Overview
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.
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.
Eligibility
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