Ureidopropionic acid, also known as 3-ureidopropanoate or N-carbamoyl-beta-alanine, belongs to the class of organic compounds known as ureas. Ureas are compounds containing two amine groups joined by a carbonyl (C=O) functional group. Ureidopropionic acid is an intermediate in the metabolism of uracil. More specifically, it is a breakdown product of dihydrouracil and is produced by the enzyme dihydropyrimidase. It is further decomposed into beta-alanine via the enzyme beta-ureidopropionase. Ureidopropionic acid is essentially a urea derivative of beta-alanine. High levels of ureidopropionic acid are found in individuals with beta-ureidopropionase (UP) deficiency. Enzyme deficiencies in pyrimidine metabolism are associated with a risk for severe toxicity against the antineoplastic agent 5-fluorouracil. Ureidopropionic acid has been detected, but not quantified in, several different foods, such as gram beans, broccoli, climbing beans, oriental wheat, and mandarin orange (clementine, tangerine). This could make ureidopropionic acid a potential biomarker for the consumption of these foods.