Blood Pressure and Antioxidants
Essential hypertension, which is high blood pressure that develops without apparent cause, may be due to oxidative stress. Oxidative stress is a situation where chemical “bullets” (actually electrons) cause damage to the body. Antioxidant nutrients, like vitamin C act as chemical “bullet proof 
vests”. Vitamin C protects against oxidative stress. Researchers at Boston University School of Medicine and the Linus Pauling Institute at Oregon that vitamin C supplementation can lower blood pressure, possibly because of this antioxidant activity. This was published in the Lancet (Volume 354, Number 9195; 11 December 1999). The dose utilized in the study was 500 mg/day. It was a small double-blind, placebo-controlled study, involving 45 patients; all with diastolic blood pressure higher than 90 mm. Hg. Patients who were medicated discontinued their medication before the study, avoiding the influence of the medications.
The mean blood pressure, diastolic pressure and systolic pressure decreased an average of 9% one month after the vitamin C supplementation began. On average systolic pressure dropped from 155 to 142; diastolic from 87 to 79; and mean blood pressure from 110 to 100 mm Hg.
One possible explanation is that vitamin C is an antioxidant and may act to protect blood vessels and make them more pliable. Of course this was a very small study, but it is encouraging enough to be worth further investigation.
