The paper gives an overview of occurrence in plant materials, the content in food and biological properties of secondary plant products, mainly phytates, protease inhibitors, glucosinolates and phenolic compounds. Due to a quite low intake of these compounds in conventional diets, there are small chances for revealing their antinutritional activity. Accumulated beneficial effect of secondary plant products seems to result from the wholesome effect of increased consumption of vegetables and fruit, that – in turn – decreases the risk of neoplasms and coronary diseases.