Dear student,
Food contains nucleic acid. It remains unchanged until it reaches the small intestine. There it is acted upon by Pancreatic enzyme nuclease first, which breaks it down to dinucleotides. These dinucleotides are further broken down to mononucleotides by intestinal enzyme nucleotidases. Then, enzyme nucleosidase separates the free purine and pyrimidine bases, as well as the ribose or deoxyribose sugars from nucleosides. These are then absorbed into the intestinal cells.
Regards.