Ammar W Ashor1, Oliver M Shannon2, Anke-Dorothee Werner2, Filippo Scialo3, Cameron N Gilliard4, Katelyn S Cassel5, Chris J Seal6, Dingchang Zheng7, John C Mathers2, Mario Siervo8. 1. Department of Internal Medicine, College of Medicine, Mustansiriyah University, Baghdad, Iraq; Human Nutrition Research Centre, Institute of Cellular Medicine, Newcastle University, William Leech Building, Framlington Place, Newcastle upon Tyne, NE2 4HH, United Kingdom. Electronic address: a.w.a@uomustansiriyah.edu.iq. 2. Human Nutrition Research Centre, Institute of Cellular Medicine, Newcastle University, William Leech Building, Framlington Place, Newcastle upon Tyne, NE2 4HH, United Kingdom. 3. Institute for Cell and Molecular Biosciences, Campus for Ageing and Vitality, University of Newcastle, Newcastle upon Tyne, NE4 5PL, United Kingdom. 4. Department of Anesthesiology, Penn State Health Milton S. Hershey Medical Center, 500 University Drive, Hershey, PA, 17033, USA. 5. Molecular Medicine Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, United States. 6. Department of Internal Medicine, College of Medicine, Mustansiriyah University, Baghdad, Iraq. 7. Faculty of Medical Science, Anglia Ruskin University, Bishop Road, Chelmsford, CM1 1SQ, United Kingdom. 8. Human Nutrition Research Centre, Institute of Cellular Medicine, Newcastle University, William Leech Building, Framlington Place, Newcastle upon Tyne, NE2 4HH, United Kingdom; School of Life Sciences, The University of Nottingham Medical School, Queen's Medical Centre, Nottingham, NG7 2UH, UK.
Abstract
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).
RCT Entities:
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).
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