There is no definitive answer to this question as diets vary greatly between countries and can be influenced by factors such as culture, geography, and access to different types of food. However, countries that are often considered to have some of the healthiest diets include Japan (with a focus on fish, rice, and vegetables), Greece (with an emphasis on fruits, vegetables, whole grains, and olive oil), and Italy (with a diet rich in fresh produce, pasta, and olive oil).