Diets Enriched With Pecans

Comparison of Health Effects of Diets With and Without Pecans

Background: Previous studies report that daily pecan consumption reduces cholesterol in healthy adults while promoting weight maintenance.

Purpose: To examine the impact of daily pecan consumption with and without dietary substitution instructions for an 8-week period on markers of health in adults at risk for cardiovascular disease.

Study Overview

• Status: Completed
• Conditions: Obesity; Hypercholesterolemia
• Intervention / Treatment: Dietary supplement: Pecan ADD; Dietary supplement: Pecan SUB

Detailed Description

This was a single-blind, randomized controlled trial. The investigators recruited subjects with hypercholesterolemia (high blood cholesterol levels) or at higher risk for cardiovascular disease (CVD) (BMI > 28 kg/m2). Subjects were randomized into one of three groups: (1) the no nut group (CON), (2) pecan ADD (no diet instructions), and (3) pecan SUB (instructions to substitute pecans with isocaloric foods in habitual diet).

There was a screening visit and 3 testing visits: Baseline (visit 1), mid-visit at week 4 (visit 2), and post-visit at week 8 (visit 3). Anthropometrics, questionnaires, and a fasting blood sample were collected at each visit. A subset of participants participated in a saturated fatty acid meal challenge in which additional blood and metabolism measurements were collected.

Hypothesis: The investigators hypothesized that daily pecan consumption would result in significantly greater improvements in blood lipids, metabolism, and appetite compared to the control group. The investigators also hypothesized that pecan ADD group will result in a larger increase in body weight compared to the pecan SUB and control groups.

• Study Type: Interventional
• Enrollment (Actual): 124
• Phase: Not Applicable

Contacts and Locations

Study Locations

• United States
  • Georgia
    • Athens, Georgia, United States, 30605
      • University of Georgia- Department of Foods and Nutrition

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 30 years to 75 years (ADULT, OLDER_ADULT)
• Accepts Healthy Volunteers: Yes
• Genders Eligible for Study: All

Description

Inclusion Criteria:

• Ages 30-75y with higher cholesterol levels or BMI of 28 kg/m2 or greater (A higher cholesterol level is indicated by "Borderline High/Undesirable" in two or more of the variables (total cholesterol 200-239 mg/dL, LDL cholesterol 130-159 mg/dL, triglycerides 150-199 mg/dL) or "High" in either total cholesterol (240 mg/dL and higher) or LDL (160 mg/dL or higher).

Exclusion Criteria:

• Familial hypercholesterolemia (individuals with LDL levels greater than the 95th percentile or HDL levels lower than the 20th percentile based on age and sex)
• Nut consumption >2 servings/week or tree nut butter consumption >3 servings/week
• Hormone replacement therapy <5 years
• Women who are pregnant or planning to become pregnant
• Regular exercise of >3 hours/week
• Weight gain or loss of >5% of body weight during last 3 months
• Plans to begin a weight loss/exercise regiment
• History of medical or surgical events that could affect digestion or swallowing
• Gastrointestinal surgeries, conditions or disorders
• Chronic or metabolic diseases
• Atherosclerosis, previous myocardial infarction, stroke, cancer
• Fasting blood glucose levels >126 mg/dl
• Blood pressure >180/120 mmHg
• Medication use that affects digestion, absorption, metabolism
• Lipid-lowering medications
• Medications for diabetes or attention deficit disorders (with or without hyperactivity)
• Steroid/hormone therapies
• Individuals on medically prescribed or special diet
• Individuals with food allergies to foods specifically in the study
• Individuals taking fish oil supplements
• Excessive alcohol consumption (greater than 3 drinks/d for men; greater than 2 drinks/d for women)
• Tobacco or nicotine use

Study Plan

How is the study designed?

Design Details

• Primary Purpose: OTHER
• Allocation: RANDOMIZED
• Interventional Model: PARALLEL
• Masking: SINGLE

Number of Arms

3

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
NO_INTERVENTION: Control; Participants in this group avoid all nuts for 8 weeks.
EXPERIMENTAL: Pecan ADD; Participants in this group consume 68 g of pecans/d with no additional dietary instructions and avoid all other nuts.	Dietary supplement: Pecan ADD; Raw pecan halves without dietary substitution instructions; Other Names: Pecan
EXPERIMENTAL: Pecan SUB; Participants in this group consume 68 g of pecans/d with instructions to substitute pecans with isocaloric foods in the habitual diet. They are also instructed to avoid all other nuts.	Dietary supplement: Pecan SUB; Raw pecan halves with instructions to substitute pecans with isocaloric foods in the habitual diet; Other Names: Pecan

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in baseline fasting blood lipids at 4 weeks and 8 weeks	Total cholesterol (mg/dL), high-density lipoprotein (HDL) cholesterol (mg/dL), triglycerides (mg/dL), low-density lipoprotein (LDL) cholesterol (mg/dL), non-HDL cholesterol (mg/dL), apolipoprotein B (mg/dL)	Baseline, 4 weeks, 8 weeks
Change in baseline lipoprotein(a), lipoprotein particle number, and lipoprotein size at 4 and 8 weeks	Low-density lipoprotein (LDL) particle number (nmol/L), LDL small (nmol/L), LDL medium (nmol/L), HDL large (nmol/L), lipoprotein(a) (nmol/L)	Baseline, 4 weeks, 8 weeks
Change in baseline low-density lipoprotein (LDL) peak size at 4 and 8 weeks	LDL peak size (angstrom)	Baseline, 4 weeks, 8 weeks
Change in baseline weight at 4 and 8 weeks	Weight (kg)	Baseline, 4 weeks, 8 weeks
Change in baseline waist and hip circumference at 4 and 8 weeks	waist and hip circumference (cm)	Baseline, 4 weeks, 8 weeks
Change in baseline total body fat percentage at 4 and 8 weeks	Total body fat percentage (%)	Baseline, 4 weeks, 8 weeks

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in fasting and postprandial peptide YY, cholecystokinin (CCK), and ghrelin from baseline to 8 weeks	Peptide YY (pg/mL), CCK (pg/mL) and ghrelin (pg/mL)	Data will be collected at fasting at baseline, 4 weeks and 8 weeks. Postprandial data will be collected at baseline and 8 weeks.
Change in fasting and postprandial glucose and triglycerides from baseline to 8 weeks	Glucose (mg/dL) and triglycerides (mg/dL)	Data will be collected at fasting at baseline, 4 weeks and 8 weeks. Postprandial data will be collected at baseline and 8 weeks.
Change in fasting and postprandial non-esterified free fatty acids (NEFA) from baseline to 8 weeks	NEFA (mEq/L)	Data will be collected at fasting at baseline, 4 weeks and 8 weeks. Postprandial data will be collected at baseline and 8 weeks.
Change in fasting and postprandial insulin from baseline to 8 weeks	Insulin (uU/mL)	Data will be collected at fasting at baseline, 4 weeks and 8 weeks. Postprandial data will be collected at baseline and 8 weeks.
Change in resting metabolic rate (RMR) from baseline to 8 weeks	RMR (kcals/d) measured via indirect calorimetry	Baseline and 8 weeks
Change in diet induced thermogenesis (DIT) from baseline to 8 weeks	DIT (kcals) measured via indirect calorimetry	Baseline and 8 weeks
Change in fasting and postprandial carbohydrate and fat oxidation from baseline to 8 weeks	Carbohydrate oxidation (g) and fat oxidation (g) measured via indirect calorimetry	Measured at fasting and for 3.5h postprandially at baseline and 8 weeks
Change in diet respiratory exchange ratio (RER) from baseline to 8 weeks	RER measured via indirect calorimetry	Measured at fasting and for 3.5h postprandially at baseline and 8 weeks
Change in fasting and postprandial lipid peroxidation from baseline to 8 weeks	Malondialdehyde (MDA) (uM) measured via Thiobarbituric acid reactive substances (TBARS) assay.	Measured at fasting and for 4 hours postprandially at baseline and 8 weeks
Change in fasting and postprandial total antioxidant capacity from baseline to 8 weeks	Total antioxidant capacity (uM trolox equivalents) measured via Oxygen Radical Absorbance Capacity (ORAC) assay.	Measured at fasting and for 4 hours postprandially at baseline and 8 weeks
Changes in fasting and postprandial hunger and satiety from baseline to 8 weeks	Hunger, fullness, prospective consumption, and desire to eat measured via a Visual Analog Scale (VAS) (mm). The range of scores on the continuous VAS is 0-100 mm. Zero represents no hunger, fullness, prospective consumption, and desire to eat, while 100 represents the greatest feeling of these outcomes.	Measured at fasting and for 4 hours postprandially at baseline and 8 weeks. Also, measured once per hour after the baseline and 8-week visits.

Other Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in baseline perceived stress at 4 and 8 weeks	The perceived stress scale (PSS) measures stress over the last 4 weeks on a scale from 0-40. Low scores indicate low stress. A score of 13 is average. Scores of 20 or greater are considered to be high stress.	Baseline, 4 weeks, 8 weeks

Collaborators and Investigators

• Sponsor: University of Georgia
• Collaborators: Georgia Pecan Commission

Publications and helpful links

General Publications

• Guarneiri LL, Paton CM, Cooper JA. Pecan-Enriched Diets Alter Cholesterol Profiles and Triglycerides in Adults at Risk for Cardiovascular Disease in a Randomized, Controlled Trial. J Nutr. 2021 Oct 1;151(10):3091-3101. doi: 10.1093/jn/nxab248.

Study record dates

Study Major Dates

• Study Start (ACTUAL): August 10, 2018
• Primary Completion (ACTUAL): June 1, 2021
• Study Completion (ACTUAL): June 1, 2021

Study Registration Dates

• First Submitted: April 30, 2020
• First Submitted That Met QC Criteria: May 1, 2020
• First Posted (ACTUAL): May 6, 2020

Study Record Updates

• Last Update Posted (ACTUAL): June 1, 2022
• Last Update Submitted That Met QC Criteria: May 27, 2022
• Last Verified: May 1, 2022

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Metabolic Diseases; Lipid Metabolism Disorders; Hyperlipidemias; Dyslipidemias; Hypercholesterolemia
• Other Study ID Numbers: STUDY00005985

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO
• IPD Plan Description: The plan is to share group averages through publication.

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No