Benzoic acid in flavored water and glycine use
What it found
In 21 healthy young men, drinking flavored water with benzoic acid led to a fast rise in hippuric acid in urine, and glycine levels did not drop.
The authors say this suggests the body regenerates glycine during detoxification.
What they found
Studies in people
Hippuric acid rise
Urinary hippuric acid increased more than fourfold within one hour of drinking the flavored water, then returned to the same level as before the drink.
Glycine not depleted
Glycine in urine peaked at one hour and stayed abundant during the main detoxification period, suggesting the body was not running out of glycine.
Other metabolites change
After four hours, guanidinoacetic acid and creatine were lower than before the drink, while citric acid and urea were still higher.
Individual differences
The men varied widely in how they processed the benzoic acid, and one man's response at one hour stood out as unusual.
What the authors conclude
“The study disclosed a high degree of inter-individual variation in detoxification of the xenobiotic and revealed metabolic information, indicating that detoxification of benzoic acid through glycine conjugation to hippuric acid does not indicate glycine depletion, but is supplemented by ample glycine regeneration.”
Also in their conclusions
- They conclude that detoxification of benzoic acid through glycine conjugation does not indicate glycine depletion, but is supplemented by ample glycine regeneration.
- They say the observations support the view of maintenance of glycine homeostasis during detoxification.
- They suggest that time-dependent metabolomics investigations using designed interventions can advance understanding of metabolic perturbations.
How it was done
Benzoic acid is widely used as a preservative in food, and some people have raised concerns about what happens when it is consumed in large amounts. The authors wanted to understand how the body handles it, especially whether detoxification uses up glycine.
They gave 21 healthy men, aged 20 to 24, a drink of flavored water containing benzoic acid. They collected urine samples six times over five hours and measured metabolites using nuclear magnetic resonance spectroscopy.
What it can’t tell you
- This was a small study in 21 healthy young men, so the results may not apply to other groups.
- The study only looked at a single dose of benzoic acid in flavored water, not long-term consumption.
- It cannot show whether these metabolic changes have any health effects.
Who paid
- Conflicts
- The authors have declared that no competing interests exist.
- Authors work at
- North-West University (Potchefstroom Campus), South Africa; University of Amsterdam, The Netherlands
The paper
- Title
- Contribution towards a Metabolite Profile of the Detoxification of Benzoic Acid through Glycine Conjugation: An Intervention Study
- Type
- Study
- Evidence
- Studies in people
- Summarised from
- Full text
- Cite
- Irwin C, van Reenen M, Mason S, Mienie LJ, Westerhuis JA, Reinecke CJ (2016). Contribution towards a Metabolite Profile of the Detoxification of Benzoic Acid through Glycine Conjugation: An Intervention Study. PloS one. doi:10.1371/journal.pone.0167309Free full textPubMed 27907139DOI
Summary written 26 Sep 2026. Check it against the paper before it changes what you eat. How we summarise papers · Report an error