However, there is no scientific evidence to support this concept. Many epidemiological studies and some clinical trials have suggested that dietary intake or supplementation of vitamin C is associated with a reduced risk of heart disease and stroke. Although this study indicated that vitamin C supplements provide cardiovascular benefits above and beyond the vitamin C obtained from the diet, two other large epidemiological studies published in 1996 found no effect on heart disease risk in people who take regular vitamin C supplements. Importantly, not a single epidemiological study or clinical trial has found an increased risk of heart attacks or strokes in people taking vitamin C supplements. Over twenty clinical studies since 1996, published primarily in Circulation, have consistently found beneficial effects of vitamin C administered either orally or by intra-arterial infusion on the relaxation of arteries, or vasodilation.
Impaired vasodilation is an important risk factor for angina, heart attacks, and strokes.
Vasodilation in patients with heart disease is significantly improved following daily supplementation with 500 mg of vitamin C for thirty days and is comparable to vasodilation seen in healthy people. Beneficial effects of vitamin C supplements leading to normalization of vasodilation have also been observed in patients with angina, heart failure, high cholesterol levels, hypertension, diabetes, high homocysteine levels, and in smokers. Additionally, a recent study in Lancet demonstrated that 500 mg of vitamin C given daily for thirty days lowers blood pressure in patients with mild to moderate hypertension. High blood pressure is a major risk factor for heart disease and strokes. The salubrious effects of vitamin C were comparable to those derived from conventional anti-hypertensive medications.