title: Quantification of chromatographic effects of vitamin B supplementation in urine and implications for hydration assessment.
abstract: Changes in body water elicit reflex adjustments at the kidney, thus maintaining fluid volume homeostasis. These renal adjustments change the concentration and color of urine, variables that can, in turn, be used as biomarkers of hydration status. It has been suggested that vitamin supplementation alters urine color; it is unclear whether any such alteration would confound hydration assessment via colorimetric evaluation. We tested the hypothesis that overnight vitamin B2 and/or B12 supplementation alters urine color as a marker of hydration status. Thirty healthy volunteers were monitored during a 3-day euhydrated baseline, confirmed via first morning nude body mass, urine specific gravity, and urine osmolality. Volunteers then randomly received B2 (n = 10), B12 (n = 10), or B2 + B12 (n = 10) at ∼200 × recommended dietary allowance. Euhydration was verified on trial days (two of the following: body mass ± 1.0% of the mean of visits 1-3, urine specific gravity < 1.02, urine osmolality < 700 mmol/kg). Vitamin purity and urinary B2 concentration ([B2]) and [B12] were quantified via ultraperformance liquid chromatography. Two independent observers assessed urine color using an eight-point standardized color chart. Following supplementation, urinary [B2] was elevated; however, urine color was not different between nonsupplemented and supplemented trials. For example, in the B2 trial, urinary [B2] increased from 8.6 × 10(4) ± 7.7 × 10(4) to 5.7 × 10(6) ± 5.3 × 10(6) nmol/l (P < 0.05), and urine color went from 4 ± 1 to 5 ± 1 (P > 0.05). Both conditions met the euhydrated color classification. We conclude that a large overnight dose of vitamins B2 and B12 does not confound assessment of euhydrated status via urine color.
authors.affiliation: US Army Research Institute of Environmental Medicine, Natick, Massachusetts; and Robert.W.Kenefick.civ@mail.mil.
authors.forename: Robert W
authors.initials: RW
authors.lastname: Kenefick
authors.affiliation: US Army Research Institute of Environmental Medicine, Natick, Massachusetts; and.
authors.forename: K R
authors.initials: KR
authors.lastname: Heavens
authors.affiliation: US Army Center for Environmental Health Research, Fort Detrick, Maryland.
authors.forename: W E
authors.initials: WE
authors.lastname: Dennis
authors.affiliation: US Army Research Institute of Environmental Medicine, Natick, Massachusetts; and.
authors.forename: E M
authors.initials: EM
authors.lastname: Caruso
authors.affiliation: US Army Research Institute of Environmental Medicine, Natick, Massachusetts; and.
authors.forename: K I
authors.initials: KI
authors.lastname: Guerriere
authors.affiliation: US Army Research Institute of Environmental Medicine, Natick, Massachusetts; and.
authors.forename: N
authors.initials: N
authors.lastname: Charkoudian
authors.affiliation: US Army Research Institute of Environmental Medicine, Natick, Massachusetts; and.
authors.forename: S N
authors.initials: SN
authors.lastname: Cheuvront
mesh_terms: D000328:Adult; D015415:Biomarkers / Q000652:urine*; D015992:Body Mass Index; D001834:Body Water / Q000502:physiology; D003116:Color; D003681:Dehydration / Q000378:metabolism / Q000503:physiopathology* / Q000652:urine*; D019587:Dietary Supplements; D005260:Female; D006801:Humans; D008297:Male; D012256:Riboflavin / Q000652:urine*; D014556:Urine / Q000737:chemistry*; D014805:Vitamin B 12 / Q000652:urine*; D014882:Water-Electrolyte Balance / Q000502:physiology
chemical_list: D015415:Biomarkers; D014805:Vitamin B 12; D012256:Riboflavin
keywords: hydration assessment; urine color; vitamin supplementation