The microbiome can reveal people's life expectancy
Germs in our intestines have been linked to everything from arthritis to autism; now scientists say they can even tell us about our future health. Two new studies show that our microbiome can reveal the presence of many diseases better than our own genes can and may even predict our risk of dying within the next 15 years.
The microbiome reveals several kinds of information
In the first study, researchers reviewed 47 studies examining associations between the collective genomes of intestinal microbes and 13 common diseases. These diseases included schizophrenia, hypertension and asthma, all of which are considered "complex" because they are caused by environmental and genetic factors. They then compared these studies with 24 genome-wide association studies (GWAs), which correlate specific human genetic variants with diseases.
Overall, the genetic signature of intestinal microbes was 20% more effective in distinguishing a healthy person from a sick person than their own genes, the team reported in an article published in bioRxiv. The microbiome was 50% better than the GWA studies at predicting whether a person had colorectal cancer.
Although the author of the study, Braden Tierney, a computer biologist at Harvard Medical School, admits that the analysis is preliminary, he says the work could ultimately benefit people. "We can use both the microbiome and genetics to improve patients' quality of life. The goal, he says, is to identify key markers in both sets of genomes that could help diagnose these complex diseases.
However, microbiology researcher Jeroen Raes of the Centre for Microbiology at VIB-KU Leuven, says scientists don't know as much about the microbiome as they do about how our genes work. So it's 'risky' to compare the two at this stage.
The microbiome has an advantage
However, one of the advantages of the microbiome is that it is influenced by a person's environment: for example, what they eat and how much exercise they do. As such, it may be a better predictor of diseases such as type 2 diabetes, which tend to have large environmental components.
In the second study, researchers looked at the relationship between a person's microbiome and their lifespan. This analysis was based on a Finnish study that has collected health data from thousands of participants since 1972. In 2002, participants gave stool samples that were sequenced 15 years later.
The data show that people with an abundance of Enterobacteriaceae bacteria - a family of potentially infectious bacteria that includes Escherichia coli and Salmonella - are 15% more likely to die within the next 15 years, the team reports in medRxiv.
The link between intestinal bacteria and increased risk of death is found in populations in eastern and western Finland, which have different genetic backgrounds and lifestyles. Dr. Minot says he is impressed with the study, as such long-term analyses are rare and difficult to replicate. "I'd like to see more in the future. »
No one knows why the microbiome is linked to death and disease...
In both of these studies, it is still not known why the microbiome is linked to death and disease. It is possible that microbes may cause disease or shorten a person's lifespan in ways that we do not currently understand. But it's also possible that they just reflect what's going on in the body.
Either way, doctors and scientists who want to help prevent and treat human disease should pay much more attention to the tiny residents in our intestines," says Tierney.
