Results from the world’s largest study of the human microbiome

The American Gut Project began in 2012, collecting samples from individuals in 42 countries worldwide.  As part of the project individuals gave fecal, oral and skin samples.  The researchers then used genomic sequencing to analyse a genetic marker called 16SrRNA, a molecule unique to bacteria.  Individuals also gave information on overall health, previous illnesses and dietary and lifestyle practices.

Results suggest that a more diverse plant based diet makes for a more bacterially diverse gut.  The study found individuals who consumed more than 30 different types of plant each week had the most diverse gut bacteria, those same individuals whose microbiome proved to be the most diverse had the lowest resistance to antibiotics (making the antibiotics more effective).  The authors speculate that the individuals whose diet contained the least plants may be eating more meat treated with antibiotics or processed foods.

The project also backed up previous studies that have shown a connection with gut bacteria and mental health.  The project found similar bacteria in the microbiome of those with depression, bipolar disorder, PTSD and schizophrenia, this association was strong regardless of gender, age or geographical location.  These results strengthen the link between mental health and the gut, known as the gut-brain axis (the gut-brain axis is the biochemical signaling that occurs between the gastrointestinal tract and the central nervous system).