A DOUBLE-BLIND, PLACEBO-CONTROLLED PARALLEL TRIAL OF VITAMIN-C TREATMENT IN ELDERLY PATIENTS WITH HYPERTENSION

We have investigated the effect on blood pressure of treatment with vi tamin C (an antioxidant and free radical scavenger) in patients with b oth systolic and essential hypertension. Following a 2-week run-in pha se, two age- and sex-matched groups of untreated hypertensive subjects were randomised in a double-blind study to receive 6 weeks' oral trea tment with either vitamin C, 250 mg twice daily (n = 22; 8M/14F, mean age 73.7 +/- 4.9 years) or placebo, one capsule twice daily (n = 26; 1 0M/16F, mean age 73.8 +/- 5.3 years). Blood pressure was measured in t he sitting position using a random zero sphygmomanometer on three occa sions during the run-in phase, and again at 2, 4 and 6 weeks after com mencing treatment. Venous blood samples for measurement of plasma asco rbic acid (AA) and lipid peroxides (LP) were measured in all subjects at baseline and at 4 and 6 weeks after the start of vitamin C or place bo treatment. During the study period, significant falls in both systo lic (vitamin C group, mean change -10.3 (95% CI 0.7-20.0) mm Hg, p = 0 .05) and diastolic (vitamin C group, mean change -5.9 (95% CI 0.2-11.5 ) mm Hg, p = 0.03; placebo group, mean change -4.7 (95% CI 0.3-9.1) mm Hg, p = 0.05) blood pressure occurred. However, no statistical differ ence between the effects of either treatment on blood pressure was obs erved. At baseline, AA concentrations were lower in the vitamin C-trea ted group compared with the placebo group (44.6 +/- 2.4 vs. 57.7 +/- 4 .2 mu mol/l, p < 0.05). At 6 weeks, AA concentrations were similar to baseline in the placebo group (50.8 +/- 4.6 mu mol/l) but were signifi cantly higher than at baseline in the vitamin C-treated group (80.7 +/ - 7.5 mu mol/l, p < 0.001). At baseline, LP concentrations were simila r in the vitamin C and placebo-treated groups (5.0 +/- 1.0 vs. 3.6 +/- 0.8 nmol/l, respectively). After 6 weeks' treatment with vitamin C, L P concentrations fell significantly to 1.6 +/- 0.4 nmol/l, but no sign ificant change after placebo was observed (4.4 +/- nmol/l). We conclud e: (1) No significant fall in blood pressure occurred after 6 weeks' t reatment with vitamin C in comparison with placebo; (2) vitamin C trea tment is associated with a marked antioxidant action but further studi es are required to relate whether this action is relevant to any hypot ensive action of this vitamin; (3) the small fall in systolic blood pr essure after vitamin C may have wider implications in population-based studies in reducing stroke incidence in elderly patients and suggests the need for large long-term studies to be established.