Every person is unique, starting from personality traits all the way to physical characteristics, in the world of sports that uniqueness is the primary goal of sports nutritionists and scientists that study different types of diets (ketogenic, vegetarian, vegand, etc.) and the physical affects of different ergogenic supplements like caffeine and creatine and supplements like vitamins and aminoacids. With the development of society, science and medicine, the key to succeed in the today's world of sports is the proper nutrition and proper guidelines such as: how many food to eat, which food to eat, how much water to drink daiy, which vitamins to take, etc. Through that whole process it is crucial to keep in mind the maintenance of persons health that is forgotten in the fast-paced lifestyle of 21. Century, especially if a person is a professional sportsman. Trends tend to be changing from day to day and new studies are being made that keep telling us the new methods to enhance performance in sports through nutrition. This paper will justify how, and with which methods and guidelines should a professional athlete consider in the area of functional nutrition because functional nutrition is a key to success.