Aging and Chronic Disease
Objectives: Evidence from observational and intervention studies has shown a high intake of tree nuts is associated with a reduced risk of cardiovascular disease (CVD), mortality from type 2 diabetes (T2DM), and all-cause mortality. While most randomized clinical trials to date have focused on the beneficial effect of nuts on plasma lipids in subjects with hypercholesterolemia, and some on glycemic control in T2DM patients, there is limited evidence of their effects in other at-risk populations or indicators of CVD risk. We hypothesized the daily consumption of a diet including whole pecans will attenuate changes in biomarkers associated with cardiometabolic disease risk in otherwise healthy, middle-aged and older adults (≥45y) who are overweight or obese (BMI 25-35) with central adiposity.
Methods: We conducted a randomized, controlled crossover feeding trial (n=26) to compare the effects of a typical American diet including ~1.5 oz/d pecans (15% kcal) with an isocaloric control diet similar in total fat and fiber content, but absent nuts.
Results: After 4 wk, favorable changes in serum insulin levels, insulin resistance (HOMA-IR) and beta cell function (HOMA-β) were greater with pecans vs. control diet (P=0.02, 0.04, 0.02, respectively). Although total and LDL cholesterol were lower following the pecan diet, their magnitude of change vs. the control diet was borderline (P=0.056, 0.067, respectively). Other biomarkers of cardiometabolic risk, including serum glucose and systolic/diastolic blood pressure, were also lower with the pecan diet but not statistically different. A multivariate multilevel model was used to simultaneously analyze change in z-scores of insulin, glucose, total cholesterol, triglycerides, and LDL. An analysis of the aggregate change yielded a mean -0.14 standard deviations (SD) with the pecan-rich diet and +0.25 SD with the control diet (mean difference of 0.39 SD between groups, P = 0.009). Thus, when compared with the control diet, pecans had a significant effect on several biomarkers of cardiometabolic risk.
Conclusions: This study suggests displacing a portion of the saturated fat from a typical American diet with a small handful of whole pecans daily, can protect middle-aged and older adults at high risk of CVD and T2DM associated with overweight and obesity.