Diets Enriched With Pecans

Study Overview
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Brief Summary
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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.

Detailed Description
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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.

Official Title
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Comparison of Health Effects of Diets With and Without Pecans

Conditions
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Hypercholesterolemia, Obesity

Intervention / Treatment
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* Dietary Supplement: Pecan ADD
* Dietary Supplement: Pecan SUB


Participation Criteria
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Eligibility Criteria
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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

Ages Eligible for Study
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Minimum Age: 30 Years
Maximum Age: 75 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Other
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Single


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| No Intervention: Control<br>Participants in this group avoid all nuts for 8 weeks. | |
| Experimental: Pecan ADD<br>Participants in this group consume 68 g of pecans/d with no additional dietary instructions and avoid all other nuts. | Dietary Supplement: Pecan ADD<br>* Raw pecan halves without dietary substitution instructions<br>* Other names: Pecan;|
| Experimental: Pecan SUB<br>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<br>* Raw pecan halves with instructions to substitute pecans with isocaloric foods in the habitual diet<br>* Other names: Pecan;|

What is the study measuring?
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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. |