As scientists catalog the trillions of bacteria found in every nook and cranny of the human body, a new look by the University of Michigan shows wide variation in the types of bacteria found in healthy people. Based on their findings in Nature, there is no single healthy microbiome. Rather each person harbors a unique and varied collection of bacteria that’s the result of life history as well as their interactions with the environment, diet and medication use.
“Understanding the diversity of community types and the mechanisms that result in an individual having a particular type or changing types will allow us to use their community type to assess disease,” says lead study author Patrick D. Schloss, Ph.D., associate professor of microbiology and immunology at the U-M Medical School.
Beneficial bacteria is the gut are known to attack pathogens, manufacture vitamins and even act as anti-cancer agents. Recent research has strengthened the scientific understanding that the microbes that live in your gut may affect what goes on in your body.
University of Michigan Host Microbiome Initiative (HMI) is designed to foster research on the role of microbes in human health and disease.
The initiative will build upon long-standing strengths in microbiology, microbial pathogenesis, immunology and clinical medicine. The HMI will leverage recent developments in technology and national initiatives such as the National Institutes of Health’s Human Microbiome Project to accelerate our understanding of how communities of microbes interact with their host.
“Co-resident microbes are our ‘old friends’ that help us adapt to different lifestyles and environments”, says Amanda Henry, leader of the Max Planck Research Group on Plant Foods in Hominin Dietary Ecology. “Through this analysis of gut microbiota, we have increased our knowledge of human-microbiome adaptations to life.”
Trillions of bacteria are hostile and can cause disease, while many others are friendly and have established a symbiotic, mutually beneficial relationship with us over the millennia. These friendly bacteria have also been referred to as "probiotics" and are being used increasingly by mainstream clinicians for both preventive and therapeutic purposes.
The Human Microbiome Project is the movement to understand how changes in the microbiome are associated with changes in health.
Additional findings in today’s study reveal bacteria can be grouped into community types that are predictive of each other.
“What was unexpected was that it was possible to predict the type of community a person had in their gastrointestinal track based on the community in their mouth,” Schloss explains. “This was possible even though the types of bacteria are very different in the two sites.”
More than 200 scientists in the HMP consortium spent five years analyzing samples from nearly 300 healthy adults. The samples came from 18 different places on their bodies, including their mouths, noses, guts, behind each ear and inside each elbow.
Schloss and co-author Tao Ding, Ph.D, revealed it is possible to associate a limited amount of data from the subjects with their community type. Whether a person was breastfed was associated with their gut community type, level of education was associated with the vaginal community type, and one’s gender affected several body types as well.
Medication, specifically antibiotics can cause changes in gastrointestinal tract microbes and alter immune system responses, making people more sensitive to common allergens, said a previous University of Michigan Health System study.
Microbes are thought to encode more than 3 million genes in the body, and this complexity of bugs may also be responsible for immune dysfunction that begins with a "failure to communicate" in the human gut, scientists say.
“What our data shows is that just because a person’s microbiome is different doesn’t make it unhealthy,” says Schloss. “It demonstrates there’s more to learn about the factors that cause one’s microbiome to change.”
Understanding why community types change will be useful in developing therapies that can alter one’s community type using pre- and probiotics.
April McCarthy is a community journalist playing an active role reporting and analyzing world events to advance our health and eco-friendly initiatives.