Postprandial Vascular Responses to a High Fat Meal in Centrally Obese Adults

Abstract

High fat meals have been implicated as a contributor to obesity and associated cardiovascular disease risk. Such meals may adversely affect vascular properties for hours after ingestion, which presumably leads to long-term vascular impairment. PURPOSE:Examine pre and postprandial arterial stiffness and endothelial function in response to a high fat meal and the effects of fitness and body composition on these responses. METHODS:Sixty-six subjects (age: 48 ± 9 yrs; 51 F, 13 M; BMI: 34.8 ± 3.8; waist circumference: 102 ± 11 cm) were examined at baseline (fasting) and 4 hours after consuming a McDonald's breakfast (900 calories, 50 grams of fat). Using the EndoPat 2000, arterial stiffness was measured by fingertip tonometry derived augmentation index (AI); endothelial function was measured by fingertip plethysmography that reflects the forearm blood flow dilation response to brachial artery occlusion and release, which yields a reactive hyperemia index (RHI). Subjects also underwent fitness testing on a treadmill to determine maximal oxygen capacity (VO2max) and general and central obesity was determined by dual energy x-ray absorptiometry. RESULTS: Fasting BP was 124 ± 14 / 74 ± 10 mm Hg; HR: 66 ± 10 bpm; RHI: 2.3 ± 0.5 %; and AI, 17.2 ± 15.2 %. RHI and HR were unchanged, whereas AI fell to 10.3 ± 14.5 % (p< 0.01) in response to the meal. In a bivariate analysis, a lower postprandial AI was associated with younger age (r=0.50, p<0.01), higher VO2max (r=-0.34, p<0.05) and lower total percent body fat (r=0.25, p=0.05). No association was found between postprandial AI with RHI, or markers of central obesity. Using a multivariate regression model that included sex, baseline AI emerged as the only independent predictor of postprandial AI. CONCLUSIONS: A high fat meal did not worsen resistance vessel endothelial function, whereas arterial stiffness was markedly reduced. These data suggest that a high-fat meal results in acute changes in vascular tone, which is influenced by baseline arterial stiffness but is independent of age, fitness, and fatness.