Vitamin C good for blood pressure: Meta-analysis

Vitamin C supplementation was associated with significant reductions in systolic and diastolic blood pressure of 3.84 and 1.48 mm Hg, according to findings published in the American Journal of Clinical Nutrition​.

In addition, when the data was limited to people with high blood pressure (hypertension), supplements of vitamin C were associated with systolic and diastolic blood pressure reductions of 4.85 and 1.67 mm Hg, report researchers from Johns Hopkins Medical Institution.

The meta-analysis is said to be the first to evaluate the effects of vitamin C on blood pressure. Despite such promising results, the authors noted that there was a lot of variation in the studies included in their analysis, and that the data available was primarily from small, short-term trials.

“Before vitamin C supplementation can be recommended for the prevention of hypertension or as adjuvant antihypertensive therapy, additional trials are needed, designed with large sample sizes, and with attention to quality of blood pressure assessment.”​

One death every 39 seconds​

About one billion people worldwide suffer from high blood pressure (hypertension), defined as having a systolic and diastolic blood pressure (BP) greater than 140 and 90 mmHg.

According to the most recent data from the American Heart Association​, about 33.5% of US adults have hypertension, a leading cause of cardiovascular disease. CVD accounted for about 35% of annual deaths in the US, with somebody in the US dying from CVD every 39 seconds.

Vitamin C​

The new meta-analysis offers potential hope that vitamin C may reduce the risk of hypertension. The Johns Hopkins researchers pooled data from 29 clinical trials, with the median dose of vitamin C calculated to be 500 milligrams per day, and a median trial duration of eight weeks.

Results showed that vitamin C supplementation was associated with a significant reduction in both systolic and diastolic blood pressure, with greater reductions observed in people with hypertension.

“Although our meta-analysis reported significant BP-lowering effects with vitamin C supplementation, several long-term trials powered for clinical endpoints have not shown benefit,”​ wrote the researchers.

“Long-term trials with clinical endpoints are difficult and costly but are still needed to determine whether vitamin C supplementation reduces the risk of cardiovascular events.”​

Source: American Journal of Clinical Nutrition​
Published online ahead of print, doi: 10.3945/ajcn.111.027995
“Effects of vitamin C supplementation on blood pressure: a meta-analysis of randomized controlled trials”​
Authors: S.P. Juraschek, E. Guallar, L.J. Appel, E.R. Miller III