Dietary acid, age, and serum bicarbonate levels among adults in the United States.
OBJECTIVE
Greater dietary acid has been associated with lower serum bicarbonate levels in patients with CKD. Whether this association extends to the general population and if it is modified by age are unknown.


METHODS
This study examined the association of the dietary acid load, estimated by net endogenous acid production, with serum bicarbonate levels in adult participants in the National Health and Nutrition Examination Survey 1999-2004.


RESULTS
The mean serum bicarbonate was 24.9 mEq/L (SEM=0.1), and the mean estimated net endogenous acid production was 57.4 mEq/d (SEM=0.4). Serum bicarbonate was linearly associated with age, such that the oldest participants had the highest serum bicarbonate levels. After multivariable adjustment, participants in the highest quartile of net endogenous acid production had 0.40 mEq/L (95% confidence interval, -0.55 to -0.26) lower serum bicarbonate and a 33% (95% confidence interval, 3 to 72) higher likelihood of acidosis compared with those participants in the lowest quartile. There was a significant interaction by age of the association of net endogenous acid production with serum bicarbonate (P=0.005). Among participants 20-39, 40-59, and ≥60 years old, those participants in the highest net endogenous acid production quartile had 0.26 (95% confidence interval, -0.49 to -0.03), 0.60 (95% confidence interval, -0.92 to -0.29), and 0.49 (95% confidence interval, -0.84 to -0.14) mEq/L lower serum bicarbonate, respectively, compared with participants in the lowest quartile.


CONCLUSIONS
Greater dietary acid is associated with lower serum bicarbonate in the general US population, and the magnitude of this association is greater among middle-aged and elderly persons than younger adults.
Division of Nephrology, Department of Medicine and, †Department of Epidemiology and Population Health, Albert Einstein College of Medicine, Bronx, New York.
Afolarin
A
Amodu
Matthew K
MK
Abramowitz
D000136:Acid-Base Equilibrium; D000138:Acidosis / Q000097:blood / Q000175:diagnosis / Q000453:epidemiology*; D000143:Acids / Q000009:adverse effects* / Q000378:metabolism; D000328:Adult; D000367:Age Factors; D001639:Bicarbonates / Q000097:blood*; D004032:Diet / Q000009:adverse effects*; D005260:Female; D006801:Humans; D006863:Hydrogen-Ion Concentration; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D009749:Nutrition Surveys; D016017:Odds Ratio; D015995:Prevalence; D012307:Risk Factors; D014481:United States / Q000453:epidemiology; D055815:Young Adult
D000143:Acids; D001639:Bicarbonates