Studying the microbiome includes a focus on the variety of molecules produced by the bacteria—some of which enter the bloodstream and impact health. In addition, compounds that enter our bodies, either dietary or pharmacological, may affect the microbiota. Understanding these interactions is an important step toward understanding the effects of gut microbiota on health.

Now, researchers have found strong links between certain bacteria living in the gut and small molecules found in the blood. The study is based on analyses of both fecal and blood samples from 8,583 participants in the Swedish CArdioPulmonary bioImage Study (SCAPIS).

The findings are published in Nature Communications in the paper, “An online atlas of human plasma metabolite signatures of gut microbiome composition.” In addition, the data have been made freely available to the research community through an online atlas. The aim of the project was to contribute to the expanding knowledge base concerning how gut microbiota influence human health.

Tove Fall, PhD, professor of molecular epidemiology, department of medical sciences, molecular epidemiology, Uppsala University, Sweden.
[Mikael Wallerstedt]
“Earlier studies have shown that the large bacterial community in our digestive system produce a variety of molecules, with the potential to enter the bloodstream and to impact our health. Conversely, medication or dietary components may affect the microbiota composition before entering the circulation. Characterization of these interactions is an important step towards understanding the effects of the gut microbiota on health,” said Tove Fall, PhD, professor of molecular epidemiology at the department of medical sciences and the Science for Life Laboratory, Uppsala University.

Recent technological advances have enabled large-scale genomics characterization of bacterial communities in biological samples. Advances in chemistry have further enabled large simultaneous screens of blood samples in order to measure small molecules. The SCAPIS study represents one of the largest collections in the world of both of these kinds of data. Using deep shotgun metagenomics and ultra-high-performance liquid chromatography linked to mass spectrometry for a detailed characterization of the gut microbiota and plasma metabolome. In doing so, the scientists investigated the links between the gut microbiota and the small molecules in the blood.

Marju Orho-Melander, PhD, professor of genetic epidemiology, Lund University Diabetes Centre (LUDC), department of clinical sciences in Malmö, Lund University. [Petra Olsson]
“The gut microbiota is a universe of its own and we have just started to understand how the human host and the bacterial community affect each other. Our results show that for certain blood metabolites, the bacteria you carry in the gut constitute a strong determinant,” noted Marju Orho-Melander, PhD, professor of genetic epidemiology, Lund University.

The scientific team believes that the breadth of findings may spur the interest of other international groups focusing on gut microbiota and host interactions and has therefore opted to publish all the associations on a public website hosted by SciLife Data Centre in Uppsala.

“The large number of samples containing high-quality data allowed us to identify many novel associations. We have therefore chosen to publish all of our findings in an online open resource for the research community to use for their varying needs,” said Koen Dekkers, PhD, department of physiotherapy, Erasmus MC.