Low quality, high-fat diets are known to be associated with the development of atherosclerosis over a life time. A high-fat meal has been shown to acutely impair macrovascular health, but the impact on microvascular function is not known. The objective of this study was to assess the acute effects of a single high-fat meal on microvascular function, a barometer of vascular health.
Healthy, non-smoking subjects free of cardiovascular disease were recruited. Using brachial artery ultrasound, microvascular endothelial function was assessed by hyperemic velocity time integral (VTI) while macrovascular endothelial function was assessed by flow-mediated dilation (FMD). In a randomized crossover design, subjects were fed a high-fat commercial breakfast meal (50g of fat) on the ‘meal day', receiving endothelial function assessment pre-prandial and reassessment 2 hours postprandial. On the ‘control day', subjects received the same assessments of endothelial function without the high-fat meal. The difference between vascular function measures pre- and post-meal vs the difference in measures on the ‘control day' was assessed.
Twenty healthy subjects (mean age 22.9 ± 4.8 years, 8 females) with mean BP of 108/69 mmHg and mean fasting LDL of 2.37 ± 0.58 mmol/L were included in this study. Paired student t test showed that VTI decreased from 147 ± 38 cm fasting to 122 ± 28 cm post-prandially on the ‘meal day' (p=0.010). This was significantly different from the ‘control day' (VTI 134 ± 36 to 134 ± 28 cm at second measure) (p-value for differences between the two days = 0.040). Analysis of FMD revealed no significant changes between conditions (p=0.273).
Our results suggest that a single high-fat meal affects the microvascular bed, impairing VTI, but not FMD. This suggests that the association between a high fat diet and atherosclerosis may be due to impairment of the microvascular bed, an impact that can be seen in an acute time frame.
© 2012 Canadian Cardiovascular Society. Published by Elsevier Inc. All rights reserved.