Objective

Diets high in sulfur-rich protein and low in fruit and vegetables affect human acid-base balance adversely and may have a harmful effect on progression of chronic kidney disease (CKD). Little is known about the relationship of participant characteristics, dietary acid load (DAL), and kidney injury in African-Americans with high risk of CKD progression.

Design and methods

We examined the association of DAL with CKD in 3,257 African-Americans aged >20 years in Jackson Heart Study. DAL was measured with nutrient intakes assessed with a food frequency questionnaire, using a model described by Remer and Manz. We tested associations of participant characteristics with DAL using median regression, and associations of DAL with albuminuria (>17 mg/g for men, >25 mg/g for women), reduced kidney function (eGFR <60 mL/minute/1.73 m 2), or CKD defined as albuminuria or reduced kidney function using logistic regression. We further explored whether endothelin and aldosterone production in participants with hypertension mediated risk of albuminuria or reduced kidney function due to the intake of an acid-inducing diet.

Results

Younger adults, men, and those with higher body mass index had higher DAL. Higher DAL, compared with lower, was associated with greater odds of reduced kidney function (OR [95% CI]: 2.82 [1.40-4.75]). Higher DAL was also associated with greater risk of CKD, and this persisted after adjustment for confounders. Results were similar in adults with hypertension; the OR [95% CI] for highest, versus lowest, tertile of DAL with albuminuria was 1.66 [1.01-2.59]. Aldosterone and endothelin mediated the association between DAL and albuminuria; the OR [95% CI] in the highest tertile was no longer significant 1.53 [0.97-2.40] after their inclusion.

Conclusions

Higher DAL was associated with higher prevalence of CKD and with reduced kidney function. DAL may be an important target for future interventions in African-Americans at high risk of CKD.