Nutrients, such as carbohydrate, lipid, protein, vitamins and minerals, are essential for daily activities and growth of our body. However, there are organic compounds in food materials, which do not belong to these categories but have beneficial effect to human health. Foods, which contain these compounds, are defined as functional foods. How do these products look like? What are the molecular mechanisms, which make compounds work in the human body? How does fundamental science interact with modern market nowadays?