Progression of chronic kidney disease (CKD) and cardiovascular disease risk in hypertensive adults was significantly slower among those who consumed more fruits and vegetables or oral sodium bicarbonate, compared with controls who received usual care.
A primary focus on pharmacologic strategies has failed to reduced hypertension-related CKD and cardiovascular disease mortality, Nimrit Goraya, MD, of Texas A&M Health Sciences Center College of Medicine, Temple, and colleagues wrote. High-acid diets (those with greater amounts of animal-sourced foods) have been associated with increased incidence and progression of CKD and with increased risk of cardiovascular disease.
Diets high in fruits and vegetables are associated with reduced CKD and cardiovascular disease but are not routinely used as part of hypertension treatment. The researchers hypothesized that dietary acid reduction could slow kidney disease progression and reduce cardiovascular disease risk.
In a study published in The American Journal of Medicine, the researchers randomized 153 adults aged 18-70 years with hypertension and CKD to fruits and vegetables, oral sodium bicarbonate (NaHCO3), or usual care; 51 to each group. The fruit and vegetable group received 2-4 cups daily of base-producing food items including apples, apricots, oranges, peaches, pears, raisins, strawberries, carrots, cauliflower, eggplant, lettuce, potatoes, spinach, tomatoes, and zucchini. Participants were not instructed how to incorporate these foods into their diets. The sodium bicarbonate group received an average of four to five NaHCO3 tablets daily (650 mg), divided into two doses.
The mean age of the participants was 48.8 years, 51% were female, and 47% were African American. The primary outcome was CKD progression and cardiovascular disease risk over 5 years. All participants met criteria at baseline for macroalbuminuria (a urine albumin to creatinine ratio of at least 200 mg/g) and were considered at increased risk for CKD progression.
Over the 5-year follow-up, CKD progression was significantly slower in the groups receiving fruits and vegetables and oral sodium bicarbonate, compared with usual care, based on trajectories showing a lower decline of estimated glomerular filtration rates (mean declines of 1.08 and 1.17 for fruits/vegetables and NaHCO3, respectively, vs 19.4 for usual care, P < .001 for both).
However, systolic blood pressure and subsequent cardiovascular disease risk indicators were lower only in the fruit and vegetable group, compared with both the NaHCO3 or usual-care groups over the long term. “Specifically, with fruits and vegetables, systolic blood pressure, plasma LDL and Lp(a) cholesterol, and body mass index decreased from baseline, consistent with better cardiovascular disease protection,” the researchers wrote. The protection against cardiovascular disease in the fruits and vegetables group occurred with lower doses of antihypertensive and statin medications and was not affected by baseline differences in medication doses.
The findings were limited by several factors, including the lack of data on compliance with the NaHCO3 supplements, although urine net acid excretion in this group suggested increased alkali intake similar to that provided by fruits and vegetables, the researchers noted. Other limitations included the focus only on individuals with very high albuminuria.
More basic science studies are needed to explore how the potential vascular injury suggested by albuminuria affects CKD progression and cardiovascular disease, and clinical studies are needed to assess the impact of dietary acid reduction on patients with lower levels of albuminuria that the current study, the researchers said.
However, the results suggest that consuming fruits and vegetables, rather than NaHCO3, is the preferred strategy for dietary acid reduction for patients with primary hypertension and CKD, they concluded. The findings also support routine measurement of urine albumin-to-creatinine ratios in hypertensive patients to identify CKD and assess risk for progression and subsequent cardiovascular disease.
The study was supported by the Larry and Jane Woirhaye Memorial Endowment in Renal Research at the Texas Tech University Health Sciences Center, the University Medical Center (both in Lubbock, Texas), the Endowment, Academic Operations Division of Baylor Scott & White Health, and the Episcopal Health Foundation. The researchers had no financial conflicts to disclose.