Scimex: An analysis has found that a western lifestyle diminishes the
variety in our gut microbiome by limiting the transmission of bacteria
between humans. The findings could help develop strategies to tackle the
impact of westernisation, and possibly help reintroduce microbes that
have been eradicated. Bacteria that naturally reside in the gut are important for health,
but recent studies consistently show that a modern lifestyle depletes
the gut's collection of microbes. How lifestyle affects the diversity of
this gut "microbiome" is unclear, but an analysis of the gut
microbiomes of Papua New Guinean and US residents in Cell Reports
now suggests that western lifestyle may diminish the variety of
bacteria in the gastrointestinal tract by limiting their ability to be
transmitted among humans.
"There are several aspects of western
lifestyle that have been hypothesized to alter the gut microbiome and
decrease diversity," explains senior author Jens Walter of the
University of Alberta Department of Agricultural, Food & Nutritional
Science. "These include diet, sanitation, and clinical practices such
as antibiotic use and caesarean sections, but we lack a conceptual
understanding of how our microbiomes are altered."
Walter and his
colleagues compared the fecal bacteria of adults from two rural,
non-industrialized regions in Papua New Guinea with those of US
residents. Papua New Guinea remains one of the least urbanized countries
in the world, and the individuals who were studied live a traditional,
subsistence agriculture-based lifestyle.
The research team found
that Papua New Guineans have microbiomes with greater bacterial
diversity, lower inter-individual variation, and vastly different
compositional profiles compared with US residents. US residents lacked
approximately 50 bacterial types that belonged to the core microbiome in
Papua New Guineans. Their analysis found that the relative importance
of ecological processes that structure the gut microbiota differ in
westernized and non-industrialized societies. Specifically, bacterial
dispersal, or the ability of bacteria to move from individual to
individual, appears to be the dominant process that shapes the
collection of gut bacteria in residents of Papua New Guinea but not
those in US residents.
"These findings suggest that lifestyle
practices that reduce bacterial dispersal—specifically sanitation and
drinking water treatment—might be an important cause of microbiome
alterations," Walter says. "We propose a model based on ecological
theory that fits the data and provides an explanation for the decline of
microbiota diversity in urban-industrialized societies."
The
information obtained in this study has implications for human health,
given that microbiome alterations associated with westernization might
contribute to increases in noncommunicable chronic diseases occurring in
industrialized countries. The investigators noted the importance of
caution when questioning specific modern lifestyle practices, though,
because overall, health and life expectancy is higher in westernized
societies.
"However, we can think about how we can reduce the
collateral damage of modern lifestyle practices on the gut microbiome
without jeopardizing the benefits," says co-author Andrew Greenhill, a
senior lecturer in microbiology at Federation University Australia. "The
findings from this study provide information that could be used to
develop strategies to prevent and redress the impact of westernization
and potentially support the dispersal and transmission of microbes that
have been eradicated."
Additional research is needed to
determine the specific lifestyle and cultural factors that impose
microbiome differences, their relative importance, and the underlying
mechanisms by which microbiomes are altered. In addition, the impact of
bacterial types absent from western populations on human health should
be studied. "Such research might provide important information on the
causes of western lifestyle diseases and a basis for the development of
therapies for their treatment and/or prevention," Walter says.