SHAFA HOSPITAL, KERMAN UNIVERSITY OF MEDICAL SCIENCE, KERMAN IRAN
Objective: An evaluation of the effect of vitamin C on blood pressure is very important because hypertension is a major risk factor for cardiovascular, cerebral and renal diseases.
We studied the effect of vitamin C on the blood pressure of patients between 35-50 years old with mild primary hypertension in Kerman.
Methods: We conducted a prospective one-year double-blind, placebo controlled parallel trial on 42 middle aged patients with mild primary hypertension at the hypertension clinic in Kerman University of Medical Sciences. Following a 2-week run-in phase, two age and sex matched groups of untreated hypertensive subjects received 8 weeks oral treatment with either vitamin C, 250 mg twice daily (n=21; 8 M/13F, mean age 42.7±5.3 years) or placebo one tablet twice daily (n=21; 10 M/IIF, mean age 42.7± 5.9 years). Blood pressure was measured in the sitting position on three occasions during the run-in phase, and again at 1, 2, 4 and 8 weeks after commencing treatment. Venous blood samples for the measurement of plasma ascorbic acid were measured at baseline and at 1, 2, 4, 8 weeks after treatment.
Results: Plasma ascorbic acid level in vitamin C group significantly changed from 8.8±3 umol/l at baseline to 32.3±12 umolll at 8 weeks, but in placebo-treated group, it changed from 13.8±6 umolll at baseline to 9.01±4.1 umolll at 8 weeks during the study period.
A more significant fall in mean blood pressure was observed in the vitamin C group than the placebo-treated group such that the mean systolic blood pressure decreased from 153.1± 5 to 144±5.3 mmHg in vitamin C group and from 154.1±4.9 to 149±4.9mmHg in the placebo group. The mean diastolic blood pressure decreased from 95.711.4 to 91.4±1.7 mmHg in the vitamin C group and from 96.2±1.6 to 94.0±1.6 mmHg in the other group.
At 8 weeks, the significant difference in the reduction of systolic blood pressure (p<0.05) and diastolic blood pressure (p<0.001) between the two groups became apparent.
Conclusion: Vitamin C intake has a useful effect on lowering blood pressure.