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Effects of inorganic nitrate and vitamin C co-supplementation on blood pressure and vascular function in younger and older healthy adults: a randomised double-blind crossover trial

Lookup NU author(s): Ammar Ashor, Dr Oliver Shannon, Anke Werner, Dr Filippo Scialo, Emeritus Professor Chris Seal, Professor John Mathers, Dr Mario Siervo

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Abstract

© 2019 Elsevier Ltd and European Society for Clinical Nutrition and Metabolism Background: Vitamin C and inorganic nitrate have been linked to enhanced nitric oxide (NO) production and reduced oxidative stress. Vitamin C may also enhance the conversion of nitrite into NO. Aims: We investigated the potential acute effects of vitamin C and inorganic nitrate co-supplementation on blood pressure (BP) and peripheral vascular function. The secondary aim was to investigate whether age modified the effects of vitamin C and inorganic nitrate on these vascular outcomes. Methods: Ten younger (age 18–40 y) and ten older (age 55–70 y) healthy participants were enrolled in a randomised double-blind crossover clinical trial. Participants ingested a solution of potassium nitrate (7 mg/kg body weight) and/or vitamin C (20 mg/kg body weight) or their placebos. Acute changes in resting BP and vascular function (post-occlusion reactive hyperemia [PORH], peripheral pulse wave velocity [PWV]) were monitored over a 3-h period. Results: Vitamin C supplementation reduced PWV significantly (vitamin C: −0.70 ± 0.31 m/s; vitamin C placebo: +0.43 ± 0.30 m/s; P = 0.007). There were significant interactions between age and vitamin C for systolic, diastolic, and mean arterial BP (P = 0.02, P = 0.03, P = 0.02, respectively), with systolic, diastolic and mean BP decreasing in older participants and diastolic BP increasing in younger participants following vitamin C administration. Nitrate supplementation did not influence BP (systolic: P = 0.81; diastolic: P = 0.24; mean BP: P = 0.87) or vascular function (PORH: P = 0.05; PWV: P = 0.44) significantly in both younger and older participants. However, combined supplementation with nitrate and vitamin C reduced mean arterial BP (−2.6 mmHg, P = 0.03) and decreased PWV in older participants (PWV: −2.0 m/s, P = 0.02). Conclusions: The co-administration of a single dose of inorganic nitrate and vitamin C lowered diastolic BP and improved PVW in older participants. Vitamin C supplementation improved PWV in both age groups but decreased systolic and mean BP in older participants only. Clinical trial registration: Current Controlled Trials (ISRCTN98942199).


Publication metadata

Author(s): Ashor AW, Shannon OM, Werner A-D, Scialo F, Gilliard CN, Cassel KS, Seal CJ, Zheng D, Mathers JC, Siervo M

Publication type: Article

Publication status: Published

Journal: Clinical Nutrition

Year: 2020

Volume: 39

Issue: 3

Pages: 708-717

Print publication date: 01/03/2020

Online publication date: 20/03/2019

Acceptance date: 09/03/2019

Date deposited: 07/06/2019

ISSN (print): 0261-5614

ISSN (electronic): 1532-1983

Publisher: Elsevier

URL: https://doi.org/10.1016/j.clnu.2019.03.006

DOI: 10.1016/j.clnu.2019.03.006


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