Functional food is a specific food which fulfills the original aim of being a nutrient and an energy-carrier, but promotes better health and well-being. During the last decades new and healthier foods were designed to reduce the risk of chronic illnesses and conditions such as cardiovascular diseases, osteoporosis, some cancers and obesity. However, functional foods are traditional foods expected to be consumed in the diet, but modified in such a way that promotes better health. In Hungary about 16% of the consumers are interested in buying functional foods for health improvements. Dairy products are most often the target products for reducing the risk of osteoporosis in the elderly and increasing gut function. In recent years the market of plant products, especially of fruits and vegetables was rapidly growing due to their high antioxidant capacity. Enhancement metabolism of polyphenols, and flavonoids formed in fruits and vegetables during traditional breeding and processing is not clarified yet and little is known about the effects of the extensive or intensive breeding and of the most economic harvesting time. The functional food science deals with the scientific substantiation of the influences of specific food components (biological active materials) as well as production and formulation of foods and food ingredients. Some of those components are obtained from natural sources, some others are artificial products of the organic synthesis in the industry. The term „functional foods” has never achieved an official definition, but most experts would agree on its benificially target functions in the body beyond adequate nutritional effects. Moderate consumption of vitamines and antioxidants in the diet carried in functional foods are belived to decrease the risk of chronic diseases. According to some market surveys the market of these designed foods is very large and rapidly expanding because of a growing interest among body-builders and other sportsmen with higher physical activities.