Study Shows Vitamin C Lowers Blood Pressure
Dec. 10, 1999 (Indianapolis) -- Studies have shown that increased dietary intake of vitamin C is related to lower blood pressure (BP) readings. A new study in the Dec. 11 issue of the journal The Lancet shows similar results.
"We are interested in the effects of vitamin C on coronary heart disease," says author Joseph A. Vita, MD, who is associate professor of medicine at the Boston University School of Medicine, in an interview with WebMD. "We published another study earlier this year that observed some beneficial effects, including dilation of the blood vessels, in people taking vitamin C. We were also intrigued by the literature that suggests the amount of vitamin C in the diet actually influences blood pressure, with the more vitamin consumed, the lower the blood pressure."
Forty-five otherwise healthy patients with a history of high blood pressure were enrolled in the study. Following a 2 g dose of vitamin C on the first visit, they were given either placebo or 500 mg a day of vitamin C. Medications to treat high BP were withheld for either 12 or 24 hours prior to two visits, one month apart. Otherwise, regular medications were continued through the time period. Patients were told to fast overnight and not smoke for 24 hours prior to the visits.
Systolic BPs (the higher number) in the two groups were similar in the beginning and at two hours after the initial dose. Following one month of vitamin C use, average systolic pressure had fallen for the subjects who were taking the vitamin C, whereas the placebo had no effect. Vitamin C concentrations in the blood were similar at the beginning of the study between the two groups and increased in the vitamin C group at both two hours and one month. There was an inverse correlation between the change in average BP and the change in vitamin C concentrations. This means that as the amount of vitamin C in the blood goes up, the person's BP goes down.
"Vitamin C is a safe medicine with almost no known side effects," says Vita. "This is potentially a new treatment that people with high blood pressure might add under the direction of their doctor. Since we do yet know if this effect can be sustained for periods longer than 30 days, I certainly would not want any patients to stop taking their blood pressure medicines based on this report."