UBC study says asthma caused by overly clean environments

The researchers advised parents to allow their babies to crawl on the floor, and even lick it. Studies involving families from Europe have shown that owning a pet or growing up on a farm decreases asthma risk because kids were exposed to bacteria early in life.

The incidence of asthma has been increasing since the 1950s and the bronchial disease now afflicts up to 20 percent of children in Western countries, the study said.

By sampling the gut microbiome early in life, researchers have shown that four types of commensal microbes, and the metabolites those microbes produced, were present at lower levels in children at high risk of developing asthma when those children were 3 months old.

Usually all infants acquire these four bacteria, nicknamed FLVR (Faecalibacterium, Lachnospira, Veillonella, Rothia), from their environments, but few children do not do so maybe because of their birth circumstances or other factors.

Recent research shows that four types of gut bacteria could help prevent infants from developing asthma.

To explore the association between antibiotic use and asthma risk, Brett Finlay of the University of British Columbia in Vancouver and colleagues collected stool samples from more than 300 babies at 3 months of age. Of the 22 infants who were deemed most at risk for asthma – all of which had not received antibiotics before age one – eight have been diagnosed with the lung disease. “And asthma is really an immune allergic-type reaction in the lungs”.

In a separate experiment, researchers took mice bred to be free from bacteria and introduced either a stool sample from a child at high risk of asthma, or the same sample with additional bacteria.

In the study, the researchers looked at a group of children living in several cities in Canada who were taking part in an ongoing study about asthma.

“Very little is known about these FLVR bacteria and we couldn’t consider that until we’re absolutely sure that it was safe for children”.

Asthma specialist Dr. Mark Greenwald, who is not one of the authors of the study, agrees that there does appear to be a critical developmental window of three months.

The research provides strong support for the “hygiene hypothesis” that suggests over-clean conditions may be making babies more vulnerable to asthma and other allergy disorders. Being able to study a group of children from birth provides “invaluable information” about the presence of specific gut bacteria, and the importance of the timing of exposure to these gut bacteria. “We are starting to discover this massive universe of bacteria”, Turvey says.

However, Turvey said that an outcome of the study would be a vision for the future to prevent the disease.

The study is not definitive proof that editing gut bacteria levels could reduce the risk of asthma, but Finlay’s team did work with mice, breeding them with low FLVR levels, then treating them with FLVR supplements similar to probiotics. This theory suggests that, for a child’s immune system to develop well, it needs to be exposed to a wide variety of bacteria and viruses.