Urine colour change as an indicator of change in daily water intake: a quantitative analysis.
OBJECTIVE
Urine colour (U Col) is simple to measure, differs between low-volume and high-volume drinkers, and is responsive to changes in daily total fluid intake (TFI). However, to date, no study has quantified the relationship between a change in TFI and the resultant change in U Col. This analysis aimed to determine the change in TFI needed to adjust 24-h U Col by 2 shades on an 8-colour scale, and to evaluate whether starting U Col altered the relationship between the change in TFI and change in U Col.


METHODS
We performed a pooled analysis on data from 238 healthy American and European adults (50 % male; age, 28 (sd 6) years; BMI 22.9 (sd 2.6) kg/m(2)), and evaluated the change in TFI, urine volume (U Vol), and specific gravity (U SG) associated with a change in U Col of 2 shades.


RESULTS
The mean [95 % CI] change in TFI and U Vol associated with a decrease in U Col by 2 shades (lighter) was 1110 [914;1306] and 1011 [851;1172] mL/day, respectively, while increasing U Col by 2 shades (darker) required a reduction in TFI and U Vol of -1114 [-885;-1343] and -977 [-787;-1166] mL/day. The change in U Col was accompanied by changes in U SG (lighter urine: -.008 [-.007;-.010]; darker urine: +.008 [.006;.009]). Starting U Col did not significantly impact the TFI change required to modify U Col by 2 shades.


CONCLUSIONS
Our results suggest a quantifiable relationship between a change in daily TFI and the resultant change in U Col, providing individuals with a practical means for evaluating and adjusting hydration behaviours.
Danone Research, RD 128, 91767, Palaiseau Cedex, France. erica.perrier@danone.com.
Erica T
ET
Perrier
Human Performance Laboratory, University of Connecticut, Unit 1110, Storrs, CT, 06269-1110, USA.
Evan C
EC
Johnson
Human Performance Laboratory, University of Connecticut, Unit 1110, Storrs, CT, 06269-1110, USA.
Amy L
AL
McKenzie
Human Performance Laboratory, University of Connecticut, Unit 1110, Storrs, CT, 06269-1110, USA.
Lindsay A
LA
Ellis
Human Performance Laboratory, University of Connecticut, Unit 1110, Storrs, CT, 06269-1110, USA.
Lawrence E
LE
Armstrong
D000328:Adult; D003116:Color; D003681:Dehydration / Q000175:diagnosis; D004326:Drinking; D060766:Drinking Water / Q000008:administration & dosage* / Q000032:analysis*; D005069:Evaluation Studies as Topic; D005260:Female; D006801:Humans; D008019:Life Style; D008297:Male; D012189:Retrospective Studies; D013046:Specific Gravity; D016482:Urinalysis; D014882:Water-Electrolyte Balance; D055815:Young Adult
D060766:Drinking Water
Fluid intake; Hydration biomarkers; Specific gravity; Urine colour