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Nitrate-Rich Beetroot Juice Reduces Blood Pressure in Tanzanian Adults with Elevated Blood Pressure: A Double-Blind Randomized Controlled Feasibility Trial

Lookup NU author(s): Dr Mario Siervo, Dr Oliver Shannon, Professor Bloss Stephan, Dr Keith Gray, Dr Stella PaddickORCiD

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This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).


Abstract

Background: In Sub-Saharan Africa, current strategies are struggling to control the burgeoning hypertension epidemic. Dietary interventions such as inorganic nitrate or folic acid supplementation could represent promising strategies for reducing blood pressure (BP) in this setting. Objectives: This feasibility study explores the effects of dietary inorganic nitrate supplementation, alone or in combination with folic acid, on BP in Tanzanian adults with elevated BP in Tanzania. Methods: A placebo-controlled, double-blind, randomized controlled feasibility trial was conducted. Forty-seven middle-aged and older participants (age: 50–70 y, BMI: 26.3–29.1 kg/m2) were randomly assigned to 3 conditions for a period of 60 d: 1) high-nitrate beetroot juice (∼400 mg nitrate) and folic acid (∼5 mg folic acid) (N + F), 2) high-nitrate beetroot juice and placebo (N + P), or 3) nitrate-depleted beetroot juice and placebo (P + P). Clinic and 24-h ambulatory BP and measurements of compliance in plasma (nitrate and folate concentrations) and saliva (nitrate and nitrite) were obtained at baseline, 30 d, and 60 d. Results: Baseline resting systolic and diastolic BP (mean ± SD) was 151.0 ± 19.4 mm Hg and 91.8 ± 11.7 mm Hg, respectively. Compliance to the interventions was high (>90%) in all groups which was confirmed by the significant increase in nitrate and folic acid concentrations in plasma and saliva samples in the treatment arms. After 60 d, 24-h systolic BP dropped by −10.8 ± 9.8 mm Hg (P < 0.001), −6.1 ± 13.2 mm Hg (P = 0.03), and −0.3 ± 9.7 mm Hg (P = 0.83) in the N + P, N + F, and P + P groups, respectively. There was a significant decrease in 24-h diastolic BP in the N + P group (−5.4 ± 5.0 mm Hg, P = 0.004), whereas changes were not significant in the N + F (−1.8 ± 8.1 mm Hg, P = 0.32) and P + P (1.6 ± 8.3 mm Hg, P = 0.43) groups. Conclusions: Dietary inorganic nitrate represents a potential nutritional strategy to lessen the hypertension epidemic in Sub-Saharan Africa. These findings support the rationale for future long-term investigations exploring the efficacy of dietary nitrate for lowering BP and attenuating cardiovascular disease risk in this setting. This trial was registered at isrctn.com as ISRCTN67978523.


Publication metadata

Author(s): Siervo M, Shannon O, Kandhari N, Prabhakar M, Fostier W, Köchl C, Rogathi J, Temu G, Stephan BCM, Gray WK, Haule I, Paddick SM, Mmbaga BT, Walker R

Publication type: Article

Publication status: Published

Journal: Journal of Nutrition

Year: 2020

Volume: 150

Issue: 9

Pages: 2460-2468

Print publication date: 01/09/2020

Online publication date: 30/07/2020

Acceptance date: 21/05/2020

Date deposited: 13/08/2020

ISSN (print): 0022-3166

ISSN (electronic): 1541-6100

Publisher: Oxford University Press

URL: https://doi.org/10.1093/jn/nxaa170

DOI: 10.1093/jn/nxaa170


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