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RESEARCH PRODUCT

Is At Least One Vitamin Helping Our Vasculature?

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See related article, pp 1290–1298 Cardiovascular risk factors such as diabetes mellitus, arterial hypertension, chronic smoking, and hypercholesterolemia are cardiovascular risk factors known to be associated with endothelial dysfunction, a condition that may predict long-term progression of atherosclerosis as well as cardiovascular event rates (for review, see Munzel et al1) Although the mechanisms underlying this phenomenon are complex and multifactorial, there is growing body of evidence that oxidative stress attributable to increased production of reactive oxygen–derived free radicals may play a pivotal role in this process.2 Increased superoxide production by enzyme systems such as the nicotinamide adenine dinucleotide phosphate oxidase may then cause oxidative modification of the protective endothelial NO synthase. This phenomenon termed eNOS uncoupling switches the enzyme from a antiatherosclerotic NO producing to a pro-oxidative, superoxide-producing enzyme.3 Although the concept of increased oxidative stress burden in cardiovascular disease is in general accepted, the results of trials with antioxidants such as vitamin B, C, and E and with folic acid in combination with B vitamins are in general disappointing, and in some aspects, vitamins are accused even to precipitate cardiovascular events.2 For example, in a meta-analysis, vitamin E treatment has been shown to increase mortality,4 and the Heart Outcomes Prevention Evaluation (HOPE)5 and HOPE The Ongoing Outcome (TOO)6 trials revealed that vitamin E more often …