A new study offers more evidence that oral health is connected to heart health: Older women who harbor certain bacteria in their mouths might be at increased risk of developing high blood pressure.

The study, which followed 1,200 women for a decade, found that 15 types of mouth bacteria were linked to the odds of developing high blood pressure. Most were tied to an increased risk, but a few types were potentially protective.

The findings do not prove that microbes in the mouth directly influence blood pressure, said Michael LaMonte, a senior author on the study and a research professor at the University at BuffaloState University of New York.

So it’s not yet clear, he said, whether brushing and flossing can help control your blood pressure, too.

But the notion isn’t far-fetched, either. Studies in recent years have found that people with severe gum disease, which is a bacterial infection, tend to have heightened risks of heart disease and high blood pressure.

One theory is that once gum disease sets in, “bad” oral bacteria may get into the systemic circulation and contribute to inflammation in the blood vessels.

Some research also suggests that people with high blood pressure tend to have a different oral microbiome than people with normal blood pressure. The “microbiome” refers to the trillions of bacteria and other microbes that dwell in the human body. Most of those bugs reside in the gut but the mouth has its own large microbial community.

LaMonte’s team wanted to find out whether specific oral bacteria were linked to the risk of developing high blood pressure in the future.

So they used data from 1,215 women who were part of a larger U.S. study called the Women’s Health Initiative. The women, aged 53 to 81 at the outset, underwent a dental exam that included taking a plaque sample. Those samples were analyzed to determine the composition of the oral microbiome.

Over the next decade, 735 women were newly diagnosed with high blood pressure. LaMonte’s team found that 15 oral bacteria were connected to the condition. In most cases, a greater abundance of the bug meant a higher risk of high blood pressure, but five bacteria were tied to a decreased risk.

The findings, published March 2 in the Journal of the American Heart Association, do not answer the question of why.