Comparison of two feeding regimens on endothelial function variability measured by peripheral arterial tonometry

Abstract

Consumption of a high-fat meal has been shown to elicit endothelial dysfunction that contributes to cardiovascular events. The US diet pattern of frequent meals and snacks extends the postprandial state. The focus of this research was to optimize a feeding model to study the acute effects of two high-fat meals on endothelial-dependent vasodilation (reactive hyperemia index) and a biomarker of oxidative stress. The study was conducted to compare changes in endothelial function induced by two different feeding regimens (standard feeding regimen and body surface area-based feeding regimen) and to study the peripheral vascular function in the extended postprandial state. A 2 × 4 within subject design was used to investigate variability in reactive hyperemia index and oxidative stress. Ten male subjects (age 19-30 years, BMI 18.5-24.9 kg/m2, Body surface area 1.5-2.2 m2) were recruited and assigned to two feeding regimens, in random order, on different days, with a 1-week washout period. Each feeding regimen contained two meals that were consumed as “breakfast” (0h) and “lunch” (4h) on the test day. Each meal in feeding regimen 1 provided 850 kilocalories; whereas, each meal in feeding regimen 2 provided 460 kilocalorie/m2 subject body surface area. Reactive hyperemia index was measured, followed by blood draw at 0, 2, 4, 6 hours. Blood was analyzed for plasma malondialdehyde as a measure of oxidative stress. Blood glucose and triglyceride were measured to monitor the postprandial response at 0, 1, 2, 3, 4, 5, 6 hours. Power was too low to detect a significant difference in regimen × time interaction and main effect of feeding regimen for reactive iv hyperemia index and oxidative stress (p>0.05, 1-β<0.6). However, the feeding regimen based on body surface area might be a more effective model to use than the standard meal as shown by the greater effect size (ηp2 and ω2). More subjects are needed to confirm this finding. Reactive hyperemia index increased from the fasting state to the postprandial state (p<0.05). Oxidative stress was elevated 2 hours after “breakfast” (p<0.05) and decreased by 4 hours after “breakfast” (p<0.05).