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.

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.

The small blood pressure increase from using the special mouthwash was similar in size to what's known to increase the risk of heart disease and stroke.

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.

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.