title: The generation of oxygen radicals after drinking of oxygenated water.
abstract: It has been speculated whether ingestion of oxygenated water can lead to an enhanced generation of oxygen radicals. The purpose of three prospective randomized blinded clinical studies was therefore to measure if, when and at which oxygen content in the water,drinking of oxygenated water induces the generation of radicals. Moreover in the fourth prospective,randomized, blinded study possible longterm effects of drinking oxygenated water were examined.
  
  
  METHODS
  Altogether 66 volunteers were drinking 300 ml oxygenated or tap water within 15 minutes. Before drinking, altogether 15 ml of blood from the antecubital vein was collected for determination of ascorbyl radicals with ESR, routine laboratory data (hemoglobin, erythrocytes, hematocrit, leukocytes, thrombocytes, uric acid) and the vitamins A,C,E by HPLC. After drinking the ascorbyl radical measurements were repeated from blood of the antecubital vein. In the longterm study ( fourth study) the volunteers had to undergo the same procedure, as described above, at day 1 and day 21. In the meantime they were drinking per day three times 300 ml either oxygenated water or tap water.
  
  
  RESULTS
  All subjects exhibited normal vitamin levels in all three studies. Concommitantly in the fourth study there was no statistically relevant alteration of vitamin concentrations during the observation period of three weeks in the verum and placebo-group. 30 minutes after drinking oxygenated water the concentration of ascorbyl radicals increased significantly by median 42 % from median 48 to 65 nmol/l. This increase of ascorbyl radicals after 30 minutes was reproducible in all studies. The levels of ascorbyl radicals remained elevated for 60 minutes after drinking and returned to normal after 120 minutes. This increase was independent of the oxygen concentration in the water, beginning at 30 mg oxygen/l. Water containing 15 mg oxygen/l did not lead to an enhanced radical formation. Longterm consumption of oxygenated water attenuated the ascorbyl radical increase normally observed, thus the initial increase of ascorbyl radicals at day 1 could not be observed after day 21, if the subjects were drinking oxygenated water regularly during the observation period.
  
  
  CONCLUSIONS
  Drinking of oxygenated water possibly leads to a time-limited, yet very moderate, systemic generation of radicals. Regular consumption of oxygenated water over a longer period of time seems to attenuate this effect. The mechanisms leading to this effect and adaptation are unknown.
authors.affiliation: Surgical Department, Red Cross Hospital, Nymphenburgerstrasse 163, D-80634 Muenchen, Germany. RK1.chir@t-online.de
authors.forename: M H
authors.initials: MH
authors.lastname: Schoenberg
authors.forename: T C
authors.initials: TC
authors.lastname: Hierl
authors.forename: J
authors.initials: J
authors.lastname: Zhao
authors.forename: N
authors.initials: N
authors.lastname: Wohlgemuth
authors.forename: U A
authors.initials: UA
authors.lastname: Nilsson
mesh_terms: D000328:Adult; D000975:Antioxidants / Q000008:administration & dosage; D005260:Female; D005609:Free Radicals / Q000032:analysis; D006801:Humans; D008297:Male; D008875:Middle Aged; D010100:Oxygen / Q000032:analysis; D011446:Prospective Studies; D017382:Reactive Oxygen Species / Q000032:analysis*; D014881:Water Supply / Q000032:analysis*
chemical_list: D000975:Antioxidants; D005609:Free Radicals; D017382:Reactive Oxygen Species; D010100:Oxygen