The Effects of Diets on Vulnerability to Oscillatory Shear Stress-Induced Endothelial Dysfunction

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Etwaroo, Raelisa
Endothelial function , Plant-based diets , Flow mediated dilation (FMD) , Oscillatory shear stress (OSS)
Endothelial cells line the walls of the arteries, and the proper function of these cells is essential for maintaining arterial health. Endothelial cells allow the widening of blood vessels (vasodilation) in response to blood flow-associated shear stress (frictional force of blood on artery wall) in a response called flow-mediated dilation (FMD). Oscillatory shear stress (OSS), characterized by low mean shear and retrograde shear stress, occurs in regions of the artery that are curved and branched and results in endothelial dysfunction and increased risk of plaque formation due to increased levels of highly reactive molecules (oxidative stress). No study has explored the impact of chronic dietary antioxidant intake on OSS-induced endothelial dysfunction. The purpose of the study reported in Chapter 3 was to investigate whether high dietary intake of antioxidants confers protection from transient OSS exposure-induced endothelial dysfunction. We hypothesized that diets high in antioxidants indicated by high vitamin C and E intake and a high frequency of fruit and vegetable consumption would be associated with a smaller decline in FMD following transient OSS exposure. Fifteen healthy males (22± 3 years [Mean ± SD]) participated in an experimental visit in which brachial artery FMD was assessed with ultrasound before and after 30 min of OSS exposure induced with mild forearm cuff occlusion. Dietary antioxidant content was estimated from the food tracking app Keenoa (vitamin C and E intake over three days) and frequency of fruit and vegetable intake via a food frequency questionnaire. OSS exposure resulted in a significant decline in FMD (pre 9.9% ± 3.5% vs. post 7.2% ± 3.6% p=<0.001). No relationship was found between the magnitude of post-OSS FMD impairment and either antioxidant vitamin intake (r2= 0.01; p= 0.723) or frequency of fruit and vegetable consumption (r2 = 0.005; p=0.809). These preliminary findings suggest that higher dietary antioxidant intake may not be associated with protection from OSS-induced endothelial dysfunction in healthy young men. However, further research in additional populations with more precise quantification of antioxidant intake and blood levels of antioxidants and estimates of oxidative stress is required to make a more definitive conclusion.
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