title: Comparison of the antioxidant potential in urine, saliva and skin.
abstract: OBJECTIVE
  Free radicals, oxidative stress and their possible consequences for health are becoming increasingly important in modern medicine. Reactive species influence the organism, potentially causing oxidative cell damage. They can be produced by exogenous sources, or be a product of a variety of not only physiological metabolic processes, such as immune response, but also pathological processes. The antioxidant protection system protects the organism from oxidative damage caused by reactions producing an excess of free radicals. The analysis of antioxidant potential (AOP) is therefore becoming increasingly important for the diagnosis of individual vitality.
  
  
  METHODS
  The photochemoluminescence method was used to measure the AOP in urine and saliva, spectrometry was employed to measure the β-carotene content of the skin. In addition, it was investigated whether the AOP(saliva) correlated with the AOPU(urine) (uric-acid independent AOP) as well as the β-carotene content of the skin.
  
  
  RESULTS
  The AOP was significantly higher in urine than in saliva, and both values were significantly positively correlated with each other. However, there was no significant correlation to the β-carotene content of the skin.
  
  
  CONCLUSIONS
  The components of the AOPU(urine) are accumulated over time (night), whereas AOP measurement in saliva is like a snapshot, which explains why AOPU(urine) was significantly higher than AOP(saliva), although the two parameters are correlated with each other. β-carotene is a fat-soluble antioxidant, whereas in our study, only water-soluble antioxidants were determined in the urine. This explains why there is no positive correlation between β-carotene of the skin and AOP.
  
  
  CONCLUSIONS
  For the characterization of the AOP in epidemiological studies, we recommend determining the AOPU(urine) and parallel to this, the β-carotene content of the skin.
authors.affiliation: Institute of Hygiene and Environmental Medicine, University Medicine Greifswald, Germany.
authors.forename: Hicham
authors.initials: H
authors.lastname: Benkhai
authors.forename: Franziska
authors.initials: F
authors.lastname: Köhler
authors.forename: Jürgen
authors.initials: J
authors.lastname: Lademann
authors.forename: Sandra
authors.initials: S
authors.lastname: Lemanski
authors.forename: Manfred
authors.initials: M
authors.lastname: Bornewasser
authors.forename: Elke
authors.initials: E
authors.lastname: Below
authors.forename: Harald
authors.initials: H
authors.lastname: Below
authors.forename: Axel
authors.initials: A
authors.lastname: Kramer