Michael Mosley speaks to Professor Jon Lundberg, an expert in nitric oxide who discovered its surprising benefits for lung function and overall health. They discuss the benefits of breathing through your nose, including improved lung function, memory, and oral health. They also explore the role of nitric oxide in boosting oxygen uptake and fighting off infections. Techniques to transition from mouth breathing to nose breathing are shared, along with the positive effects of nose breathing on gum health, oxygen intake, and the immune system.