Paul Driessen saw this WSJ discussion of gut flora and asthma. It relates to the hygiene theory that exposure at a young age to allergens reduces hypersensitivity and allergic disease, including asthma.
I would second that motion. Anyone who knows asthmatics and allergies knows that desensitization is one way to reduce the severity of the allergic phenomena.
A very clean environment can cause a hypersensitive child, then adult, goes the theory. Expose yourself to dirt and bacteria and allergens, reduce your sensitivity.
Study Links Asthma to Low Levels of Gut Bacteria in Newborns
Finding could be used to develop diagnostic test, probiotic treatments to prevent disease
By GAUTAM NAIK Sept. 30, 2015 2:00 p.m. ET
Scientists have linked the dearth of four types of gut bacteria to asthma, the respiratory disease that has risen explosively in the past 50 years and now afflicts up to a fifth of children in Western countries.
The researchers discovered that low levels of the bacteria in newborns put them at an increased risk of getting asthma later in life. Infants usually acquire bacteria naturally and are protected. But the increased prevalence of certain events—the use of antibiotics by pregnant women, delivery by caesarean section, urban living and formula feeding—may make it harder for newborns to acquire the needed bacteria, scientists say.
The finding, published Wednesday in the journal Science Translational Medicine, is significant because it could be used to develop a simple, stool-based diagnostic test to predict asthma risk in infants. More ambitiously, it could also guide the development of probiotic treatments to prevent the disease.
Stuart Turvey, pediatric immunologist at the University of British Columbia and co-author of the study, said that while previous research has linked gut microbes to asthma, “our advance was to put a name to some of the bacteria and to emphasize the 100-day window” after birth when newborns crucially need to be exposed to them.
About 300 million people world-wide suffer from asthma, including about 26 million in the U.S. The percentage of the U.S. population with the disease increased from 3.1% in 1980 to 8.4% in 2010, according to the U.S. Centers for Disease Control and Prevention.
Asthma has a genetic component. But science is also making headway in identifying the environmental factors, such as missing microbes, that contribute to the disease. For example, in an elective C-section—a procedure widely practiced in many countries—a newborn misses the initial chance to acquire the mother’s bacteria during labor. Similarly, breast milk may contain favorable microbes that an infant misses when fed formula. Some pregnant women are given antibiotics, which can kill off the beneficial bacteria a newborn might need.
According to one estimate, these modern practices have resulted in the human body losing up to 50% of its original microbial diversity.
“There’s more and more evidence that modern illnesses derive from this loss of microbes—especially early in life,” said Martin Blaser, a microbiologist at the NYU Langone Medical Center, who wasn’t involved in the Science Translational Medicine paper. “The good germs are the ones we get from mom, and those guys are disappearing.”
That appears to be the case with asthma. The latest findings were based on data obtained from the Canadian Healthy Infant Longitudinal Development Study, a large-scale effort to understand the causes of asthma and allergies.
The researchers first looked at clinical data from 319 infants at age 1. They found that 22 of those children showed symptoms of wheezing and atopy, a genetic tendency to develop allergic diseases. By age 3, most of the group of 22 had been diagnosed with asthma.
The scientists then studied stool samples from the group of 22, obtained when the children were 3 months old. Analysis of their gut bacteria revealed lower-than-typical levels of four specific types of bacteria, which were nicknamed FLVR, based on an acronym derived from their scientific names.
This suggested a correlation between FLVR bacteria and the later onset of asthma. An important finding was that there were fewer differences in FLVR levels once the 319 children had reached the age of 1.
“It emphasizes the 100-day window” when it is crucial for newborns to acquire the FLVR bacteria, said Dr. Turvey.
Dr. Turvey’s team confirmed the FLVR-asthma link by doing similar studies on mice. In addition, they showed that newborn mice inoculated with FLVR developed less severe asthma later in life, indicating that the bacteria protected against asthma.
But how does this happen? It could relate to the way a newborn’s newly acquired bacteria influence the development of its immune system. For example, bacteria produce substances known as short-chain fatty acids, or SCFAs, that interact with an infant’s immune cells.
Shifts in SCFAs have previously been associated with the development of food allergies in children. A similar process may be behind asthma. “We found the 22 children in the ‘asthma group’ had lower levels of SCFAs in their stool at three months,’ said Dr. Turvey.
The team is now planning a similar study of 100 Ecuadorean children, to see if the findings hold up in a different population. They will also test whether they need to administer all the FLVR bacteria, or some combination of the four, to reduce asthma risk in mice.
Probiotic For Asthma? Don’t Hold Your Breath
The hygiene hypothesis has some new data. Researchers believe they have evidence that a lack of four bacteria genera early in life leads to a high risk of asthma. However, the study is small and the data is anything but conclusive. Read more.