Vitamin C benefits article

No clinical trials on the primary prevention of heart disease by vitamin C have yet been published. Instead, trials have investigated secondary prevention—the prevention of plaque progression, heart attacks, strokes, and/or mortality in people who already have heart disease. An abstract of one controversial study in 573 people, part of the Los Angeles Atherosclerosis Study in 2000, claimed that supplemental—but not dietary—vitamin C was associated with thickening of the carotid arterial wall. In contrast, an earlier study in Circulation of over 11,000 people reported that supplemental vitamin C in men and women and supplemental vitamin E in women were associated with reduced carotid artery wall thickness. Evidence on the primary prevention of heart disease by vitamin C is limited to epidemiological studies, which correlate dietary factors with disease risk. A meta-analysis of nine such studies with a total of about 293,000 subjects followed for 10 years was published in the American Journal of Clinical Nutrition in 2004. At baseline, the subjects were older than 35 years and did not have heart disease. Intake of dietary and supplemental antioxidants was estimated from questionnaires, which may not truly assess actual dietary intake and supplement use over time. Although the investigators found that vitamin E did not reduce the risk for heart disease, they did find that the intake of more than 700 mg/day of supplemental vitamin C significantly reduced the risk of heart disease by about 25%. Dietary vitamin C had little effect on heart disease risk. The report noted that these results are aligned with previous studies that found a protective effect for an intake of vitamin C greater than 500 mg/day. The biochemical mechanism responsible for vitamin C’s salubrious effects remains uncertain, but may be related to its ability to lower blood pressure, its function as an antioxidant to help attenuate oxidative stress, or its ability to relax arteries, resulting in better blood flow.

• The verdict: The majority of studies that investigated the role of vitamin C in heart disease have reported beneficial effects. This new meta-analysis offers further confirmation that supplemental vitamin C lowers the risk of heart disease. -link

A nice article reviewing recent studies on vitamin C and E.