Cytidine (symbol C or Cyd) is a nucleoside molecule that is formed when cytosine is attached to a ribose ring (also known as a ribofuranose) via a β-N1-glycosidic bond.

During digestion, RNA-rich foods are broken-down into ribosyl pyrimidines (cytidine and uridine), which are absorbed intact.

For example, KP-1461 is an anti-HIV agent that works as a viral mutagen,[5] and zebularine exists in E. coli and is being examined for chemotherapy.

Low doses of azacitidine and its analog decitabine have shown results against cancer through epigenetic demethylation.

[6] In addition to its role as a pyrimidine component of RNA, cytidine has been found to control neuronal-glial glutamate cycling, with supplementation decreasing midfrontal/cerebral glutamate/glutamine levels.