Is vitamin C an effective antihypertensive supplement? A review and analysis of the literature

Abstract

Objective Hypertension is a common condition with high mortality from associated diseases. Epidemiological evidence suggests that a dietary deficiency of vitamin C may be a risk factor for hypertension. However the literature on vitamin C interventional trials appears divided on the efficacy of vitamin C utilization clinically. Methods A literature search and review of published trials using vitamin C in treating patients with hypertension was undertaken. Relevant references were located using MEDLINE (1966–2005) and the bibliographies of located articles. Results Thirteen trials making up 14 separate groups were identified and analyzed providing a pooled population of 284 hypertensive patients (52% female), with a weighted mean age of 58.8 ± 9.5 years. Median vitamin C dose and study intervention duration was 500mg/day and 6 weeks respectively. The weighted mean baseline and post treatment systolic blood pressures across all 14 groups were 149.6 ± 11.1 and 145.7 ± 11.0 mmHg respectively. This represented a systolic blood pressure decrease of 3.9 mmHg. Seven of the 14 groups ascertained statistically significant reductions (p < .05) in systolic blood pressures. However only 2 of the 14 groups found significant reductions in diastolic blood pressure. The weighted mean baseline and post treatment diastolic blood pressures across all 14 groups were 84.6 ± 4.4 and 82.5 ± 4.1 mmHg respectively. This represented a diastolic blood pressure decrease of 2.1 mmHg. Conclusion Vitamin C supplementation in hypertensive patients appears to possess modest effects on reducing systolic blood and diastolic blood pressure.