Sunday June 29, 2014 (foodconsumer.org) -- Newcastle University researchers conducted a meta-analysis of previous trials and confirm that vitamin C intake or supplementation can help prevent endothelial dysfunction, which would lead to cardiovascular disease, and the beneficial effect varies by the health status of an individual.

Observational studies show that higher vitamin C intake is correlated with reduced risk of cardiovascular disease, but randomized controlled trials on the effect of vitamin C on endothelial function yielded different conclusions.

For the study, researchers sorted out 44 clinical trials from the major databases including Medline, Embase, Cochrane Library, and Scopus databases and analyzed pooled data from the studies.

An analysis of the pooled data showed that vitamin C has a significant positive effect on endothelial function.  The particularly significant improvement in endothelial function was found in patients at high risk for vascular diseases including atheroslcerotic, diabetic and heart failure patients.

The effect size was found unaffected by trial design, duration, baseline serum vitamin C level or the route of administration of vitamin C.  However, the dose of vitamin C was associated positively with the improvement in endothelial function, that is, high vitamin C dose was linked to better endothelial function.

The review concluded "Vitamin C supplementation improved EF (endothelial function). The effect of vitamin C supplementation appeared to be dependent on health status, with stronger effects in those at higher cardiovascular disease risk."

Endothelial dysfunction can result from and contribute to the development of diseases like diabetes mellitus, hypertension, high cholesterol, septic shock, Behcet's disease.  Environmental risk factors such as smoking can also impair endothelial function leading to cardiovascular disease.

Vitamin C (other antioxidants may also be possible), potassium, and L-arginine supplementation can help prevent endothelial dysfunction.  Additionally, exercise, smoke cessation, weight loss and avoidance of trans fat can improve endothelial function. (david Liu, PHD)

Ashor AW, Lara J, Mathers JC, Siervo M.  Effect of vitamin C on endothelial function in health and disease: A systematic review and meta-analysis of randomised controlled trials.  Atherosclerosis. 2014 Jul;235(1):9-20. doi: 10.1016/j.atherosclerosis.2014.04.004. Epub 2014 Apr 18.