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Protocol and recruitment results from a 13-week randomized controlled trial comparing the effects of different doses of nitrate-rich beetroot juice on cognition, cerebral blood flow and peripheral vascular function in overweight and obese older people

Lookup NU author(s): Abrar Babateen, Dr Sofia Rubele, Dr Oliver Shannon, Dr Ed Okello, Dr Gerry O'BrienORCiD, Professor John Mathers, Dr Mario Siervo



This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License (CC BY-NC-ND).


Background: Nitrate-rich food can increase NO production and may induce positive effects on brain function. This study examined the feasibility of a randomized clinical trial (RCT) testing the effects of prolonged consumption of incremental doses of dietary nitrate (NO3-) in overweight and obese older participants. Secondary aims tested dose-dependent changes in cognitive, vascular and pulmonary functions and cerebral blood flow (CBF).Methods: This was a single blind, four-arm parallel RCT conducted in 60 overweight and obese older participants. Eligible participants were randomized to:1) high NO3- (140ml of beetroot juice (BJ) per day, ~800mg of NO3-/day), 2) moderate NO3- (70ml of BJ per day, ~400mg of NO3-/day), 3) low NO3- (70ml on alternate days, ~400mg of NO3-) or 4) NO3- depleted (70ml on alternate days, ~0.001mg of NO3). Measurements of cognitive, vascular and pulmonary functions and CBF were conducted at baseline and 13-weeks. NO3- intake was assessed by six 24-hour recalls, and by measuring NO3- intake biomarkers. Feasibility was assessed by obtaining qualitative feedback and evaluating trial recruitment, retention, compliance with study visits and measurement protocols. Results: Participant recruitment started in July 2018 and ended in April 2019. Of all the recruitment strategies that were used, advertisement of the study via Facebook generated the highest response rate. Sixty-two participants consented and were enrolled. Overall, characteristics of included participants matched our recruitment criteria.Conclusion: The findings from this study provide evidence of the acceptability and feasibility of an intervention investigating the effects of incremental doses of high-nitrate BJ over a prolonged period. Trial registration: The intervention study was registered with clinical trial ISRCTN registry (ISRCTN14746723) on 27 December 2018.

Publication metadata

Author(s): Babateen AM, Rubele S, Shannon O, Okello E, Smith E, McMahon N, O'Brien G, Wightman E, Kennedy D, Mathers JC, Siervo M

Publication type: Article

Publication status: Published

Journal: Contemporary Clinical Trials Communications

Year: 2020

Volume: 18

Print publication date: 01/06/2020

Online publication date: 25/04/2020

Acceptance date: 19/04/2020

Date deposited: 24/04/2020

ISSN (electronic): 2451-8654

Publisher: Elsevier Inc.


DOI: 10.1016/j.conctc.2020.100571


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