Response of Cardiometabolic Biomarkers and Gut Microbiota to Walnut Consumption

NCT05321277 | Active Not Recruiting

• 1 other identifier: 1867437
• Study Type: interventional
• Target: 30
• Locations: 1 country
• Sites: 1

Brief Summary

The purpose of this research is to test if eating walnuts will cause any changes in blood lipids (like good and bad cholesterol, for example) and levels of inflammation in the blood, as well as changes in the bacteria living in the gut.

Conditions

Cardiovascular Diseases

Keywords

heart health; gut microbiota; Mediterranean diet; cardiometabolic health; gut health; diet

Outcome Measures

Primary Outcomes (3)

• Assessing the influence of walnut consumption on blood lipid measurements.

  Measure for changes in the levels of HDL and LDL in separated plasma; measured in units of mg/dL. Blood will be assessed for the fasting (baseline) sample at each of the 4 study visits.

  Through study completion, an average of 10 weeks

• Assessing the influence of walnut consumption on circulating inflammatory markers: PAI-1, VCAM-1 and ICAM-1.

  Measure circulating inflammatory markers in separated plasma at each of the 4 study visits. Commercially available ELISA kits will be used: PAI-1, VCAM-1, ICAM-1.

  Through study completion, an average of 10 weeks

• Assessing the influence of walnut consumption on blood pressure.

  Measure blood pressure (mmHg) before the start of drawing blood on study day protocols.

  Through study completion, an average of 10 weeks

Secondary Outcomes (5)

• Assessing the influence of walnut consumption on fecal pH.

  Through study completion, an average of 10 weeks

• Assessing the influence of walnut consumption on stool consistency.

  Through study completion, an average of 10 weeks

• Assessing the influence of walnut consumption on fecal moisture.

  Through study completion, an average of 10 weeks

• Assessing the influence of walnut consumption on the levels of gut inflammatory markers: Lipocalin-2 and calprotectin.

  Through study completion, an average of 10 weeks

• Assessing the influence of walnut consumption on plasma and urine levels of walnut-derived metabolites - urolithins.

  Through study completion, an average of 10 weeks

Other Outcomes (3)

• Food record analysis

  Through study completion, an average of 10 weeks

• Anthropometric measurements

  Through study completion, an average of 10 weeks

• Measure of changes in weight

  Through study completion, an average of 10 weeks

Study Arms (2)

Walnut diet

ACTIVE COMPARATOR

Participants will consume 56 g of walnuts each day at home for 3 weeks.

Dietary Supplement: Walnuts

No-nut diet

ACTIVE COMPARATOR

Participants will follow a no-nut diet for 3 weeks.

Dietary Supplement: No-nut diet

Interventions

Walnuts DIETARY_SUPPLEMENT

Participants will consume 56 g of walnuts daily for 3 weeks. Participants will also follow a diet devoid of ellagitannin-rich, high fiber, and fermented foods.

Walnut diet

No-nut diet DIETARY_SUPPLEMENT

Participants will exclude all nuts and nut-derived products; high-fiber, fermented and ellagitannin-rich foods will also be excluded.

No-nut diet

Eligibility Criteria

• Age: 45 Years - 70 Years
• Sex: all
• Healthy Volunteers: No
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

• Overweight and obese men and postmenopausal women between 45-70 years of age, BMI range of 25.0-39.9 kg/m2 and elevated LDL-C levels (130-189 mg/dL).

You may not qualify if:

• Adults unable to consent, individuals who are not yet adults (infants, children, teenagers), pregnant or lactating women, women planning to become pregnant in the next four months and prisoners will be specifically excluded.
• Allergy to walnuts or other nuts
• Eating more than 25 grams of fiber per day, assessed by the Block Dietary-Fruit-Vegetable-Fiber Screener©
• Taking medications or supplements known to affect metabolism or gut microbiota composition (i.e. Metformin, statins, antibiotics within the past 3 months, fiber supplements, probiotics, and others)
• Documented chronic diseases including diabetes, renal or liver disease, metabolic syndrome, active cancer, MI or stroke, history of gastric bypass or GI disease (e.g. Crohn's Disease, Irritable Bowel Disease, diverticulosis, diverticulitis, etc.)
• Smoker or living with a smoker, including vaporizer and/or electronic cigarettes.
• Illicit drug use, cannabis usage, or consuming \>1 alcoholic drink/day
• Extreme dietary or exercise patterns
• Recent weight fluctuations (\>10% in the last 6 months)
• Taking prescription lipid medications or supplements that may affect lipoprotein metabolism (i.e. \>1 g of fish oil/day, antioxidant supplements)
• Taking exogenous hormones
• Poor venous access
• Unwillingness to comply with study protocols

Sponsors & Collaborators

• University of California, Davis: lead

Study Sites (1)

Ragle Human Nutrition Center

Davis, California, 95616, United States

Location

MeSH Terms

Conditions

Cardiovascular Diseases

Study Design

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

Study Record Dates

• First Submitted: April 1, 2022
• First Posted: April 11, 2022
• Study Start: April 19, 2022
• Primary Completion: June 11, 2024
• Study Completion (Estimated): August 1, 2026
• Last Updated: February 10, 2026

Record last verified: 2026-02

Data Sharing

• IPD Sharing: Will not share

Locations

US (1)