Walnuts for Cardiorenal Protection in Adults With Chronic Kidney Disease

Condition(s) studied

Investigational drug(s) / intervention(s)

Daily Walnut Consumption: Participants in the intervention group will consume 30 g/day of raw walnuts for 6 months in addition to receiving a Mediterranean diet (MedDiet)-based dietary counseling program.

Study summary

To date, no rigorous randomized controlled trials have demonstrated a protective effect of daily moderate walnut consumption on kidney function or chronic kidney disease (CKD) progression in individuals with CKD.

Objective: To determine the effect of walnut supplementation (30 g/day of raw walnuts) within a Mediterranean diet (MedDiet) based dietary counseling program, compared with the same MedDiet counseling program without walnut supplementation, on kidney function, CKD progression and regression, and classical and emerging cardiovascular risk markers in individuals with CKD. Secondary objectives focus on assessing whether regular walnut consumption as a healthy snack has a positive impact on inflammation, oxidative stress, endothelial dysfunction, and intestinal dysbiosis, conditions intrinsically linked to CKD that play a pathophysiological role in promoting/exacerbating its progression and the development of comorbidities in this vulnerable group of subjects.

Methodology: A 6-month randomized controlled trial will be conducted in 150 men and women aged 45 to 75 years with stable mild to moderate CKD (stage G3a-b), overweight or obesity, and high cardiometabolic risk. The study will compare the effect of two interventions assessed at 3 and 6 months on the following outcomes:

1. Primary outcomes: a) changes in kidney function assessed by the Estimated Glomerular Filtration Rate based on creatinine and cystatin C (eGFRcr-cys); b) CKD progression; and c) CKD remission
2. Secondary outcomes: a) urinary albumin-to-creatinine ratio (UACR); b) mineral and bone metabolism parameters, c) anthropometry and body composition (Dual-Energy X-ray Absorptiometry, DXA); d) bone mineral density (DXA); e) diet quality; f) physical activity; g) medication use; h) psychological well-being; i) quality of life; j) classic cardiovascular risk markers; k) iron status and hepatic function; l) inflammation, endothelial function, and oxidation markers; m) gut microbiota

Eligibility

Primary outcome measure(s)

• Change from baseline in renal function — Participants will be followed for 6 months, with renal function assessments conducted at baseline, at the 3-month follow up period, and at the end of the 6-month follow-up period.
  Renal function will be estimated using the estimated glomerular filtration rate (eGFR) calculated from serum creatinine (eGFRcr), cystatin-C (eGFRcys), or both (eGFRcr-cys), applying the CKD-Epidemiology Collaboration 2021 equation. Serum creatinine and cystatin C concentrations will be obtained from routine biochemical analyses performed as part of the participants' standard clinical care at the hospital.
• Chronic Kidney Disease (CKD) Progression — CKD progression will be evaluated at the end of the 6-month follow-up period.
  CKD progression will be assessed using eGFRcr-cys and defined as the first occurrence, during the 6-month intervention period, of any of the following criteria: (i) a decline in eGFRcr-cys of \>2.5 mL/min/1.73 m² from baseline; (ii) a relative decline in eGFRcr-cys of \>10% from baseline; or (iii) progression to a more advanced stage of kidney function impairment, defined as a transition from G3a to G3b or from G3b to G4 or higher.
• Chronic Kidney Disease (CKD) remission — CKD remission will be evaluated at the end of the 6-month follow-up period.
  CKD remission will be assessed using eGFRcr-cys and defined as the first occurrence, during the 6-month intervention period, of any of the following criteria: (i) an increase in eGFRcr-cys of \>2.5 mL/min/1.73 m² from baseline; or (ii) improvement to a less advanced stage of kidney function impairment, defined as a transition from G3b to G3a or from G3a to G2 or lower.

Trial sites (1)

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