Benzoate, was one of the compounds first found to be elevated in urine from patients with intestinal bacterial overgrowth of various origins. Many people with intestinal bacterial overgrowth resulting from cystic fibrosis, unclassified enteritis, celiac disease, or short bowel syndrome have elevated benzoate along with varying degrees of elevated phenylacetate, p-hydroxybenzoate, and p-hydroxyphenylacetate.

Benzoic acid, a common food component used as a preservative in packaged foods such as pickles and lunch meats, also occurs naturally in cranberries and other fruits, a factor to take into account when interpreting elevated hippurate levels in urine. Whether the source is dietary intake or jejunal bacterial metabolism, benzoate should be rapidly converted to hippurate by conjugation with glycine.

What is Hippurate?

Hippurate is produced by the conjugation of Benzoate and glycine, found as a normal component in urine as a metabolite of aromatic compounds from food. Increased urine hippuric acid content may have antibacterial effects.

What is Glycine?

Glycine is an amino acid serving several important purposes within the body, including:

- Detoxification,

- DNA formation,

- The synthesis of hemoglobin,

- and as a part of brain neurotransmission pathways.

- In the liver, glycine helps to convert many potentially harmful substances, including toxic materials such as benzoic acid (benzoate) into harmless forms.

References:
– van der Heiden C, Wauters EA, Duran M, et al. Gas chromatographic analysis of urinary
tyrosine and phenylalanine metabolites in patients with gastrointestinal disorders. Clin Chim Acta, 1971;34:289-296.
– Temellini A, Mogavero S, Giulianotti PC, et al. Conjugation of benzoic acid with glycine in human liver and kidney: a study on the interindividual variability. Xenobiotica 1993;23:1427-1433.