A population health dietary intervention for African American adults with chronic kidney disease: The Fruit and Veggies for Kidney Health randomized study

The Fruit and Veggies for Kidney Health Study: A Prospective Randomized Trial

Rationale & Objective

Providing fruits and vegetables (F&Vs) to health care system patients with elevated urine albumin-creatinine ratio (ACR) reduced ACR, slowed chronic kidney disease (CKD) progression and reduced cardiovascular disease (CVD) risk factors in previous studies. This study evaluated a community-based strategy in lower-income populations to identify African Americans with elevated ACR before health care system involvement and sustain them in a 6-month F&V protocol with (F&V + Cook) and without (F&V Only) cooking instructions, with the hypothesis that adjuvant cooking instructions with F&Vs would further reduce ACR.

Study Design

Prospective, randomized, parallel 2-arm design.

Setting & Participants

African American adults with ACR >10 mg/g creatinine randomized to 1 of 2 study arms.

Interventions

Two cups/day of F&Vs with or without cooking instructions in participants followed 6 months.

Outcomes

Participants sustaining the F&V protocol and between-group indicators of CVD risk, kidney injury, and dietary intake at 6 weeks and 6 months.

Results

A total of 142 African American adults (mean age, 57.0 years; ACR, 27.4 mg/g; body mass index, 34.4; 24.9% CKD 1; 24.8% CKD 2; 50.4% CKD 3; 55% female) randomized to F&V Only (n=72) or F&V + Cook (n=70), and 71% were retained at 6 months. Participants received 90% of available F&V pick-ups over 6 weeks and 69% over 6 months. In the adjusted model, 6-month ACR was 31% lower for F&V + Cook than F&V Only (P = 0.02). Net 6-week F&V intake significantly increased and biometric variables improved for participants combined into a single group.

Limitations

Small sample size, low-baseline ACR, and potential nonresponse bias for 24-hour dietary recall measure.

Conclusions

These data support the feasibility of identifying community-dwelling African Americans with ACR indicating elevated CVD and CKD risk and sustaining a F&V protocol shown to improve kidney outcomes and CVD risk factors and provides preliminary evidence that cooking instructions adjuvant to F&Vs are needed to lower ACR.

Funding

National Institute on Diabetes, Digestive, and Kidney Diseases grant "Reducing chronic kidney disease burden in an underserved population" (R21DK113440).

Trial Registration

NCT03832166.

Plain-Language Summary

African Americans, particularly those in low-income communities, have increased rates of chronic kidney disease (CKD) with worsening outcomes over time. Giving fruits and vegetables to individuals with CKD identified in health care systems was previously shown to reduce kidney damage, measured by urine protein albumin, and slow kidney function decline. We recruited African Americans in low-income communities with increased urine albumin levels. They received fruits and vegetables for 6 months, and we tested whether added cooking instructions further reduced urine albumin levels. Most participants continued to receive fruits and vegetables throughout the 6 months. Those given cooking instructions had lower urine albumin levels after 6 months, indicating decreased kidney damage. Providing cooking instructions with fruits and vegetables appears to lessen kidney damage more than just fruits and vegetables alone.

Delay Early CKD with Lifestyle Intervention in African Americans with Diabetic Kidney Disease (DELAY DKD): A Pre-Post Pilot Study (Preprint)

Background

Behavioral factors, such as lifestyle, have been shown to explain approximately 24% of the excess risk of chronic kidney disease (CKD) among African Americans. However, there are limited intervention studies culturally tailored to African Americans with type 2 diabetes mellitus and CKD.

Objective

The main objective of this study was to examine the feasibility and preliminary efficacy of a culturally tailored lifestyle intervention among African Americans with type 2 diabetes mellitus and CKD.

Methods

A pre-post design was used to test the feasibility of a lifestyle intervention in 30 African American adults recruited from the Medical University of South Carolina between January 2017 and February 2017. A research nurse delivered the manualized study intervention weekly for 6 weeks. Clinical outcomes (hemoglobin A_1c, blood pressure, and estimated glomerular filtration rate [eGFR]) were measured at baseline and postintervention. Disease knowledge, self-care, and behavior outcomes were also measured using validated structured questionnaires at baseline and postintervention. Descriptive statistics and effect sizes were calculated to determine clinically important changes from baseline.

Results

Significant pre-post mean differences and decreases were observed for hemoglobin A_1c (mean 0.75%, 95% CI 0.16-1.34; P=.01), total cholesterol (mean 16.38 mg/dL, 95% CI 5.82-26.94; P=.004), low-density lipoprotein (mean 13.73 mg/dL, 95% CI 3.91-23.54; P=.008), and eGFR (mean 6.73 mL/min/1.73m², 95% CI 0.97-12.48; P=.02). Significant pre-post mean differences and increases were observed for CKD self-efficacy (mean −11.15, 95% CI −21.55 to −0.75; P=.03), CKD knowledge (mean −2.62, 95% CI −3.98 to −1.25; P<.001), exercise behavior (mean −1.21, 95% CI −1.96 to −0.46; P=.003), and blood sugar testing (mean −2.15, 95% CI −3.47 to −0.83; P=.003).

Conclusions

This study provides preliminary data for a large-scale appropriately powered randomized controlled trial to examine a culturally tailored lifestyle intervention in African Americans with type 2 diabetes mellitus and CKD in order to improve clinical, knowledge, self-care, and behavior outcomes in this population.

The Continuum of Acid Stress

Acid-related injury from chronic metabolic acidosis is recognized through growing evidence of its deleterious effects, including kidney and other organ injury. Progressive acid accumulation precedes the signature manifestation of chronic metabolic acidosis, decreased plasma bicarbonate concentration. Acid accumulation that is not enough to manifest as metabolic acidosis, known as eubicarbonatemic acidosis, also appears to cause kidney injury, with exacerbated progression of CKD. Chronic engagement of mechanisms to mitigate the acid challenge from Western-type diets also appears to cause kidney injury. Rather than considering chronic metabolic acidosis as the only acid-related condition requiring intervention to reduce kidney injury, this review supports consideration of acid-related injury as a continuum. This "acid stress" continuum has chronic metabolic acidosis at its most extreme end, and high-acid-producing diets at its less extreme, yet detrimental, end.