The Effects of Eggs in a Plant-Based Diet on Oxidative Stress and Inflammation in Metabolic Syndrome

Abstract

We recently reported that the inclusion of whole eggs in plant-based diets (PBD) increased plasma choline, lutein, and zeaxanthin in individuals with metabolic syndrome (MetS). The objective of the current study was to evaluate whether this dietary pattern would protect against oxidative stress and low-grade inflammation, two common characteristics of MetS. We recruited 24 men and women with MetS, who, after following a PBD for 2 weeks (baseline), were randomly allocated to consume either two whole eggs with 70 g of spinach/day (EGG) or the equivalent amount of egg substitute with spinach (SUB) as breakfast for 4 weeks. After a 3-week washout, they were allocated to the alternate breakfast. We measured biomarkers of oxidation and inflammation at baseline and at the end of each intervention. Tumor necrosis factor-alpha, interleukin-6, monocyte protein attractant-1, liver enzymes, and C-reactive protein, as well as total antioxidant capacity, paraoxonase-1 (PON-1) activity, and other biomarkers of oxidation were not different at the end of EGG or SUB or when compared to baseline. However, plasma malondialdehyde (MDA) concentrations were lower (p < 0.05) during the EGG and baseline compared to SUB. In addition, the increases in dietary lutein and zeaxanthin previously observed had a strong positive correlation with PON-1 activity (r = 0.522, p < 0.01) only during the EGG period, whereas plasma zeaxanthin was negatively correlated with MDA (r = −0.437, p < 0.01). The number of participants with MetS was reduced from 24 during screening to 21, 13, and 17 during the BL, EGG, and SUB periods, respectively, indicating that eggs were more effective in reversing the characteristics of MetS. These data suggest that adding eggs to a PBD does not detrimentally affect inflammation or oxidative stress; on the contrary, eggs seem to provide additional protection against the biomarkers that define MetS.