Hippuric acid is an acyl glycine present in normal urine. This uremic toxin’s presence increases with consumption of phenol-rich foods (e.g. tea, wine, fruit juice, etc.). Polyphenols are converted into benzoic acid, which then follows the illustrated pathway. Also (as shown), certain foods are rich in benzoic acid - whether naturally, e..g cheese ripening process, whole-grains, or artificially enriched e.g. use of a benzoic acid salt preservative. After ingestion and absorption in the gut, benzoic acid is transported into the hepatic liver cell from blood where it undergoes two metabolic reactions. First, benzoic acid is converted into benzoyl-coenzyme A (BCoA) in a reaction catalysed by acyl-coenzyme A synthetase, then BCoA forms hippuric acid in a conjugation reaction catalysed by the glycine N-acetyltransferase enzyme. A monocarboxylate transporter then exports hippuric acid from the liver to the blood, where it exerts toxic effects. It can reduce blood clotting and, in the kidney, inhibit organic acid secretion. It is associated with phenylketonuria, propionic acidemia, and tyrosinemia I (genetic metabolic disorders).

Metabolism and Physiological Effects of Hippuric Acid References