The Effect of a High Intake of Tartaric Acid on Urinary and Plasma Oxalate

Abstract

The metabolism of tartaric acid in man has not yet been fully elucidated. Finkle¹ concluded from his studies that parenteral tartrate appears unchanged in the urine. Studies by Chadwick et al² clearly demonstrated partial metabolism of sodium tartrate to C0₂ over 8 h after intravenous administration of ¹⁴C-labelled DL-tartrate. Intestinal bacteria, they found, metabolized both D-and L-tartrate. After oral ingestion, as much as 46% of tartrate was converted to C0₂ and only 12% excreted unchanged in the urine. Other metabolites of tartrate in man have not yet been identified. Whether or not oxalic acid may be an end-product of tartrate catabolism was investigated by Chadwick et al². They concluded that no significant formation of oxalate occurred. However, oxalate excretion in only one subject was studied. Kun and Hernandez³ reported that the mitochondria of several animal tissues contain an enzyme system capable of oxidizing meso or D-tartrate. They proposed formation of glyoxylate from tartrate as follows: D (−) or Meso Tartrate + NAD⁺→Dihydroxyfumarate →^{Mg 2+} Glyoxylate Glyoxylate is readily converted to oxalate in vivo. Tartaric acid L(+), is present in many fruits and is widely used as a constituent of effervescent drinks. The Redoxon tablet preparation of ascorbic acid contains 800 mg of L(+) tartaric acid/g of ascorbic acid. A knowledge of the end-products of tartrate metabolism is therefore of considerable interest and in the present study its possible metabolism to oxalate was investigated.