Effects of a 'healthy' diet and of acute and long-term vitamin C on vascular function in healthy older subjects

• Published in: Cardiovascular research Vol. 56; no. 1; pp. 118 - 125
• Main Author: Singh, N
• Format: Journal Article
• Language: English
• Published: Oxford Oxford University Press 01.10.2002
• Subjects: Administration, Oral; Aged; Aged, 80 and over; Aging - physiology; Area Under Curve; Ascorbic Acid - administration & dosage; Ascorbic Acid - blood; Biological and medical sciences; Bradykinin; Cardiovascular system; Diet, Mediterranean; Dose-Response Relationship, Drug; Endothelium, Vascular - drug effects; Endothelium, Vascular - physiology; Female; Forearm - blood supply; Humans; Injections, Intra-Arterial; Investigative techniques of hemodynamics; Investigative techniques, diagnostic techniques (general aspects); Male; Medical sciences; Middle Aged; Muscle, Smooth, Vascular - drug effects; Muscle, Smooth, Vascular - physiology; Nitric Oxide Donors; Nitroglycerin; Plethysmography; Regional Blood Flow - drug effects; Regional Blood Flow - physiology; Statistics, Nonparametric; Vasodilator Agents; Human; Ascorbic acid; Acute; Exploration; Long term; Endothelium; Vasomotricity; Diet; Hemodynamics; Supplementation; Vascular wall; Elderly; Comparative study
• ISSN: 0008-6363
• DOI: 10.1016/S0008-6363(02)00514-X

Aging is associated with endothelial dysfunction. We studied the acute and longer-term effects of vitamin C compared to a 'Mediterranean-type' diet on endothelial function in healthy older subjects. Bilateral venous occlusion plethysmography was used to measure forearm blood flow in subjects aged 57-80 years. Responses to cumulative intra-arterial doses of the endothelium-dependent dilator bradykinin (BK; n=56; 20, 40, 80 pmol/min) and the nitric oxide donor glyceryl trinitrate (GTN; n=54; 4, 8, 16 nmol/min), were determined alone and in the presence of vitamin C (25 mg/min). We then randomised 54 subjects to a 'healthy' diet (n=18), vitamin C (1 g/day; n=18) or placebo for 6 weeks and reassessed endothelial and smooth muscle function. Acute intra-arterial vitamin C did not alter dilatation to BK or GTN. Similar increases in plasma vitamin C occurred on oral vitamin C (83+/-4 to 135+/-8 micromol/l) and 'healthy' diet (84+/-5 to 135+/-27 micromol/l; P<0.01 for both), with no change seen on placebo. Treatment with a 'healthy' diet but not oral vitamin C improved endothelium-dependent (P=0.043) and endothelium-independent dilatation (P=0.011). A 'Mediterranean-type' diet rich in vitamin C improves vascular function. Neither acute intra-arterial nor sustained administration of oral vitamin C improves vascular function in healthy older subjects.