Estimated net acid excretion inversely correlates with urine pH in vegans, lacto-ovo vegetarians, and omnivores.
OBJECTIVE
Diet affects urine pH and acid-base balance. Both excess acid/alkaline ash (EAA) and estimated net acid excretion (NAE) calculations have been used to estimate the effects of diet on urine pH. This study's goal was to determine if free-living vegans, lacto-ovo vegetarians, and omnivores have increasingly acidic urine, and to assess the ability of EAA and estimated NAE calculations to predict urine pH.


METHODS
This study used a cross-sectional design.


METHODS
This study assessed urine samples of 10 vegan, 16 lacto-ovo vegetarian, and 16 healthy omnivorous women in the Boston metropolitan area. Six 3-day food records from each dietary group were analyzed for EAA content and estimated NAE, and correlations with measured urine pH were calculated.


RESULTS
The mean (+/- SD) urine pH was 6.15 +/- 0.40 for vegans, 5.90 +/- 0.36 for lacto-ovo vegetarians, and 5.74 +/- 0.21 for omnivores (analysis of variance, P = .013). Calculated EAA values were not significantly different among the three groups, whereas mean estimated NAE values were significantly different: 17.3 +/- 14.5 mEq/day for vegans, 31.3 +/- 8.5 mEq/day for lacto-ovo vegetarians, and 42.6 +/- 13.2 mEq/day for omnivores (analysis of variance, P = .01). The average deattenuated correlation between urine pH and EAA was 0.333; this value was -0.768 for estimated NAE and urine pH, with a regression equation of pH = 6.33 - 0.014 NAE (P = .02, r = -0.54).


CONCLUSIONS
Habitual diet and estimated NAE calculations indicate the probable ranking of urine pH by dietary groups, and may be used to determine the likely acid-base status of an individual; EAA calculations were not predictive of urine pH.
Ausman
Lynne M
LM
Gerald J. and Dorothy R. Friedman School of Nutrition Science and Policy, Tufts University, Boston, Massachusetts 02111, USA. lynne.ausman@tufts.edu
Oliver
Lauren M
LM
Goldin
Barry R
BR
Woods
Margo N
MN
Gorbach
Sherwood L
SL
Dwyer
Johanna T
JT
D000136:Acid-Base Equilibrium / Q000502:physiology*; D000143:Acids / Q000652:urine; D000328:Adult; D000704:Analysis of Variance; D003404:Creatinine / Q000652:urine; D003430:Cross-Sectional Studies; D004032:Diet; D015930:Diet Records; D014676:Diet, Vegetarian; D004044:Dietary Proteins / Q000008:administration & dosage* / Q000652:urine*; D005260:Female; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008875:Middle Aged; D014556:Urine / Q000737:chemistry*; D055815:Young Adult
D000143:Acids; D004044:Dietary Proteins; D003404:Creatinine