One of the many benefits of exercise is its ability to lower blood pressure, but regular mouthwash users may be greatly reducing that effect. A recent study found antibacterial mouthwash could diminish the blood pressurelowering eff ect of exercise by as much as 60 per cent.1 That’s because it can kill off bacteria that produce nitrite, a molecule that enhances the production of nitric oxide which, in turn, increases the diameter of the blood vessels – increasing blood flow and reducing blood pressure.