For this study, the researchers analyzed gut bacteria and cardiac imaging of 8,973 participants without heart disease between the ages of 50-65 from Uppsala and Malmo who were enrolled in the Swedish CArdioPulmonary BioImage Study (SCAPIS).
“We found that oral bacteria, especially species from the Streptococcus genus, are associated with increased occurrence of atherosclerotic plaques in the small arteries of the heart when present in the gut flora. Species from the Streptococcus genus are common causes of pneumonia and infections of the throat, skin and heart valves. We now need to understand whether these bacteria are contributing to atherosclerosis development,” says Tove Fall, Professor in Molecular Epidemiology at the Department of Medical Sciences and the SciLifeLab, Uppsala University, who coordinated the study together with researchers from Lund University.
“The large number of samples with high-quality data from cardiac imaging and gut flora allowed us to identify novel associations. Among our most significant findings, Streptococcus anginosus and S. oralis subsp. oralis were the two strongest ones,” says Sergi Sayols-Baixeras, lead author from Uppsala University.
Some of the species linked to the build-up of fatty deposits in the heart arteries were linked to the levels of the same species in the mouth, this was measured using fecal and saliva samples that were collected from the Malmao Offspring Study and Malmo Offspring Dental Study. These bacteria were also associated with inflammation markers in the blood, and this association remained even after accounting for differences in diet and medications between those who carried the bacteria and those who did not carry the bacteria.
“We have just started to understand how the human host and the bacterial community in the different compartments of the body affect each other. Our study shows worse cardiovascular health in carriers of streptococci in their gut. We now need to investigate if these bacteria are important players in atherosclerosis development,” notes Marju Orho-Melander, Professor of Genetic Epidemiology at Lund University and one of the senior authors of the study.
