This review focuses on the role of dietary factors in the pathogenesis of asthma and chronic obstructive pulmonary disease. Reduced pulmonary function and indicators of airway obstruction have been shown to be strong indicators of mortality; therefore, a link with diet in the pathogenesis of these diseases would have important public health implications. The results of the studies identified in the review suggest that people who have a diet rich in fruit and vegetables have a lower risk of poor respiratory health, and that this may be due to the antioxidant nutrients these foods contain. On the basis of the evidence, it seems justified to promote a healthy diet, high in fruits, vegetables, and whole grain foods and low in alcohol and fatty foods, as set out in existing guidelines for prevention of cardiovascular disease and cancer, to protect respiratory health in both children and adults.