title: Urinary pharmacokinetics of betalains following consumption of red beet juice in healthy humans.
abstract: The aim of the present pilot study was to characterise the renal elimination of betalains after consumption of red beet juice (RBJ). Six healthy, non-smoking female volunteers were given a single oral dose of either 500 mL of a commercial RBJ containing 362.7 mg of betalains and 500 mL of tap water, respectively, in a sequential manner. Urine was collected in intervals up to 24 h post-dose. Renal excretion of betalains was determined spectrophotometrically and quantified as betanin-equivalents. In addition, the identity of individual compounds was confirmed by HPLC coupled with diode-array detection and positive ion electrospray mass spectrometry, respectively. The amount (mean+/-S.D.) of intact betalains (betanin and isobetanin) recovered in urine was 1001+/-273 microg corresponding to 0.28+/-0.08% of the administered dose. Maximum excretion rates were observed after a median tmax,R of 3.0 h (range 2.5-8.0 h) amounting to 91.7+/-30.1 microg/h. The terminal elimination rate constant (lambdaz) and the corresponding half-life were 0.097+/-0.021 h(-1) and 7.43+/-1.47 h, respectively. Using the lambdaz estimates obtained the expected total betalain amount excreted in urine was 1228+/-291 microg. Based on the results obtained it is assumed that either the bioavailability of the betalains is low or that renal clearance is a minor route of systemic elimination for these compounds. The urinary excretion rates of unmetabolised betalains were fast and appeared to be monoexponential suggesting a one-compartment model. In order to get a more complete picture of the pharmacokinetics and health-promoting properties of red beet betalains, quantitative data on betalain bioavailability should include measurements of unchanged compounds and their corresponding metabolites in plasma, urine and bile.
authors.affiliation: Solvay Pharmaceuticals GmbH, Hans-Boeckler-Allee 20, D-30173 Hannover, Germany. dr_thomas_frank@web.de
authors.forename: Thomas
authors.initials: T
authors.lastname: Frank
authors.forename: Florian Conrad
authors.initials: FC
authors.lastname: Stintzing
authors.forename: Reinhold
authors.initials: R
authors.lastname: Carle
authors.forename: Irmgard
authors.initials: I
authors.lastname: Bitsch
authors.forename: Daniela
authors.initials: D
authors.lastname: Quaas
authors.forename: Gabriele
authors.initials: G
authors.lastname: Strass
authors.forename: Roland
authors.initials: R
authors.lastname: Bitsch
authors.forename: Michael
authors.initials: M
authors.lastname: Netzel
mesh_terms: D000328:Adult; D027461:Beta vulgaris / Q000737:chemistry*; D050859:Betacyanins / Q000493:pharmacokinetics* / Q000652:urine; D001628:Beverages; D001682:Biological Availability; D005260:Female; D006801:Humans
chemical_list: D050859:Betacyanins; C020228:betanin