Cardiometabolic Effects of the Recommended Daily Pecan Intake Dose

Official title

Cardiometabolic Effects of the Recommended Daily Pecan Intake Dose: A 12-Week Randomized Controlled Trial

Overview

Cardiovascular disease risk factors, including higher BMIs and poor cholesterol profiles, are on the rise and contribute to the United States' growing disease burden. The bioactive compounds contained in tree nuts have been shown to beneficially affect cardiometabolic health outcomes. Pecans contain more total phenols, sterols, and flavonoids than any other tree nut. They also are a rich source of polyunsaturated fatty acids (PUFAs), fiber, vitamin A, vitamin E, folic acid, calcium, magnesium, phosphorus, potassium, and zinc. These bioactive components in pecans are likely the reason for the previously documented improvements in cardiometabolic health. This study aims to examine the impact of a low dose of pecans on changes in fasting and postprandial lipid metabolism/blood lipids and markers of chronic disease risk. The specific aims of this study are to: * Examine the effect of pecan consumption at a dose of 6% of total energy needs for 12 weeks on fasting and postprandial blood lipids. * Examine the effect of pecan consumption at a dose of 6% of total energy needs for 12 weeks on other markers of chronic disease risk. Participants will be asked to: * Consume pecans daily for 12 weeks or maintain their current habitual diet. * Attend two short visits at 4 and 8 weeks for fasting blood draws, body measurements, and to collect their next 4 weeks' supply of study materials. * Attend two longer (5 h) testing visits, which include eating a standard breakfast meal and having their blood drawn periodically before and after breakfast. Researchers will compare the Pecan and Control groups to examine the physiologic effects of incorporating a low dose of pecans into one's diet.

Detailed description

Accounting for nearly 1 in every 4 deaths in the U.S., cardiovascular disease (CVD) is the leading cause of death for adults. One risk factor for CVD is hypercholesterolemia, which can double the risk for this disease. Research investigating the relationship between pecan nut consumption and cardiometabolic outcomes has shown that pecan nut consumption can significantly benefit fasting and postprandial blood lipids, reduce CVD risk factors, promote weight maintenance, improve subjective and psychological markers of physiological appetite, increase total antioxidant capacity, and increase energy expenditure and fat oxidation. However, the current literature on pecan consumption and health outcomes only encompasses physiological benefits coming from a dosage of \~ 45g/day and above, which is above the current dietary guidelines. Recent evidence from our pecan dose-response study showed that consuming 6% of energy needs from pecans (\~ 21.5 g/day) trended toward reductions in blood lipids but did not reach significance by the end of the short, 4-week intervention. Based on previous interventions with low doses of tree nuts, a longer duration, such as 12 weeks, may be needed to see significant effects. If lower doses of pecans in the diet are found to improve fasting and postprandial lipid metabolism and markers of chronic disease risk, these study findings could lead to improvements in health and possibly provide additional information about dietary guidelines for nut consumption.

This prospective clinical study is a single-blinded, randomized control trial in adults at increased risk for cardiovascular disease (poor cholesterol profiles and/or overweight/obesity). There are two diet interventions: Pecan (6% of energy needs from pecans) and Control (instructed to maintain their current habitual diet, but abstain from any tree nut/peanut consumption and limit nut butters to no more than 2x/wk during the intervention). The study protocol consists of a 12-week intervention that will involve substituting pecans for commonly consumed snack or meal items every day for the entire 12-week intervention or maintaining a current/usual diet.

There are a total of 5 testing visits: screening (v0), pre-intervention (v1), 2 short visits at 4 and 8 weeks (v2, v3), and post-intervention (v4).

At screening (v0), qualification is confirmed based on anthropometrics and a fasting blood draw, which is analyzed for a cholesterol panel and blood glucose. Additionally, energy requirements are estimated at this visit for use in the diet intervention.

At v1, participants will have anthropometrics measured, including body composition by dual-energy x-ray absorptiometry (DXA). Fasting and postprandial blood draws for a 4h period will occur following a high saturated-fat meal challenge which delivers 17% of the participant's estimated energy needs.

12-week dietary intervention: The 12-week diet intervention will consist of research personnel providing pecans that deliver 6% of the participant's daily energy needs (determined at V0). Participants randomized in the pecan group will receive dietary counseling at the baseline (V1) and intervention visits at 4 and 8 weeks (V2-V3) on substituting pecans for isocaloric foods from their habitual diet. Individuals randomized in the control group will be instructed to follow their habitual diet, but avoid any tree nut/peanut consumption and limit nut butter to no more than 2x/wk, and will not be provided with any food items.

Participants return at 4 and 8 weeks (v2, v3) to return study materials and collect pecans for the next four weeks (if applicable). At these mid-intervention visits, participants also have a fasting blood draw and body measures taken.

At the end of the 12-week dietary intervention, participants return for v4, where all procedures from v1 are repeated.

As decided a priori, we will complete a per protocol analysis. The investigators hypothesize that including the daily consumption of pecans will improve the proposed overall health outcomes and markers of chronic disease risk compared to the control group.

Interventions

• Other Pecan
  Participants are provided with a quantity of pecans that delivers 6% of the participant's estimated energy needs for 12 weeks.
• Other Control
  Participants are asked to maintain their current habitual diet and to avoid any tree nut/peanut consumption and limit nut butters to no more than twice per week for the entire 12-week intervention period.

Primary outcome measures

• Change in fasting serum lipoprotein and cholesterol concentrations [Time frame: baseline, 12 weeks]
• Change in fasting and postprandial plasma triglyceride concentrations [Time frame: baseline, 12 weeks]
• Change in fasting and postprandial plasma non-esterified fatty acid (NEFA) concentrations [Time frame: baseline, 12 weeks]
• Change in fasting and postprandial plasma appetite control hormone concentrations [Time frame: baseline, 12 weeks]
• Change in fasting and postprandial subjective feelings related to appetite [Time frame: baseline, 12 weeks]
• Change in fasting and postprandial plasma Malondialdehyde (MDA) [Time frame: baseline, 12 weeks]
• Change in fasting and postprandial plasma total antioxidant capacity [Time frame: baseline, 12 weeks]

Secondary outcome measures (11)

• Change in fasting serum hepatic enzymes [Time frame: baseline, 12 weeks]
• Change in fasting serum hepatic proteins [Time frame: baseline, 12 weeks]
• Change in fasting serum bilirubin [Time frame: baseline, 12 weeks]
• Change in fasting and postprandial plasma insulin concentrations [Time frame: baseline, 12 weeks]
• Change in fasting and postprandial plasma glucose concentrations [Time frame: baseline, 12 weeks]
• Change in fasting inflammatory cytokine concentrations [Time frame: baseline, 12 weeks]
• Change in acute dietary intake [Time frame: baseline, 12 weeks]
• Change in fasting plasma markers of coagulation potential [Time frame: baseline, 12 weeks]
• Change in fasting and postprandial plasma angiopoietin-like (ANGPTL) proteins [Time frame: baseline, 12 weeks]
• Change in fasting insulin resistance metrics [Time frame: baseline, 12 weeks]
• Change in overall liking and desire to consume subjective ratings of the intervention food provided [Time frame: Baseline, Week 1, Week 2, Week 3, Week 4, Week 5, Week 6, Week 7, Week 8, Week 9, Week 10, Week 11, Week 12]

Eligibility criteria

Inclusion criteria

• 25-75 year-old men and women at increased risk for cardiovascular disease. Increased risk for cardiovascular disease will be defined by either elevated cholesterol profiles -or- overweight/obesity.
• Elevated cholesterol profiles will be defined as:
• "Borderline High" and/or "at risk" in two or more of the following variables (total cholesterol: 180-239 mg/dL, LDL cholesterol 110-159 mg/dL, triglycerides 130-199 mg/dL) --or-- "High" in total cholesterol (240 mg/dL and higher), LDL (160 mg/dL or higher), or triglycerides (between 200-350 mg/dL).
• Overweight/obesity will be defined by body mass index (overweight > 28 kg/m2 or obesity 30 kg/m2 or greater).

Exclusion criteria

• Probable familial hypercholesterolemia, defined by: total cholesterol greater than 290 mg/dL or LDL levels greater than 190 mg/dL plus a family history of myocardial infarction (MI) before 50 years of age in a 2nd-degree relative or below age 60 in a 1st-degree relative.
• Women on hormone replacement therapy less than 2 years.
• Women who are pregnant or nursing
• Individuals who regularly exercise more than 3h/w
• Weight gain or loss of more than 5% body weight in the past 3 months
• Plans to begin a weight loss/exercise regimen during the trial
• History of medical or surgical events that could affect digestion or swallowing
• Gastrointestinal surgeries, conditions, or disorders
• Any chronic diseases (including moderate to severe asthma, chronic lung disease, and kidney disease)
• Metabolic disease
• Atherosclerosis
• Previous MI or stroke
• Cancer
• Fasting blood glucose levels greater than 126 mg/dL
• Blood pressure greater than 180/120 mmHg
• Medication use affecting digestion, absorption, or metabolism (e.g. thyroid meds), lipid-lowering medications, medications for diabetes, steroid/hormone therapies, or current antibiotic cycles
• Medically prescribed or special diets
• Food allergies (specific to the foods in the study, including tree nuts, dairy, gluten, palm oil, and coconut oil)
• Fish oil supplements
• Individuals who regularly consume nuts and/or nut butter (defined as consumption of >2 servings (\~56g) of tree nuts, nuts, or nut butter (e.g., peanut butter, almond butter) per week
• Excessive alcohol use (greater than 3 drinks/day for men; greater than 2 drinks/day for women)
• Tobacco or nicotine use
• Underweight BMI (<18.5 kg/m²)

Criteria are shown verbatim from the registry (in English). Final eligibility is always assessed by the study center.

Healthy volunteers: Yes

Study design

Allocation

Randomized

Model

Parallel assignment

Masking

Single blind

Primary purpose

Prevention

Study locations

United States · 1 center

• University of Georgia — Athens

Identifiers

NCT: NCT07696403 · PROJECT00014754

Primary sources (government registries)

• ClinicalTrials.gov (US NIH)

View this study on ClinicalTrials.gov ↗