Co-ingestion of whole eggs or egg whites with glucose protects against postprandial hyperglycaemia-induced oxidative stress and dysregulated arginine metabolism in association with improved vascular endothelial function in prediabetic men

Abstract

Replacing a portion of a glucose challenge with whole eggs (EGG) or egg whites (WHITE) was shown to protect against glucose-induced impairments in vascular function. We hypothesised in the present study that previously observed vasoprotection following co-ingestion of EGG or WHITE with glucose was attributed to limiting postprandial hyperglycaemia-induced oxidative stress that improves NO∙ bioavailability. Prediabetic men completed a randomised, cross-over study in which they ingested isoenergetic meals containing 100 g glucose (GLU), or 75 g glucose with 1·5 EGG, seven WHITE or two egg yolks (YOLK). At 30 min intervals for 3 h, we assessed plasma NO∙ metabolites, the lipid peroxidation biomarker malondialdehyde, antioxidants, arginine and its methylated metabolites (asymmetric dimethylarginine and symmetric dimethylarginine), tetrahydrobiopterin redox status, vasoconstrictors and inflammatory markers. Compared with GLU, malondialdehyde was lower and NO∙ metabolites were greater in EGG and WHITE, but YOLK was not different from GLU. Malondialdehyde was inversely correlated with NO∙ metabolites and vascular function, whereas NO∙ metabolites were positively correlated with vascular function. Compared with GLU, arginine was greater, but asymmetric and symmetric dimethylarginine and angiotensin-II were lower in all egg-based meals. Antioxidants, tetrahydrobiopterin redox status and inflammatory markers did not differ among treatments. Thus, while each egg-based meal improved arginine metabolism, only EGG and WHITE limited lipid peroxidation. This suggests that vasoprotection mediated by EGG and WHITE likely occurs in an NO∙-dependent manner by improving arginine metabolism and attenuating oxidative stress that otherwise limit NO∙ biosynthesis and bioavailability to the vascular endothelium.

The Postprandial Appearance of Features of Cardiometabolic Risk: Acute Induction and Prevention by Nutrients and Other Dietary Substances

“…It would be interesting to further clarify the degree to which certain nutrients (e.g., some amino acids) and other substances (in particular various polyphenols) affect potential underlying mechanisms that are directly or indirectly related to oxidative stress, including NO and nitroso-compound metabolism, induction of the antioxidant defense system, the delicate redox status in tissues, and insulin-related signaling pathways [203,210,211,212,213]. Further studies could also profitably investigate acute variations in the metabolism of arginine and related compounds (such as homoarginine and methylated arginine) during the postprandial period, and their potential modulation by the nature of the meal [214,215].…”

Eggs: Healthy or Risky? A Review of Evidence from High Quality Studies on Hen’s Eggs

“…Similarly, RCT based on daily egg intake found no adverse effects on markers of inflammation or oxidative stress [ 72 , 73 , 120 ]. Indeed, adding whole eggs or egg white to a glucose dietary challenge in prediabetic men attenuated post-prandial oxidative stress [ 121 ].…”

A Protein/Lipid Preload Attenuates Glucose-Induced Endothelial Dysfunction in Individuals with Abnormal Glucose Tolerance

“…In fact, a reduction in arginine availability through increased arginase activity impairs NO production in T2D [11,49], while arginase inhibition ameliorates endothelial function [50]. Furthermore, the lack of the glucose-induced decline of plasma arginine when fructose-rather than glucose-is ingested [10] or when a small amount of protein is co-ingested with glucose [51] has been hypothesized to be responsible for the lesser impact of the oral load on endothelial function. Finally, the increase in plasma arginine might also counterbalance the rise in asymmetric dimethylarginine (ADMA) observed after glucose ingestion in subjects with AGT [52].…”