Mouthwash destroys bacteria in your mouth that can contribute to the growth of cavities and other dental diseases. Unfortunately, mouthwash kills all types of bacteria, including the beneficial ones that help produce nitric oxide. Special bacteria in the mouth convert nitrate to nitric oxide. In fact, humans cannot produce nitric oxide from nitrate without these bacteria. Research has shown that mouthwash kills the oral bacteria needed to produce nitric oxide for up to 12 hours. This leads to a decrease in nitric oxide production and, in some instances, an increase in blood pressure. Nitric oxide (not nitrogen oxide or nitrous oxide) is produced by nearly every type of cell in the human body and one of the most important molecules for blood vessel health. L Arginine is a precursor for nitric oxide. It's a vasodilator, meaning it relaxes the inner muscles of your blood vessels, causing the vessels to widen. In this way, nitric oxide increases blood flow and lowers blood pressure. The detrimental effects of mouthwash on nitric oxide production may even contribute to the development of diabetes, which is characterized by malfunctions in insulin production or action. This is because nitric oxide also regulates insulin, which helps cells utilize the energy obtained from food after it’s digested. Without nitric oxide, insulin cannot work properly. One study found that people who used mouthwash at least twice daily were 65% more likely to develop diabetes than those who never used mouthwash. Therefore, to maintain adequate nitric oxide production, it’s best to use mouthwash sparingly.