The results of a meta-analysis described online on November 27, 2013 in the Journal of the American Heart Association reveal a protective effect for having a high vitamin C level or consuming more of the vitamin against the risk of stroke.
Pooled analysis of participants in studies of plasma or serum vitamin C revealed a 38% lower risk of stroke for subjects with high versus low levels.
Researchers selected twelve prospective studies involving vitamin C intake and six that examined serum or plasma vitamin C levels for their analysis. Studies of dietary vitamin C included a total of 217,454 men and women, in whom 3,762 strokes occurred over durations of 6.1 to 30 years. Among the 29,648 participants in the studies involving circulating vitamin C, there were 989 cases of stroke over follow-up periods ranging from 9.5 to 20 years.
They suggest greater vitamin C consumption for populations with low intake or who are at high risk of stroke and suggest that, since established risk factors appear to be responsible for only half of the cases of stroke that occur, vitamin C levels could serve as an additional predictor of risk.
“Vitamin C is a strong antioxidant, and has been shown to reduce the oxidation of low-density lipoproteins, to inhibit the proliferation of smooth muscle, to protect membrane from peroxidation, and ultimately to slow the progression of atherosclerosis,” the authors write. “There is also growing evidence that systemic inflammation is involved in stroke etiology and pathology, and plasma or dietary vitamin C has been suggested to have antiinflammatory properties. Vitamin C intake in plasma has also been demonstrated to be inversely associated with blood pressure.”