Effect of Snacks on Aging

July 29, 2026 updated by: Zhaoping Li, University of California, Los Angeles

Effect of Pecan Consumption on Aging

The purpose of this study is to determine if daily consumption of 2 oz of pecans compared to 3.5 oz pretzel snacks for 12 weeks will 1) contribute to the body's ability to protect itself from oxidative damage (caused by oxygen radicals created by ultraviolet (UV) B light) by evaluating skin resistance to UV light irritation, skin fats/oils degradation and "rusting", and oxidative damage to the skin genes; and 2) explore the mechanisms of how snack consumption may affect aging by analyzing blood markers of aging as well as the microbes living in the gut (gut microbiome).

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Active, not recruiting

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

Detailed Description

Oxidative stress plays a significant role in the aging process. Antioxidant potential of tree nuts, including pecans, has been previously reported. However, very few studies have evaluated the antioxidant effects and their underlying mechanisms of nut consumption in the aging population. Skin is the largest organ and is the first body part to exhibit signs of aging. Human skin exposed to solar ultraviolet radiation (UVR) experiences a dramatic increase in production of reactive oxygen species (ROS) and inflammation. Moreover, skin aging is associated with increased levels of oxidative stress. Investigators previously showed that almond and pomegranate consumption can improve the antioxidant defense of skin by reducing UV-induced damage. In addition, the prebiotic properties of nuts and other bioactive-rich foods have been of great interest lately, current study team and others have reported the gut microbiome modulating effects of tree nut consumption. Based on this evidence and other published data, it is being proposed that pecans, due to their bioactive compound content, may have the potential to contribute to whole body antioxidant protection, modulate the gut microbiome and affect the aging process. The aim of this study is to evaluate the effects of incorporating 2 oz of pecans into diet compared to isocaloric pretzel snacks daily for 12 weeks 1) on whole body antioxidant capacity by evaluating skin resistance to UV irritation, lipid oxidation, and oxidative DNA damage; and 2) explore the mechanism of how pecan consumption affects aging by analyzing circulating biomarkers of aging as well as the gut microbiome. This will be a two-arm, randomized, placebo-controlled intervention study in 60 middle-aged and older generally healthy non-vegetarian/vegan women (age 55-75 years, Fitzpatrick's skin types II-IV). Investigating the effects of pecan consumption on skin antioxidant defense and systemic oxidative status will uncover valuable new insights into whether bioactive compounds in pecans can contribute to the total body antioxidant capacity and affect the aging process.

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Interventional

Enrollment (Estimated)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
60

Phase

Phase

The stage of a clinical trial studying a drug or biological product, based on definitions developed by the U.S. Food and Drug Administration (FDA). The phase is based on the study's objective, the number of participants, and other characteristics. There are five phases: Early Phase 1 (formerly listed as Phase 0), Phase 1, Phase 2, Phase 3, and Phase 4. Not Applicable is used to describe trials without FDA-defined phases, including trials of devices or behavioral interventions.
  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Contact

The name and contact information for the person who can answer enrollment questions for a clinical study. Each location where the study is being conducted may also have a specific contact, who may be better able to answer those questions.

Study Locations

  • United States
    • California
      • Los Angeles, California, United States, 90095
        • UCLA Center for Human Nutrition

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

Yes

Description

Inclusion Criteria:

  • Female
  • Generally healthy
  • Aged 55-75 years
  • BMI 18.5-34.9 kg/m2
  • Fitzpatrick Skin type II-IV
  • Consume a typical Western diet (low in polyphenols-rich foods and fiber)
  • Willing to maintain habitual dietary and exercise patterns for the study duration
  • Willing to maintain normal skin care products and pattern for the duration of the study
  • Willing to come to study visits without any makeup and skin products on
  • Subjects must read and sign the Institutional Review Board-approved written informed consent prior to the initiation of any study specific procedures or enrollment. A subject will be excluded for any condition that might compromise the ability to give truly informed consent.

Exclusion Criteria:

  • Vegetarian/vegan
  • Known nut allergy
  • Skin-related prescription medication, supplements or non-prescription cosmeceutical agents
  • Initiation of topical or oral prescription steroids and/or anti-inflammatory medications within 30 days prior to study enrollment
  • Excessive exposure to either natural or artificial sunlight
  • Screening laboratory values outside of the normal range that is considered clinically significant for study participation by the investigator
  • Documented chronic disease
  • Taking medications or supplements known to affect gut microbiota composition (antibiotics within the past 3 months, probiotics, fiber, etc.)
  • Taking exogenous hormones (e.g. hormone replacement therapy)
  • Recent weight fluctuations (>10% in the last 6 months)
  • Smoker or living with a smoker
  • Use of >20 g of alcohol per day
  • Unable or unwilling to comply with the study protocol (including unwillingness to avoid nuts for the whole duration of the study)
  • Unable to provide consent
  • Pregnancy and/or lactation

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Prevention
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: Double

Arms and Interventions

Participant Group / Arm

Participant Group / Arm

A group or subgroup of participants in a clinical trial that receives a specific intervention/treatment, or no intervention, according to the trial's protocol.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
Experimental: Pecan arm
Participats in this arm will be comsuming 2 oz of pecans daily for 12 wekks
Other: Pecan
2 oz of whole raw pecans
Experimental: Pretzel arm
Participants in this arm will consume 3.5 oz of pretzel snacks daily for 12 weeks
Other: Pretzel
3.5 oz of pretzel snacks daily

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Measure Description
Time Frame
Minimal Erythema Dose (MED)
Time Frame: At baseline and 12 weeks
To determine the minimal erythema dose (MED) at the inner arm, skin UVB dose and treatment time will be determined based on overall skin type classification. Based on overall skin type classification we will use the National Biological UVB mJ chart to determine the dose and sequential exposure times for each skin patch. A sleeve with 6 cutout patches will be placed on participant's arm. Using the Dermalight 90 handheld device (National Biological, Beachwood, OH) each cutout test area on the inner arm of subjects will be exposed to a defined dose of narrow band ultraviolet B (NB-UVB) light delivered by the UV exposure between 270 and 400 nm. Each cutout window will be exposed to an increasing dose. To evaluate the minimal erythema dose (MED) participants will need to return 24 hours later to determine which skin patch showed minimal erythema (pink color). Although 6 cutouts will be made, this is a single outcome measure as the all 6 cutouts will all be measuring MED in mJ/cm^2.
At baseline and 12 weeks

Secondary Outcome Measures

Secondary Outcome Measures

In a clinical study's protocol, a planned outcome measure that is not as important as the primary outcome measure for evaluating the effect of an intervention but is still of interest. Most clinical studies have more than one secondary outcome measure.
Outcome Measure
Measure Description
Time Frame
Skin characteristics
Time Frame: At baseline and 12 weeks
skin elasticity (Cutometer Dual MPA 580) in N/m
At baseline and 12 weeks
Skin characteristics
Time Frame: At baseline and 12 weeks
hydration (Corneometer CM 825) in AU
At baseline and 12 weeks
Skin characteristics
Time Frame: At baseline and 12 weeks
color (Mexameter MX18) in AU
At baseline and 12 weeks
Skin characteristics
Time Frame: At baseline and 12 weeks
skin gloss (SkinGlossymeter GL200) in GU
At baseline and 12 weeks

Other Outcome Measures

Other Outcome Measures

For clinical trials, a planned measurement described in the protocol that is used to determine the effect of an intervention/treatment on participants. For observational studies, a measurement or observation that is used to describe patterns of diseases or traits, or associations with exposures, risk factors, or treatment. Types of outcome measures include primary outcome measure and secondary outcome measure.
Outcome Measure
Measure Description
Time Frame
Biomarkers of aging and inflammation
Time Frame: At baseline and 12 weeks
C-C motif chemokine 27 (CTACK/CCL27) in pg/ml
At baseline and 12 weeks
Biomarkers of aging and inflammation
Time Frame: At baseline and 12 weeks
fibroblast growth factor 21 (FGF-21) in pg/ml
At baseline and 12 weeks
Biomarkers of aging and inflammation
Time Frame: At baseline and 12 weeks
growth/differentiation factor 11 (GDF-11) in ng/ml
At baseline and 12 weeks
Biomarkers of aging and inflammation
Time Frame: At baseline and 12 weeks
growth/differentiation factor 15 (GDF-15) in pg/ml
At baseline and 12 weeks
Biomarkers of aging and inflammation
Time Frame: At baseline and 12 weeks
gonadoliberin (GnRH) in pg/ml
At baseline and 12 weeks
Biomarkers of aging and inflammation
Time Frame: At baseline and 12 weeks
interleukin-6 (IL-6) in pg/ml
At baseline and 12 weeks
Biomarkers of aging and inflammation
Time Frame: At baseline and 12 weeks
interleukin-10 (IL-10) in pg/ml
At baseline and 12 weeks
Biomarkers of aging and inflammation
Time Frame: At baseline and 12 weeks
interleukin-18 (IL-18) in pg/ml
At baseline and 12 weeks
Biomarkers of aging and inflammation
Time Frame: At baseline and 12 weeks
Jagged 1 protein (Jag1) in kDA
At baseline and 12 weeks
Biomarkers of aging and inflammation
Time Frame: At baseline and 12 weeks
leptin in ng/ml
At baseline and 12 weeks
Oxidative stress markers
Time Frame: At baseline and 12 weeks
Urine malondialdehyde (MDA) in ng/ml
At baseline and 12 weeks
Oxidative stress markers
Time Frame: At baseline and 12 weeks
Blood MDA in nmol/ml
At baseline and 12 weeks
Oxidative stress markers
Time Frame: At baseline and 12 weeks
Urine 8OHdG in ng/mg creatinine
At baseline and 12 weeks
Oxidative stress markers
Time Frame: At baseline and 12 weeks
Blood 8OHdG in ng/ml
At baseline and 12 weeks
Gut microbiome
Time Frame: At baseline and 12 weeks
The stool specimen will be collected by the participants at home at baseline and week 12 utilizing our Stool Collection Kit as per instructions. Immediately after collection, the specimen will be frozen in a home freezer and delivered in an insulated container to the UCLA Center for Human Nutrition. At UCLA, the specimen will be stored at - 80 ºC. Fecal microbiological analyses. Approximately 1g of the stool will be weighed and dried in a vacuum drying oven (15 in Hg) at 80 ºC for 48 hours, then weighed again to establish the moisture content so that all counts can be corrected to dry weight. From another aliquot of remaining fecal samples, DNA will be extracted using bead beating with a commercial extraction system (DNeasy PowerSoil® DNA Isolation Kit, Qiagen, Valencia, CA). The quality of the DNA samples will be confirmed using a Nanodrop 1000 (Thermo Fisher Scientific, Wilmington, DE). Extracted DNA will be transferred to UCLA Microbiome Core facility for MiSeq sequencing.
At baseline and 12 weeks

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
University of California, Los Angeles

Collaborators

Collaborators

An organization other than the sponsor that provides support for a clinical study. This support may include activities related to funding, design, implementation, data analysis, or reporting.
American Pecan Promotion Board

Investigators

Investigators

A researcher involved in a clinical study. Related terms include site principal investigator, site sub-investigator, study chair, study director, and study principal investigator.
  • Principal Investigator: Zhaoping Li, MD, PhD, University of California, Los Angeles

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
May 19, 2025

Primary Completion (Actual)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
June 12, 2026

Study Completion (Estimated)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
December 31, 2026

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
February 11, 2025

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
March 13, 2025

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
March 17, 2025

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
July 31, 2026

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
July 29, 2026

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
July 1, 2026

More Information

Terms related to this study

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • IRB-25-0037

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

IPD Plan Description

Data analysis will be performed in-house.

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

product manufactured in and exported from the U.S.

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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