Increasing
concerns about personal cleanliness, especially with children, could be linked
to a reduced the diversity of our microbiomes and increased the prevalence of
inflammatory and stress-related diseases.
New
research gives new weight to the so-called hygiene hypothesis, arguing that
children, in the early years, need to be exposed to dirt (and by implication a
diversity of bacteria) in order suggests to strengthen their immune system, and
that such exposure increases the richness of the human microbiome (the collection
of microbes that reside within the human body.)
The
hygiene
hypothesis
explains that the marked increase in autoimmune and inflammatory diseases since
the 1950s is the direct result of changes in our exposure to microbes in
childhood, which runs in parallel with a reduced exposure to the less than
sanitary conditions. The concept also
relies on
decreasing family sizes, such as having fewer siblings, which results in a
reduced chance of exposure to pathogens. This remains theoretical, although the
ideas are backed by a large number of scientists.
Some
related research, within the broad hygiene field, has been undertaken at University
of Colorado Boulder. Microbiologists and medics have been studying whether the reduced
exposure to infectious agents is coincidental with an increase in
inflammatory-related diseases. The effects of inflammation can lead to a higher
risk of developing stress-related pathologies, like such as post-traumatic
stress disorder (PTSD) and depression.
This
has led to a consideration of whether stress-related disorders can be decreased
(in terms of incidences or severity) by increasing a person’s exposure to
environmental bacteria.
With
this, lead researcher Dr. Christopher Lowry has told
Bioscience Techniques:
“Our approach wasn’t so much to modify the gut microbiome, but to protect the
host from stress-induced microbiome changes.”
The
work has involved looking at a soil bacterium called Mycobacterium vaccae. This
bacterium has been linked to improved moods and lower levels of pain. To see if
the bacteria can reduce stress, the research group vaccinated mice with a
heat-killed preparation prior to exposing them to chronic social stress. It was
observed that the bacterium did promote long-lasting and proactive coping
behavior. In neurological terms, the organism could be exerting an effect on the
serotonergic and microglia systems. This is, therefore, an area worthy of
further exploration.
Posted by Dr. Tim Sandle
