In nutrition sciences, hitherto, nucleic acids were considered to be an insignificant food component. Their nutritional properties are not taken into account in formulating dietary guidelines, even though they are one of the basic ingredients of the food, especially of the raw or low-processed food. They are present mainly in rapidly growing tissue cells as well as in those that have retained their ability to grow and regenerate. In this paper, there are presented literature data on the contents of nucleic acids in different raw materials and food products selected, inclusive of the extraction method used and type of nucleic acid applied. The content of DNA in the selected animal tissues can be up to 100 mg / g of d.m. of the product whereas the content of RNA: up to 87 mg / g of d.m. of the product. In cells, nucleic acids are mainly bound to proteins. It was found that they are not completely degraded during cooking or thermal treatment. In contrast to proteins, they are not ultimately denatured and, hence, they retain, partly, their functional and structural characteristics. Owing to their high molecular weight and hydrophilic properties, macromolecules of nucleic acids are able to structurally, rheologically, and sensorily shape food products; thus, they are relevant for the food-processing technology. In the paper, rheological properties were discussed of nucleic acids as macromolecules that occur in raw materials and food products along with proteins and polysaccharides.