What causes some people to develop chronic diseases such as rheumatoid arthritis, cancer and metabolic syndrome while others stay healthy? A major clue could be found in their gut microbiome â€” the trillions of microbes living inside the digestive system that regulate various bodily functions.
To utilize the huge population of tiny organisms as a proxy for people’s well-being, Mayo Clinic researchers have developed a Gut Microbiome Health Index. This index distinguishes a healthy microbiome from one that is diseased.
In a new study published in the Sept. 15 issue of Nature Communications, the researchers reveal how their index, composed of a biologically-interpretable mathematical formula, can take a gut microbiome profile from a person’s stool sample to reveal the likelihood of having a disease independent of the clinical diagnosis.
“This discovery advances our understanding of the composition of a healthy gut microbiome that has been long sought after,” says Jaeyun Sung, Ph.D., the corresponding author. “Our index predicts how closely a gut microbiome sample resembles healthy or unhealthy conditions.” Dr. Sung is an assistant professor of surgery, Mayo Clinic College of Medicine and Science, and researcher within the Mayo Clinic Center for Individualized Medicine Microbiome Program.
Gut microbiome’s effects on health
Dr. Sung says the effects of the highly complex microbiome on human health are profound, but the science around how to properly detect whether anything could be wrong, and how to apply the gut microbiome as an indicator of general health is relatively new. What’s known is that the ecosystem of microbes is tied to a host of health benefits, including helping to digest food, regulating metabolism and playing a role in immunity. Still, many questions remain. Recent studies link alterations in the gut microbiome to major chronic illnesses.
“Our index predicts how closely a gut microbiome sample resembles healthy or unhealthy conditions.” – Jaeyun Sung, Ph.D.
Dr. Sung says a lack of analytical tests or algorithm-driven biomarkers hinders the detection of early signs of disease prior to the occurrence of specific, diagnosable symptoms.
For the new study, Dr. Sung and his team analyzed 4,347 publicly available human stool shotgun metagenomes, which allow researchers to extensively sequence all genes in all known organisms present in a stool sample. The samples were pooled across 34 published studies spanning healthy conditions and 12 non-healthy disease conditions.
Nearly 1,700 of the gut microbiome samples were from non-healthy people, that is, those with a clinically diagnosed disease or abnormal body weight based on BMI. Nearly 2,600 samples were from people reported as healthy, that is, with no overt disease or adverse symptoms.
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