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Journal of Human Hypertension (2015) 29, 511513 2015 Macmillan Publishers Limited All rights reserved 0950-9240/15
http://www.nature.com/jhh
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RESEARCH LETTER
Effects of beetroot juice supplementation on microvascular blood ow in older overweight and obese subjects: a pilot randomised controlled study
Journal of Human Hypertension (2015) 29, 511513; doi:http://dx.doi.org/10.1038/jhh.2014.114
Web End =10.1038/ http://dx.doi.org/10.1038/jhh.2014.114
Web End =jhh.2014.114 ; published online 4 December 2014
Twenty-one older, overweight participants were randomised to 3 weeks of either beetroot juice concentrate or black-currant juice supplementation to test the effects on cutaneous microvascular reactivity during post-occlusive reactive hyperaemia (PORH). The study also tested whether the effects were maintained after 1 week from interrupting the supplementation. The peak hyperaemic blood ow and the PORH index were not different between the two interventions at the end of both supplementation and post-supplementation phases.
Nitric oxide (NO) is secreted by endothelial cells to regulate vascular tone, platelet aggregation, monocytes adhesion and smooth muscle proliferation.1 Inorganic nitrate improves vascular function and the benecial effect appears to be primarily mediated by a non-enzymatic conversion of inorganic nitrate into NO.2
Previous studies have shown that inorganic nitrate or beetroot supplementation is linked to a signicant improvement of endothelial function (EF). However, the majority of these studies were conducted in healthy young subjects.35 Two recent trials testing the effects of inorganic nitrate in older subjects have reported contrasting effects on EF.6,7
The aims of this study were to examine whether a 3-week beetroot juice supplementation determined an improvement in microvascular reactivity in older overweight participants and to investigate whether changes in microvascular reactivity were maintained after interruption of beetroot supplementation for 1 week.
This was a 28-day open-label randomised controlled trial recruiting non-smoking male and female participants aged 5570 years and with a body mass index (BMI) ranging 2540 kg m2. The study was approved by the Newcastle University-Faculty of Medical Sciences Ethics Committee (Application No = 00628/2013). Written informed consent was obtained from all participants before the study.
Participants were randomised to 3 weeks of either 70 ml of beetroot juice concentrate (Beet-It Sport Shot, James White Ltd, Ipswich, UK) or blackcurrant juice drink (200 ml, Capri-Sun, Uxbridge, UK) as a control. The beetroot juice contains ~ 300 400 mg of nitrate per bottle, whereas the nitrate content...