Researchers
at University of California San Diego School of Medicine and collaborators have
published the first major results from the American Gut Project, a
crowdsourced, global citizen science effort. The project, described May 15 in
mSystems, is the largest published study to date of the human microbiome -- the
unique microbial communities that inhabit our bodies.
This
publication provides the largest public reference database of the human gut
microbiome, which may help drive many future microbiome studies. What's more,
according to the research team, the success of the American Gut Project
validates citizen science as a practical model for engaging the public in
research.
Here
are a few observations that have emerged so far:
Diet.
The number of plant types in a person's diet plays a role in the diversity of
his or her gut microbiome -- the number of different types of bacteria living
there. No matter the diet they prescribed to (vegetarian, vegan, etc.),
participants who ate more than 30 different plant types per week (41 people)
had gut microbiomes that were more diverse than those who ate 10 or fewer types
of plants per week (44 people). The gut samples of these two groups also
differed in the types of molecules present.
Antibiotics.
The gut microbiomes of American Gut Project participants who reported that they
took antibiotics in the past month (139 people) were, as predicted, less
diverse than people who reported that they had not taken antibiotics in the
last year (117 people). But, paradoxically, people who had taken antibiotics
recently had significantly greater diversity in the types of chemicals in their
gut samples than those who had not taken antibiotics in the past year.
The
participants who ate more than 30 plants per week also had fewer antibiotic
resistance genes in their gut microbiomes than people who ate 10 or fewer
plants. In other words, the bacteria living in the guts of the plant-lovers had
fewer genes that encode the molecular pumps that help the bacteria avoid
antibiotics. This study didn't address why this might be the case, but the
researchers think it could be because people who eat fewer plants may instead
be eating more meat from antibiotic-treated animals or processed foods with
antibiotics added as a preservative, which may favor the survival of
antibiotic-resistant bacteria.
Mental
health. The American Gut Project researchers also examined the gut microbiomes
of 125 people who reported having a mental health disorder, such as depression,
schizophrenia, post-traumatic stress disorder (PTSD) or bipolar disorder. They
matched each of these participants to individuals who did not have a mental
health disorder, but did have other major factors in common, such as country,
age, gender and body mass index. The team found that people with a mental
disorder had more in common with other people with mental disorders, in terms
of the bacteria makeup of their gut microbiomes, than they did with their
mentally healthy pairs. The observation held true in both U.S. and U.K.
populations, in males and females, and across age groups. In addition, the
research team found some indications that specific bacteria types may be more
common in people with depression than people who do not have the condition.
See:
Posted by Dr. Tim Sandle