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.
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
Allocation
RANDOMIZED
Purpose
OTHER
Masking
SINGLE
Enrollment
124
University of Georgia- Department of Foods and Nutrition
Athens, Georgia, United States
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)
Time frame: 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)
Time frame: Baseline, 4 weeks, 8 weeks
Change in baseline low-density lipoprotein (LDL) peak size at 4 and 8 weeks
LDL peak size (angstrom)
Time frame: Baseline, 4 weeks, 8 weeks
Change in baseline weight at 4 and 8 weeks
Weight (kg)
Time frame: Baseline, 4 weeks, 8 weeks
Change in baseline waist and hip circumference at 4 and 8 weeks
waist and hip circumference (cm)
Time frame: Baseline, 4 weeks, 8 weeks
Change in baseline total body fat percentage at 4 and 8 weeks
Total body fat percentage (%)
Time frame: Baseline, 4 weeks, 8 weeks
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)
Time frame: Data will be collected at fasting at baseline, 4 weeks and 8 weeks. Postprandial data will be collected at baseline and 8 weeks.
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Change in fasting and postprandial glucose and triglycerides from baseline to 8 weeks
Glucose (mg/dL) and triglycerides (mg/dL)
Time frame: 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)
Time frame: 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)
Time frame: 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
Time frame: Baseline and 8 weeks
Change in diet induced thermogenesis (DIT) from baseline to 8 weeks
DIT (kcals) measured via indirect calorimetry
Time frame: 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
Time frame: 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
Time frame: 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.
Time frame: 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.
Time frame: 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.
Time frame: 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.