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European Journal of Nutrition

, Volume 55, Issue 2, pp 451–459 | Cite as

Effects of inorganic nitrate and beetroot supplementation on endothelial function: a systematic review and meta-analysis

  • Jose Lara
  • Ammar W. Ashor
  • C. Oggioni
  • A. Ahluwalia
  • John C. Mathers
  • Mario Siervo
Original Contribution

Abstract

Background

Diets rich in inorganic nitrate are associated with lower blood pressure, an effect that may be mediated by an improvement of endothelial function (EF). Therefore, a systematic review and meta-analysis of randomised controlled trials (RCTs) were conducted to examine the effects of inorganic nitrate and beetroot supplementation on measures of EF.

Methods

MEDLINE, EMBASE and Scopus databases were searched from inception until November 2014. Specific inclusion criteria were as follows: (1) RCTs; (2) trials comparing inorganic nitrate or beetroot supplementation with placebo control groups; and (3) trials reporting effects of these interventions on outcomes of vascular function. Random-effect models were used to assess the pooled effect sizes showed as standardised mean differences (SMD).

Results

Nine crossover trials and three parallel trials met our inclusion criteria. The trials were conducted between 2008 and 2014 and included a total of 246 participants with 10–64 participants per study. The duration of each intervention ranged from 1.5 h to 28 days. Inorganic nitrate and beetroot consumption was associated with an improvement in vascular function (SMD 0.36; 95 % CI 0.16, 0.56; P < 0.001). The effect on EF was significantly associated with the dose of inorganic nitrate (β = 0.04, SE = 0.01, P < 0.001), age (β = −0.01, SE = 0.004, P = 0.02), baseline BMI (β = −0.04, SE = 0.02, P = 0.05) and systolic BP (β = −0.01, SE = 0.005, P = 0.02).

Conclusions

Inorganic nitrate and beetroot supplementation was associated with beneficial effects on EF. These effects appear to be reduced in older subjects and in subjects with greater cardiometabolic risk.

Keywords

Endothelial function Flow-mediated dilation Beetroot Inorganic nitrate Meta-analysis Cardiovascular risk 

Notes

Conflict of interest

There are no competing financial interests.

Supplementary material

394_2015_872_MOESM1_ESM.docx (51 kb)
Supplementary material 1 (DOCX 50 kb)
394_2015_872_MOESM2_ESM.xlsx (17 kb)
Supplementary material 2 (XLSX 17 kb)

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Copyright information

© Springer-Verlag Berlin Heidelberg 2015

Authors and Affiliations

  • Jose Lara
    • 1
  • Ammar W. Ashor
    • 1
    • 2
  • C. Oggioni
    • 1
  • A. Ahluwalia
    • 3
  • John C. Mathers
    • 1
  • Mario Siervo
    • 1
  1. 1.Human Nutrition Research Centre, Institute of Cellular MedicineNewcastle UniversityNewcastle upon TyneUK
  2. 2.College of MedicineUniversity of Al-MustansiriyahBaghdadIraq
  3. 3.William Harvey Research Institute, Barts and The London Medical SchoolQueen Mary University of LondonLondonUK

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