Walnuts for Cardiorenal Protection in Adults With Chronic Kidney Disease

NCT07851454 | Recruiting

• 1 other identifier: PI25/01680
• Study Type: interventional
• Target: 150
• Locations: 1 country
• Sites: 1

Brief 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. 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. 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

Conditions

CKD - Chronic Kidney Disease; Renal Function; Cardiovascular Biomarkers

Keywords

Nuts; Walnut; Mediterranean diet; Kidney function; Chronic kidney disease; Inflammation; Intestinal dysbiosis

Outcome Measures

Primary Outcomes (3)

• Change from baseline in renal function

  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.

  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.

• Chronic Kidney Disease (CKD) Progression

  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.

  CKD progression will be evaluated at the end of the 6-month follow-up period.

• Chronic Kidney Disease (CKD) remission

  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.

  CKD remission will be evaluated at the end of the 6-month follow-up period.

Secondary Outcomes (24)

• Change from baseline in urinary albumin-to-creatinine ratio (UACR)

  Participants will be followed for 6 months. Measurements will be done at baseline, at the 3-month follow-up period, and at the end of the 6-month follow-up period

• Change from baseline in mineral and bone metabolism markers

  Participants will be followed for 6 months. Measurements will be done at baseline, at the 3-month follow-up period, and at the end of the 6-month follow-up period.

• Change from baseline in body weight

  Participants will be followed for 6 months. Measurements will be done at baseline, at the 3-month follow-up period, and at the end of the 6-month follow-up period.

• Change from baseline in waist circumference

  Participants will be followed for 6 months. Measurements will be done at baseline, at the 3-month follow-up period, and at the end of the 6-month follow-up period.

• Change from baseline in Body Mass Index (BMI)

  Participants will be followed for 6 months. Measurements will be done at baseline, at the 3-month follow-up period, and at the end of the 6-month follow-up period.

Study Arms (2)

Daily Walnut Consumption

EXPERIMENTAL

Participants in the intervention group will consume 30 g/day of raw walnuts in addition to receiving a Mediterranean diet (MedDiet)-based dietary counseling program. To ensure and facilitate adherence, participants will receive two educational leaflets: one providing practical guidance on following a MedDiet and another containing MedDiet-compatible recipes incorporating walnuts. They will also receive written guidance on optimizing phosphorus and potassium intake within a Mediterranean dietary pattern, including information on food sources, hidden additives, and cooking techniques that may reduce mineral content. Walnuts will be provided free of charge and distributed at baseline and at each follow-up visit.

Other: Daily Walnut Consumption

Control: MedDiet-based dietary counseling

NO INTERVENTION

Participants in the control group will receive the same MedDiet-based dietary counseling without walnut supplementation.

Interventions

Daily Walnut Consumption OTHER

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.

Daily Walnut Consumption

Eligibility Criteria

• Age: 45 Years - 75 Years
• Sex: all
• Healthy Volunteers: No
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

• Men and women with stable mild to moderate chronic kidney disease \[CKD\] (stage G3a-b (estimated glomerular filtration rate \[eGFR\] 30-\<60mL/min/1.73 m²) and albuminuria stages A1-3 (UACR from \< 30mg/g to ≥ 300 mg/g))
• years old at screening
• Overweight/obesity (Body Mass Index \[BMI\] ≥25 and ≤40 kg/m²)
• Meet at least one of the following conditions:
• (i) Systolic blood pressure ≥140 mmHg or diastolic blood pressure ≥90 mmHg, or use of antihypertensive agents (ii) Triglycerides ≥150 mg/dL, LDL cholesterol ≥160 mg/dL, HDL cholesterol ≤40 mg/dL in men or ≤50 mg/dL in women, or use of lipid-modifying medication (iii) Prediabetes or type 2 diabetes according to the American Diabetes Association (ADA) Standards, or use of glucose-lowering medication.

You may not qualify if:

• Inability to give written informed consent
• CKD caused by polycystic kidney disease, chronic pyelonephritis, and renal dysplasia
• CKD on renal replacement therapy (hemodialysis, peritoneal dialysis, and kidney transplant recipients)
• Acute exacerbation of CKD, whether due to extrarenal causes (decompensated heart failure, infectious disease or sepsis, surgical intervention) or due to an outbreak of underlying glomerular or systemic renal pathology, with changes in treatment in the last 2 months.
• Nut allergy
• Alcoholism (\>50 g/day) or drug abuse
• Treatment with immunosuppressant drugs or cytotoxic agents
• Any other medical condition that interferes with the completion of the protocol (pregnancy/breastfeeding, history of inflammatory bowel disease, liver failure, cancer or active neoplasms, psychiatric problems)
• Institutionalization of the participant.

Sponsors & Collaborators

• Institut Investigacio Sanitaria Pere Virgili: lead

Study Sites (1)

Unit for Public Health and Nutritional Epidemiology, Faculty of Medicine and Health Sciences, Universitat Rovira i Virgili

Reus, Tarragona, 43201, Spain

RECRUITING

MeSH Terms

Conditions

Renal Insufficiency, Chronic; Inflammation

Condition Hierarchy (Ancestors)

Renal Insufficiency; Kidney Diseases; Urologic Diseases; Female Urogenital Diseases; Female Urogenital Diseases and Pregnancy Complications; Urogenital Diseases; Male Urogenital Diseases; Chronic Disease; Disease Attributes; Pathologic Processes; Pathological Conditions, Signs and Symptoms

Central Study Contacts

Andrés Díaz López, PhD

CONTACT

+34 977759372; andres.diaz@urv.cat

Verónica Ruíz García, PhD

CONTACT

+34 677150430; vruiz.hj23.ics@gencat.cat

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: NONE
• Purpose: TREATMENT
• Intervention Model: PARALLEL
• Sponsor Type: OTHER
• Responsible Party: SPONSOR

Study Record Dates

• First Submitted: August 27, 2026
• First Posted: October 1, 2026
• Study Start: August 4, 2026
• Primary Completion (Estimated): February 1, 2028
• Study Completion (Estimated): June 1, 2028
• Last Updated: October 1, 2026

Record last verified: 2026-09

Locations

ES (1)