High Blood Pressure
Effect of vitamin C on ambulatory blood pressure and plasma lipids in
older persons.
Fotherby MD; Williams JC; Forster LA; Craner P; Ferns GA
J Hypertens 2000 Apr;18(4):411-5
OBJECTIVES: To determine the effect of oral vitamin C supplements on
ambulatory blood pressure and plasma lipids. DESIGN: A 6-month double-blind
randomized placebo-controlled cross-over study with a 1 -week washout
between cross-over periods. METHODS: Vitamin C 500 mg daily or matching
placebo was given to 40 men and women aged between 60 and 80 years for
3 months each in a cross-over fashion. Clinic and 24-h ambulatory blood
pressure, plasma ascorbate and lipids were measured at baseline and at
the end of each cross-over phase. RESULTS: Clinic blood pressure did not
change between placebo and vitamin C phases. Daytime ambulatory blood
pressure showed a small but significant fall in systolic blood pressure
(2.0 +/- 5.2 mmHg; 95% confidence interval 0-3.9 mmHg) but not in diastolic
blood pressure. Regression analysis showed that with increasing baseline
daytime blood pressure the fall in blood pressure with vitamin C supplementation
increased. Regression analysis of the change in high-density lipoprotein
(HDL) cholesterol showed a significant effect of sex on the change in
HDL cholesterol. In women, but not men, HDL cholesterol increased significantly
by 0.08 +/- 0.11 mmol/l, P=0.007. There was no change in low-density lipoprotein
cholesterol between treatment periods. CONCLUSION: In older adults high
intakes of ascorbic acid have modest effects on lowering high systolic
blood pressure, which could contribute to the reported association between
higher vitamin C intake and lower risk of cardiovascular disease and stroke. |