When bacteria that help convert nitrate to nitrite in the mouth are reduced, blood pressure tends to go up by a small amount (2-3.5 mmHg for systolic and 2-2.2 mmHg for diastolic).

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.

Bacteria in the mouth help regulate blood pressure by converting nitrate to nitrite, which is part of the body's natural blood pressure control system.

When mouth bacteria are disrupted, blood pressure goes up regardless of how it's measured - whether at the doctor's office, at home, or with a 24-hour monitor.

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.

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.