Gut bacteria may help prevent asthma in children

The world has seen an explosive rise in asthma over the past three decades. Such a rise in prevalence cannot be only a result of genetic variation and leads us to believe that environmental factors play an important role in this change. There are several possible explanations for this including what we call the “hygiene hypothesis”, or the idea that we now live in an environment that is too clean and we are no longer exposed to the bacteria and germs that earlier generations were exposed to. Another possible explanation is as the world changes and becomes more modern, these environmental changes are affecting our microbiome and the “normal” microbiome is shifting to a new normal.

To better understand why some children are at high risk for becoming asthmatic, scientists in Canada studied the microbiome of 319 children in the Canadian Healthy Infant Longitudinal Development (CHILD) Study. They sequenced fecal samples from the children and found that 4 groups of bacteria that were decreased in prevalence compared to the children without asthma. Bacteria from the genus Lachnospira, Veillonella, Faecalibacterium, and Rothia (FLVR) were at lower levels after 3 months for the children at high risk for asthma however over time, this leveled out and was similar to the children not at risk for asthma.

The study did not identify what exactly caused these differences as there could be several reasons for these differences including antibiotic use, the method in which the child was delivered either vaginally or by C-section, and if the child was breastfed or not. It is also possible and maybe even likely that some of the mother’s behaviors during the pregnancy such as diet could play an important role in the early development of the child’s microbiome.

The next obvious question is what can we do about this? Does this mean that we can now treat children that are deficient of these bacteria and they won’t get asthma? While it sounds simple, we don’t yet know too much about these bacteria and it will be important to better understand the impact his would have on the rest of development. Promising results from this study did show that when mice with low levels of FLVR were treated with probiotic samples of the bacteria, it protected them from getting asthma.

This is a very exciting study that may lead to new diagnostics for asthma and with more research and understanding, allow us to prevent the disease from developing. 

Hand washing dishes may decrease risk of allergies

A study published on Monday by the journal Pediatrics has gotten a lot of press this week because it shows a connection between allergies in children and the method by which parents wash their dishes. Parents, especially new parents, often consider good hygiene as one of the most important factors in raising their new child, but according to the hygiene hypothesis it may be true that too much cleanliness actually negatively affects a young child.  Asthma, eczema, and other autoimmune diseases are becoming more common conditions in children, and each has been linked to the hygiene hypothesis.  Researchers in Sweden reinforced this link when they discovered a possible connection between allergies in children and whether dishes were washed by hand (less clean) or by machine (more clean) in their homes.

 The researchers sent a questionnaire to parents of children aged 7-8 which was filled out by 717 families in Molndal, Sweden and 312 families in Kiruna, Sweden. The questionnaire asked many questions pertaining to the children, including previous symptoms of asthma or eczema, method of washing dishes, and if their food was farm grown or fermented.  When examining the results it is important to remember that all forms of bias cannot be eliminated when doing surveys, because, among other reasons, it is difficult to get a perfectly random sample.

Results of the study showed that there were lower instances of allergies in children whose families washed their dishes mainly by hand rather than by machine. In addition, this effect was amplified if the children ate food that was either fermented or purchased from a farm (both of which should introduce diverse bacteria to the children).  Of course, there were other variables that were not inquired in the questionnaire that are also known to decrease rates of allergies in children, and which may be related to washing dishes by hand, for example a lower socioeconomic status.  Then again, the authors suggest that hand washing dishes may reasonably be responsible for these lower rates of allergies in children of lower socioeconomic status.

So, you may be wondering how exactly this pertains to the microbiome. Hand washing dishes cleans less thoroughly than highly efficient machines, which sounds gross, but the exposure to more microbes when you are young may help develop the microbiome and immune system.  While this study is not perfect, it still shows us that exposure to bacteria is potentially a good thing for the new and developing microbiome.