Ingestion of Broccoli Sprouts Does Not Improve Endothelial Function in Humans with Hypertension

Buris Christiansen,Helena Domínguez,Jens Christian Sørensen,Atheline Major Petersen,Nikolaj Ihlemann,Hermann Thomas,Lars Køber,Britt Kveiborg,Hilmer Sørensen,Christian Torp-Pedersen,Christian Rask Madsen,Natalia Bellostas Muguerza,Graham Pockley

doi:10.1371/journal.pone.0012461

Abstract

Ingestion of glucosinolates has previously been reported to improve endothelial function in spontaneously hypertensive rats, possibly because of an increase in NO availability in the endothelium due to an attenuation of oxidative stress; in our study we tried to see if this also would be the case in humans suffering from essential hypertension.Methods40 hypertensive individuals without diabetes and with normal levels of cholesterol were examined. The participants were randomized either to ingest 10 g dried broccoli sprouts, a natural donor of glucosinolates with high in vitro antioxidative potential, for a 4 week period or to continue their ordinary diet and act as controls. Blood pressure, endothelial function measured by flow mediated dilation (FMD) and blood samples were obtained from the participants every other week and the content of glucosinolates was measured before and after the study. Measurements were blinded to treatment allocation.ResultsIn the interventional group overall FMD increased from 4% to 5.8% in the interventional group whereas in the control group FMD was stable (4% at baseline and 3.9% at the end of the study). The change in FMD in the interventional group was mainly due to a marked change in FMD in two participants while the other participants did not have marked changes in FMD. The observed differences were not statistically significant. Likewise significant changes in blood pressure or blood samples were not detected between or within groups. Diastolic blood pressure stayed essentially unchanged in both groups, while the systolic blood pressure showed a small non significant decrease (9 mm Hg) in the interventional group from a value of 153 mm Hg at start.ConclusionDaily ingestion of 10 g dried broccoli sprouts does not improve endothelial function in the presence of hypertension in humans.Trial RegistrationClinicaltrials.gov NCT00252018

Highlights

Oxidative stress is considered to play a important role in the processes of cellular injury which leads to the development of atherosclerosis.[1]
We have focused on endothelial function since this parameter previously has been demonstrated to be influenced by the level of oxidative stress, and because it is a sensitive predictor for oxidative stress as well as for the future development of atherosclerosis.[9,10]
Following the hypothesis outlined in the introduction our primary outcome was if we would observe an increase in flow mediated dilation (FMD) in the interventional group during the intervention.Secondary outcomes were changes in blood pressure and changes in levels of blood cholesterol during the study in the interventional group

Summary

Introduction

Oxidative stress is considered to play a important role in the processes of cellular injury which leads to the development of atherosclerosis.[1]. A group of substances which might have this effect are the glucosinolates, substances naturally occurring in cruciferous plants; the glucosinolates are precursors to isothiocyanates, of which sulphoraphane is one of the most potent inducers of the expression of phase-2-enzymes, in mammalian cells.[5,6,7]. Among the enzymes induced in vitro the gluthation-S-reductase may be of particular interest since it is instrumental in recycling gluthathion to its reduced state in the cell. In vitro studies have demonstrated the beneficial effects of glucosinolates on mammalian cell lines[7]. Wu and colleagues demonstrated that daily treatment of Stroke Prone Hypertensive rats with dried broccoli sprouts after weaning attenuated the development of hypertension and improved endothelial function of the carotid arteries.[8]

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