Nitric oxide is produced by endothelial cells and acts as a vasodilator. It is involved in many processes in the body, including regulation of blood pressure and penile erection. Nitric oxide is synthesized from arginine by the enzyme nitric oxide synthase and acts quickly before being degraded. Supplements can provide benefits but also risks like lowered blood pressure. Foods like peppers and dark chocolate contain compounds that can boost nitric oxide levels.