Researchers studied 55 women (some pregnant, some not, some with high blood pressure, some without) to see how their mouth bacteria and nitrate-processing ability relate to blood pressure changes after eating nitrate-rich food.

Researchers wanted to see if differences in mouth bacteria and nitrate-processing ability explain why some people's blood pressure goes down more than others after eating nitrate-rich food.

Even when people ate a diet low in nitrate, using the special mouthwash still increased their blood pressure, which suggests the effect comes from the body's own nitrate recycling process.

The link between oral bacteria that convert nitrates to nitrites and blood pressure is stronger in people who don't have high blood pressure already.

People with more oral bacteria that convert nitrates to nitrites tend to have lower blood pressure, but only if they don't already have high blood pressure.

When nitrite levels in the blood went down after using mouthwash, blood pressure went up, and this connection was strong enough to be statistically significant.