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

Ashor, Ammar W.; Shannon, Oliver M.; Werner, Anke-Dorothee; Scialo, Filippo; Gilliard, Cameron N.; Cassel, Katelyn S.; Seal, Chris J.; Zheng, Dingchang; Mathers, John C.; Siervo, Mario

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).

Citation

Ashor, A. W., Shannon, O. M., Werner, A., Scialo, F., Gilliard, C. N., Cassel, K. S., …Siervo, M. (2019). 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. Clinical Nutrition, https://doi.org/10.1016/j.clnu.2019.03.006

• Journal Article Type: Article
• Acceptance Date: Mar 9, 2019
• Online Publication Date: Mar 20, 2019
• Publication Date: Mar 20, 2019
• Deposit Date: Nov 20, 2019
• Journal: Clinical Nutrition
• Print ISSN: 0261-5614
• Electronic ISSN: 1532-1983
• Publisher: Elsevier
• Peer Reviewed: Peer Reviewed
• DOI: https://doi.org/10.1016/j.clnu.2019.03.006
• Keywords: Nutrition and Dietetics; Critical Care and Intensive Care Medicine
• Public URL: https://nottingham-repository.worktribe.com/output/3344417
• Publisher URL: https://www.sciencedirect.com/science/article/pii/S0261561419301190?via%3Dihub#!
• Additional Information: REF_eligibility comment: Output can be accessed via a non-UoN repository, in accordance with REF OA requirements – please see https://eprints.ncl.ac.uk/256456. Deposited in Newcastle University repository on 07/06/2019 i.e. within 3 months of acceptance.