Nucleic acids are one of the underestimated ingredients in food, especially in the raw or low-processed food products. The paper focuses on discussing conversions in nucleic acids that occur in the human digestive tract, on absorption processes of nucleosides and nucleotides from the gastrointestinal tract; also, the basic steps of their metabolism in the cells of the organism are presented. Digestion products of the nucleic acids are a valuable source of important signalling and precursor molecules. They may also be utilized to form new nucleic acid molecules in the human body. In recent years, low-molecular weight nucleic acids catch most interest, such as non-coding RNA (ncRNA), which are also present in food. It is suggested that the dietary ncRNA can probably impact the regulation of gene expression in the cells of the gastrointestinal tract, and perhaps in other tissues of the consumer. Both the nutritional value and the impact of nucleic acids consumed on the functioning of the genome and transcriptome suggest the need to look into human nutrition in the context of nutrigenomics.