lack thereof, are affecting the development of allergies. (Click here to view the full program, if you’re interested).
Researchers think environmental factors have played a role in the growth of allergic diseases in the last few decades, and daily practices of modern life may be the culprit. High bacterial diversity in the gut has been associated with lower levels of allergic disease, according to several recent studies. For example, researchers have found connections between lower levels of allergies and things like having plants in your house, living on a farm or spending time outside, as these can increase bacterial diversity. Furthermore, the Johns Hopkins Children’s Center reported last month that an estimated one in 10 inner-city children in the United States has an egg, milk or peanut allergy (and researchers contend the actual number could be higher)—a finding that seems to lend support to the bacterial diversity theory.
A Swiss Connection
As I watched the Horizon program on allergies, I was pleased to see Switzerland mentioned, as there’s a prominent researcher here who’s leading some work examining the relationship between bacterial diversity and allergic diseases. Dr. Ben Marsland, an Associate Professor at the University of Lausanne, was interviewed about his work with “germ-free mice.”
While these mice are normal in their appearance, they are free of bacteria, fungi or viruses. Dr. Marsland and his colleagues found that when these mice were exposed to dust mites, they were more prone to an allergic reaction. (Similar results were found recently by a team of researchers led by Dr. Cathryn Nagler at the University of Chicago that exposed germ-free mice to peanut.)
I sent Dr. Marsland an email following the program, to thank him for his research and inquire about current and future work. He passed along three recent publications from his team’s research this year. The citations appear below, if you’re interested in a more detailed description of his findings:
- Gut microbiota metabolism of dietary fiber influences allergic airway disease and hematopoiesis, Nature Medicine; 20, 159–166 (2014).
- Increase in dietary fiber dampens allergic responses in the lung, Nature Medicine; 20, 120–121 (2014).
- Lung microbiota promotes tolerance to allergens in neonates via PD-L1, Nature Medicine; 20, 642–647 (2014).
Dr. Marsland added that his current work includes fundraising for a birth cohort study in Norway involving some basic interventions, such as introducing certain foods at an earlier age. In the future, he hopes his basic research can be translated into effective clinical practices to treat allergic diseases.
Living a Modern Life
During the program, I couldn’t help but think about our own family. How would we fare in a similar experiment like the one conducted with the two families for Horizon? How often do we spend time outside? How many plants do we have in our house? I didn’t have a c-section when either of my sons were born (a vaginal birth results in higher exposure to bacteria). Neither had antibiotics during their first year of life.
I’ve certainly wondered at times if there’s something I could have done to cause my son’s allergies, and this episode of Horizon definitely raised those concerns again. While it may not be possible to determine one specific thing as the root cause, it made me question our current practices. What are some practical ways we can increase bacterial diversity in our lives? I’m already planning to take the boys hiking more often on one of my favorite routes—through the forest and alongside an organic farm with goats, pigs, donkeys and chickens!
For further reading on this topic, check out “Horizon on Allergies,” an excellent post from Michelle’s Blog, written by UK food allergy and intolerance blogger, Michelle Berriedale-Johnson.
Did you watch this episode of Horizon? What did you think? If you have any thoughts or questions to share, please leave a comment below.
Updated: January 24, 2014