What does a “healthy” microbiome look like? Who is part of a microbiome? How can we quantify and analyze our microbiome?
The Human Microbiome Project (HMP), a $173 million project by the NIH, was initiated to address these questions. It focuses on a comprehensive characterization of the human microbiome and the development of computational tools for the analysis of microbiome data. In 2012, NIH announced the first referenced data of a normal bacterial makeup in healthy individuals. Tissue samples from different body sites of 242 people were collected and sequenced to understand the structure and diversity of the healthy human microbiome. Scientists found that the microbiome contains 360 times more microbial genes than human genes that are involved in vital metabolic functions like digestion or the production of anti-inflammatories. Read the original article published in Nature to find out more.
The American Gut project follows another approach. Rather than carefully selecting test subjects, the founders wanted to involve the national and international public. So far, several thousand people have followed their call. If interested, you can still join the American Gut project!
Earlier this month, American Gut published preliminary results for more than 3,000 participants which described microbial composition and factors that affected the gut habitat, such as age and diet.
Individual Findings – Lone Fighters
Large studies are not necessary to contribute to the understanding of our microflora. Larry Smarr gathered information from blood and stool samples that showed early signs of the disease process, years before the first detectable symptoms of his late onset Crohn’s disease.
And lots of unanswered questions
The research on the human microbiome is just getting started. Although important steps have been made towards defining the human microbiome and its role in diseases, many questions remain to be answered. Are associations with health and disease causal? How can this newly generated knowledge contribute to the development of interventions? In which diseases does the microbiome play a causal role?
A few years earlier, in 2012, an NIH press release announced the definition of a normal bacterial makeup in healthy individuals. This provides a much needed reference in order to study the role of the microbiome in diseases. This research article by Bäckhed et al. elaborates on how understanding the properties of healthy microbiota could contribute to the development of interventions. The results of HMP have implications for other research fields such as epidemiology, as described by Foxman and Rosenthal.
Although science has provided important insights into the role of the microbiome in some diseases, it is still unclear whether these relationships are causal.
Next time you look at a fellow human, pretend to be Neo from The Matrix, only try to see the trillion cells and around 23,000 genes that make up his or her body. Then, take a second look and try to imagine that the microbes within his or her body outnumber the human cells by a factor of 10.
Stay with us to find out in the next post, how scientists deal with this vast amount of information that would blow even Neo’s mind.
What questions would you like to learn more about next?