Ageing modifies the effects of beetroot juice supplementation on 24-hour blood pressure variability: An individual participant meta-analysis

Nitric Oxide. 2015 May 1:47:97-105. doi: 10.1016/j.niox.2015.04.007. Epub 2015 Apr 29.


Objectives: Abnormal circadian oscillations of blood pressure (BP) and nocturnal-diurnal BP differences (i.e., dipping) increase cardiovascular risk. Whether inorganic nitrate supplementation influences 24-hr BP variability is currently unknown. We studied the effects of high-nitrate beetroot juice supplementation on BP variability measured by 24-hr ambulatory BP monitoring (24-hr ABPM) in older subjects.

Methods: Data from four independent randomised clinical trials were collated. Eighty-five older participants (age range: 55-76 years) were included in the final database. Two trials had an open-label, parallel design and two trials had a cross-over, double-blind design. Participants were randomised to either beetroot juice or placebo. Changes in 24-hr ABPM (daily, diurnal, nocturnal), variability (weighted-SDs), night-dipping, morning surge for systolic and diastolic BP were measured. Meta-analysis was conducted to obtain pooled estimates of the effect size for each BP outcome. Sub-group analyses were conducted to evaluate the influence of age, BMI, gender, BP status and changes in nitrite concentrations on the effect size.

Results: The pooled effect of beetroot juice on all BP outcomes was not significant. Beetroot juice ingestion determined a significant decrease in nocturnal systolic BP variability in subjects aged less than 65 y (2.8 mmHg, -4.5 -1.0, p = 0.002) compared to the older group (≥ 65 y; 1.0 mmHg, -2.2 4.2, p = 0.54). A greater change in NO2(-) concentrations after beetroot supplementation was associated with significant differences for nocturnal mean (-3.4 mmHg, -0.6 -2.4, p = 0.02) and variability (-0.8 mmHg, -1.5 -0.06, p = 0.03) of systolic BP.

Conclusions: The vascular responsiveness to inorganic nitrate may be modified by mechanisms of vascular ageing influencing the reducing capacity to convert inorganic nitrate into nitrite and tissue-specific responses to dietary nitrate supplementation.

Keywords: Ageing; Ambulatory blood pressure; Beetroot juice; Hypertension; Inorganic nitrate.

Publication types

  • Meta-Analysis
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aged
  • Aging*
  • Beta vulgaris / chemistry*
  • Beverages*
  • Blood Pressure Monitoring, Ambulatory*
  • Blood Pressure*
  • Dietary Supplements*
  • Female
  • Humans
  • Male
  • Middle Aged
  • Nitrates / chemistry
  • Nitrates / metabolism
  • Nitrites / chemistry
  • Nitrites / metabolism
  • Time Factors


  • Nitrates
  • Nitrites