Cardiometabolic Effects of the Recommended Daily Pecan Intake Dose

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.