Comparison of estimated renal net acid excretion from dietary intake and body size with urine pH.

TitleComparison of estimated renal net acid excretion from dietary intake and body size with urine pH.
Publication TypeJournal Article
Year of Publication2003
AuthorsMichaud, DS, Troiano, RP, Subar, AF, Runswick, S, Bingham, S, Kipnis, V, Schatzkin, A
JournalJ Am Diet Assoc
Pagination1001-7; discussion 1007
Date Published2003 Aug
KeywordsAcids, Adult, Aged, Diet, Dietary Proteins, Energy Intake, Exercise, Female, Humans, Hydrogen-Ion Concentration, Kidney, Male, Mental Recall, Middle Aged, Statistics, Nonparametric, Surveys and Questionnaires, Urine

OBJECTIVE: The aim of this study was to examine whether estimated net acid excretion (NAE) from two dietary assessment instruments can predict urine pH in healthy volunteers.DESIGN: The Observing Protein and Energy Nutrition (OPEN) study, which was designed to assess dietary measurement error, included men and women aged 40 to 69 years. Participants were asked to complete two food frequency questionnaires (FFQs) and two 24-hour recalls at approximately three-month intervals, and to return two 24-hour urine samples during the same period. NAE was estimated using a previously described equation. The estimates obtained from the different dietary assessment measures were correlated with actual urine pH.SUBJECTS/SETTING: Four hundred eighty-four subjects were enrolled in the OPEN study. All participants were included in this study on urine pH, given that they had all completed at least one dietary assessment and one urine sample. The study took place in Montgomery County, MD, between September 1999 and March 2000.RESULTS: Correlation coefficients between NAE estimates using the FFQ data and the average of two urine pH measures were -0.34 and -0.39 for women and men, respectively. Removing within-person variance in the urine pH levels resulted in a deattenuated overall correlation of -0.50 for the FFQ. Correlations between the 24-hour recall estimates of NAE were -0.41 and -0.32 for women and men, respectively. For the 24-hour recalls, the deattenuated overall correlation was -0.50.APPLICATION/CONCLUSIONS: Our findings suggest that FFQs provide adequate dietary data to estimate renal NAE and could be used as a surrogate for urinary pH levels in large epidemiologic studies.

Alternate JournalJ Am Diet Assoc
Citation Key10.1016/s0002-8223(03)00469-3
PubMed ID12891148