Assessment of vascular and endothelial dysfunction in nutritional studies.

Vascular and endothelial dysfunction (VED) is emerging as a potential set of early markers of cardiovascular disease risk and tests for its measurement have been widely used in clinical research. The aim of this viewpoint is to describe and discuss the current usage of these measures in well-designed nutritional trials, using the potential relationship between fruit juice intake and VED as example. A search was conducted using the NHS evidence portal including studies published in English between January 1980 and October 2013. Only 10 suitable studies were selected, which investigated the effect of fruit juice intake on VED, among which 4 interventions used flow-mediated dilatation, 2 arterial stiffness, 2 a combination of arterial stiffness and flow-mediated dilatation, 2 carotid intimal media thickness and 1 iontophoresis with laser Doppler. Despite minimal effects reported on classical CVD markers, such as lipids, 8 out of the 10 identified studies reported an effect on endothelial function following juice consumption, indicating that VED tests can be effectively used in human dietary interventions to identify relationships between bioactive compounds from fruit and CVD risk. However, paucity of available data, scarcity of compound bioavailability and metabolism information, strong heterogeneity among experimental methodologies and a number of limitations to study designs, still limit the interpretation of the results obtained through these measures. Future, well-designed studies with greater attention to consider use of VED measures are needed to strengthen the utility of VED tests in nutrition research such as those investigating the impact of polyphenol-rich juices and CVD risk.