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Abstract
Cardiovascular disease (CVD) is the leading cause of death in America; however, altering the diet to optimize blood lipids, antioxidant status, and body weight may reduce CVD risk. Previous research has shown that daily pecan consumption improves blood lipids and antioxidant status in healthy populations, but its impact in a population at-risk for CVD is unknown. Furthermore, no study has investigated the impact of daily pecan consumption, with and without dietary substitution instructions, on body weight and other health outcomes. The objective was to investigate the impact of pecan-enriched diets on CVD rick factors including blood lipids, angiopoietin-like proteins (ANGPTL), appetite, metabolism, antioxidant status, and body weight. We conducted an 8-week randomized, controlled trial with two pecan groups and a nut-free control group. The ADD group consumed pecans as part of a free-living diet, and the SUB group substituted the pecans for isocaloric foods from their habitual diet. For the first 5 manuscripts (chapters 3-7), we recruited adults at-risk for CVD. For the 6th manuscript (chapter 8), we made the a priori decision to increase sample size and expand the inclusion criteria to obtain adequate power to investigate the impact of pecan-enriched diets on weight outcomes. In manuscript #1 (chapter 3), total cholesterol, low-density lipoprotein cholesterol, triglycerides, and apolipoprotein-B improved in ADD and SUB with no changes in control. In manuscript #2 (chapter 4), postprandial ANGPTL3 improved in ADD and SUB with no changes in control. In manuscript #3 (chapter 5), postprandial CCK, PYY, ghrelin, and subjective markers of appetite improved in ADD but not SUB or control. In manuscript #4 (chapter 6), resting metabolic rate, fasting fat oxidation, and fasting respiratory exchange ratio improved in SUB. In addition, postprandial diet induced thermogenesis increased in ADD with no changes in SUB or control. In manuscript #5 (chapter 7), both pecan-enriched diets improved postprandial lipid peroxidation and total antioxidant capacity with no changes in control. Altogether, the results of the first five manuscripts suggest that daily pecan consumption may reduce risk for developing CVD. Finally, in manuscript #6 (chapter 8), daily pecan consumption did not result in significant weight gain.