Vitamin C could lower BP

HIGH-dose vitamin C significantly reduces blood pressure, according to findings from a meta-analysis of short-term trials.

Pooled analysis of 29 studies in which participants took a median 500mg/d vitamin C supplement found systolic BP reduced by an average of 3.84mmHg and diastolic BP by 1.48mmHg.

The trials included in the systematic review involved healthy adults or patients with cardiovascular risk factors including hypertension or diabetes and BP outcomes assessed across a median eight weeks.

“Our meta-analysis suggests that vitamin C supplementation may have a useful role in lowering BP,” the authors wrote.

However they cautioned that before supplementation could be recommended as therapy or for prophylaxis, additional larger and longer-running studies were needed.

The authors, from John Hopkins School of Medicine, Baltimore, and Spain’s National Center for Cardiovascular Research, said three longer term trials, which they excluded from the present analysis, also provided evidence of BP lowering with vitamin C.

These studies were excluded because the findings may have been muddied as they included permission for anti-hypertensive medication to be used.

Biological plausibility for the effect of vitamin C on BP had been established in studies showing ascorbic acid improved nitric oxide bioactivity and improved endothelial function of coronary arteries, they said.

American Journal of Clinical Nutrition 2012; online 4 April