Friday, September 10, 2010

Antioxidants Essential to Cardiac Health

Effect of Long-term Treatment with Antioxidants (Vitamin C, Vitamin E, Coenzyme Q10 and Selenium) on Arterial Compliance, Humoral Factors and Inflammatory Markers in Patients with Multiple Cardiovascular Risk Factors Nutrition and Metabolism, September 2010

Oxidative stress has been considered as a potential pathogenic mechanism for initiation and progression of atherosclerotic disease. Excessive production of reactive oxygen species, a mediator of the oxidative stress cascade, leads to release of inflammatory cytokines, oxidation of LDL and prothrombotic state, and finally results in endothelial dysfunction and atherosclerotic vascular lesions. Adequate dietary, enzymatic and nonenzymatic antioxidant supplementation may be effective in lowering oxidative stress. Although most trials with antioxidants in experimental models of atherosclerosis have demonstrated that this treatment is able to retard the progression of atherosclerosis, the results of clinical trials are equivocal. Differences in the definition criteria of patients who are potential candidates for antioxidant treatment, type and dosage of antioxidant supplementation, as well as outcome measures may explain this variability. Since oxidative stress is activated by many cardiovascular risks factors such as hypertension, hyperglycemia, dyslipidemia and smoking, patients with multiple cardiovascular risk factors could obtain beneficial effect from antioxidant treatment. Additionally, combinations of dietary antioxidants (vitamin C and vitamin E) with carrier in mitochondrial oxidative phosphorylation (coenzyme Q10) and trace elements essential for adequate function of many antioxidant enzymes (selenium) may underlie the synergism between them and amplify the positive antioxidant effect.

The present study was designed to determine the effect of antioxidant supplementation with vitamin C, vitamin E, coenzyme Q10 and selenium on arterial compliance, inflammatory and metabolic parameters in patients with multiple cardiovascular risk factors.

In a randomized, placebo-controlled study 70 patients with at least two cardiovascular risk factors were recruited for study participation. Participants were randomly assigned to two groups. Group 1 received oral antioxidant supplementation with 2 capsules per day. Each capsule contained vitamin C (500 mg) vitamin E (200 iu), co-enzyme Q10 (60 mg) and selenium (100 mcg), Group 2 received matching placebo for 6 months.

The present randomized, placebo controlled study demonstrated that antioxidant supplementation significantly increased large and small artery elasticity in patients with multiple cardiovascular risk factors. This beneficial vascular effect was associated with an improvement in glucose and lipid metabolism as well as significant decrease in blood pressure. No major prospective study associating arterial elasticity with cardiovascular events has ever been performed.

The findings of the present study concur with those of previous studies that have shown substantial reduction in blood pressure and improvement in long-term glycemic control with oral CoQ supplementation, reduction in plasma glucose and insulin resistance with high doses of vitamin E supplementation and significant reduction in blood pressure levels with vitamin E as well as vitamin C in hypertensive patients.

The study has several limitations. First, the present study contains relatively small number of participants and larger studies are required to establish the beneficial vascular effect of antioxidant supplementation. Second, the researchers did not measure plasma levels of the antioxidants which would have added the information regarding treatment compliance and would have elucidated the pathophysiology for vascular action of antioxidants. Furthermore, since the present study has focused on patients with multiple cardiovascular risk factors, the application of our findings to other patient populations remains uncertain.

What the researchers did demonstrate is that combined antioxidant supplementation with vitamin C, vitamin E, coenzyme Q10 and selenium has beneficial effect on glucose and lipid metabolism, blood pressure and arterial compliance in patients with multiple cardiovascular risk factors. The findings of the present study justify investigating the overall clinical impact of antioxidant treatment in this population.

Bonnie - while a small sample size, the study was extremely well-controlled and one of the first to show major improvement in those with cardiovascular risk factors.

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