A Comparison of Treating Metabolic Acidosis in CKD Stage 4 Hypertensive Kidney Disease with Fruits and Vegetables or Sodium Bicarbonate

Abstract

SummaryBackground and objectives Current guidelines recommend Na + -based alkali for CKD with metabolic acidosis and plasma total CO 2 (PTCO 2 ) , 22 mM. Because diets in industrialized societies are typically acid-producing, we compared base-producing fruits and vegetables with oral NaHCO 3 (HCO 3 ) regarding the primary outcome of follow-up estimated GFR (eGFR) and secondary outcomes of improved metabolic acidosis and reduced urine indices of kidney injury.Design, setting, participants, & measurements Individuals with stage 4 (eGFR, 15-29 ml/min per 1.73 m 2 ) CKD due to hypertensive nephropathy, had a PTCO 2 level , 22 mM, and were receiving angiotensin-converting enzyme inhibition were randomly assigned to 1 year of daily oral NaHCO 3 at 1.0 mEq/kg per day (n=35) or fruits and vegetables dosed to reduce dietary acid by half (n=36).Results Plasma cystatin C-calculated eGFR did not differ at baseline and 1 year between groups. One-year PTCO 2 was higher than baseline in the HCO 3 group (21.261.3 versus 19.561.5 mM; P,0.01) and the fruits and vegetables group (19.961.7 versus 19.361.9 mM; P,0.01), consistent with improved metabolic acidosis, and was higher in the HCO 3 than the fruits and vegetable group (P,0.001). One-year urine indices of kidney injury were lower than baseline in both groups. Plasma [K + ] did not increase in either group.Conclusions One year of fruits and vegetables or NaHCO 3 in individuals with stage 4 CKD yielded eGFR that was not different, was associated with higher-than-baseline PTCO 2 , and was associated with lower-than-baseline urine indices of kidney injury. The data indicate that fruits and vegetables improve metabolic acidosis and reduce kidney injury in stage 4 CKD without producing hyperkalemia.

The Association between a Mediterranean-Style Diet and Kidney Function in the Northern Manhattan Study Cohort

“…Similar findings have been reported elsewhere, with improvement in metabolic acidosis and phosphorus metabolism as possible mechanisms of action (41)(42)(43).…”

“…This could conceivably be extended to a CKD population, where numerous dietary trials involving protein restriction have been performed. Moreover, recent randomized trials involving high fruit and vegetable intake have shown safety and potential benefit in even advanced CKD, increasing the feasibility of a Mediterranean diet trial in this population (41,42). Strengths of this study include the duration of followup, a well characterized cohort, a valid food frequency questionnaire, adjustment for multiple confounders, and multiethnic composition that permits generalizability of results.…”

Dietary Acid, Age, and Serum Bicarbonate Levels among Adults in the United States

“…Even among individuals without kidney disease, a lowgrade acidosis contributes to bone breakdown and possibly loss of muscle mass (9,10), and low-normal serum bicarbonate levels have been associated with lesser muscle strength and cardiovascular fitness, greater insulin resistance, and faster progression of kidney disease (6,7,13,26). Interventions to treat acidosis, including dietary modifications (27,28), may be most efficacious among older persons, in whom the capacity to excrete the daily acid load from modern Western diets is diminished. We also observed an unexpected association between serum bicarbonate and age.…”

Mediterranean Diet, Kidney Function, and Mortality in Men with CKD

“…Strong evidence exists on the beneficial effects of a Mediterranean diet for incidence of several chronic diseases and reduced risk of mortality (7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19). Mechanisms underlying these relationships include benefits of this dietary pattern on the cardiometabolic profile (e.g., adiposity, BP, blood lipids, serum fasting glucose, insulin resistance, and inflammation [20,21]) as well as on metabolic acidosis (22,23). Because such risk factors are highly prevalent in CKD and contribute to its onset, it is plausible to hypothesize that adoption of this healthy dietary lifestyle may link to better preserved renal function.…”