Gut microbes play a crucial role in predicting several health conditions, such as obesity, type 2 diabetes and intestinal bowel diseases. A new study has found that an increase in the number of a particular type of bacteria in the gut increases the risk of coronary atherosclerotic plaques or fatty deposits in arteries.

In the latest study, published in Circulation, researchers from Uppsala and Lund Universities in Sweden evaluated the gut bacteria and cardiac images of 9,000 patients who have no previously known heart conditions.

"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," said Tove Fall from Uppsala University, who coordinated the study.

The research team made use of advancements in technology such as DNA sequencing to identify and compare the samples to known bacteria sequences. The improved imaging techniques helped them to evaluate early changes in the small vessels of the heart.

"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," explained Sergi Sayols-Baixeras, a postdoctoral researcher at Uppsala University and a lead of the study.

After evaluating fecal and saliva samples, researchers found that some of the species of gut bacteria linked to plaque buildup in heart arteries were also associated with the levels of the same species in the mouth. These bacteria were linked with inflammation markers in the blood.

"We have just started to understand how the human host and the bacterial community in the different compartments of the body affect each other," said Marju Orho-Melander, a senior author of the study. "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."