Effects of acute and chronic nuts consumption on energy metabolism: a systematic review of randomised clinical trials

Effects of Hazelnut Consumption on Cardiometabolic Risk Factors and Acceptance: A Systematic Review

Despite being rich sources of monounsaturated fat and a number of vitamins, minerals, and phytonutrients, hazelnuts have received less attention than some other nut types. A qualitative systematic review was carried out to determine the effects of hazelnut consumption on acceptance and markers of cardiometabolic health, including blood lipids and lipoproteins, apolipoproteins A1 and B100, body weight and composition, blood pressure, glycemia, antioxidant status, oxidative stress, inflammation, and endothelial function. In total, 22 intervention studies (25 publications) met our inclusion criteria. The findings indicate some improvements in cardiometabolic risk factors; however, limitations in study design mean interpretation is problematic. The inclusion of hazelnuts in the diet did not adversely affect body weight and composition. Acceptance of hazelnuts remained stable over time confirming nut consumption guidelines are feasible and sustainable. Future studies using more robust study designs in a variety of populations are required to draw more definitive conclusions on the health benefits of hazelnut consumption.

Effect of Brazil Nuts on Selenium Status, Blood Lipids, and Biomarkers of Oxidative Stress and Inflammation: A Systematic Review and Meta-Analysis of Randomized Clinical Trials

Tree nuts, including Brazil nuts, have been hypothesized to impact cardiovascular health through the modulation of oxidative stress and inflammation. Nonetheless, a quantitative analysis of these effects has not been performed. Therefore, the aim of this study was to systematically revise and quantify the effect of Brazil nut intervention on selenium status, blood lipids, and biomarkers of oxidative stress and inflammation using a meta-analytical approach. To meet the goals of this study, a systematic search of PubMed, EMBASE, and Web of Science databases of published randomised clinical trials reporting on dietary interventions with Brazil nuts and their effects on selenium status, blood lipids, and markers of oxidative stress and inflammation was performed. Eight articles were included for systematic review and meta-analysis. Based on the conducted analysis, a significant positive effect of Brazil nuts on selenium blood concentration (SMD = 6.93, 95% CI: 3.99; 9.87) was found. Additionally, a positive effect of Brazil nut intervention on glutathione peroxidase activity (SMD = 0.53, 95% CI: 0.07; 0.99) was observed. However, no significant results were found when considering blood lipid levels, including results for total cholesterol (SMD = −0.22, 95% CI: −0.57; 0.14), HDL cholesterol (SMD = −0.04, 95% CI: −0.28; 0.19) and LDL cholesterol (SMD = −0.15; 95% CI: −0.43; 0.13). In conclusion, the findings from this study suggest that Brazil nut consumption improves selenium status and exerts antioxidant effects, which could be considered a potential pathway for the prevention of metabolic disorders related to altered blood lipid profiles. However, further studies are needed to elucidate the effect of Brazil nuts toward blood lipid profile, also preferably controlling for other biomarkers.