Bacteria in the mouth help keep nitrite levels in the blood stable, which is shown by the fact that people with higher nitrite in their saliva also tend to have higher nitrite in their blood.

Using mouthwash that kills bacteria in the mouth makes it harder for the body to convert nitrate to nitrite, which lowers nitrite levels in the blood.

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.

Using mouthwash that kills mouth bacteria leads to higher levels of nitrate in both saliva and blood.

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).

The process where nitrate moves from blood to saliva and gets converted to nitrite by mouth bacteria is important for keeping nitrite levels stable in the blood.