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.
Design
This study used a cross-sectional design.
Setting and Participants
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.
∗Gerald J. and Dorothy R. Friedman School of Nutrition Science and Policy, Tufts University, Boston, Massachusetts
†Department of Public Health and Family Medicine, Tufts University School of Medicine, Boston, Massachusetts
§Jean Mayer United States Department of Agriculture Human Nutrition Research Center on Aging, Tufts University, Boston, Massachusetts
Address reprint requests to Lynne Ausman, DSc, RD, Gerald J. and Dorothy R. Friedman School of Nutrition Science and Policy, Tufts University, 150 Harrison Ave., Boston, MA 02111.
Disclaimer: This material is based on work supported by contract CB 74104 from the Breast Cancer Task Force of the National Cancer Institute and by the U.S. Department of Agriculture. Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the authors, and do not necessarily reflect the view of the U.S. Department of Agriculture.
ABSTRACT