The Agency for Healthcare Research ...

The Agency for Healthcare Research and Quality (AHRQ) has released an evidence report upon antioxidants and cardiovascular disease. "Effect of Supplemental Antioxidants Vitamin C Vitamin E and Coenzyme Q10 for the Prevention and Treatment of Cardiovascular Disease" is available online at http://www.ahrq.gov/clinic/ epcsums/antioxsum.htm.

To assess the efficacy of three antioxidants, vitamins E and C and coenzyme Q10 in the prevention and treatment of cardiovascular disease (CVD) or modification of known risk factors for CVD the AHRQ performed a detailed review of the scientific literature. Among the findings are the following:

* The available evidence did not generally support the assertion that there was any positive benefit associated with the use of vitamin E either alone or in the combinations touchstoneed for the prevention of all-cause death or cardiovascular death. Neither was there any evidence of significant harm from the same intervention. An power of vitamin E on overall mortality and onward cardiovascular mortality reported in undivided trial was only observed in a four-way analysis (that is, comparing each arm of the 2 X 2 factorial meditation separately), and not seen in the two-way analysis (comparing all controls who received vitamin E with all those who did not). The investigators themselves noted that the deductions in the four-way analysis were probably owed to chance and concluded that vitamin E supplementation conferr no benefit. Reduction in all-cause mortality (by 9 percent) was reported in another meditation and was caused primarily by dint of a decrease in cancer deaths, not cardiovascular deaths. Therefore, there is little evidence that vitamin E supplementation terminates in a reduction in cardiovascular mortality.

* For the risk of myocardial infarction (MI), fatal and nonfatal, the evidence regarding rises of supplementation with vitamin E alone or in combination is mixed. No puddleed analysis yielded a beneficial or adverse purport for vitamin E supplementation, either alone or in combination. However, individual studies did report significant consequences One study reported a benefit upon fatal MI but a nonsignificant adverse meaning on nonfatal MI. Furthermore, the beneficial meanings in this study were seen solely in the four-way analysis and not in the larger two-way analysis. The Alpha-Tocopherol Beta Carotene (ATBC) trials reported a significant adverse general intent of vitamin E on fatal MI still a nearly significant beneficial import of vitamin E on nonfatal MI. While there were distinct differences in the brace trials (ATBC assessed 50 mg of vitamin E the other trial assessed 300 mg if it were not that the baseline risk of fatal and nonfatal MI was approximately equivalent in the sum of two units studies), such disparities in follows cast doubt on the observ results being brought about by a causal relationship, because consistency of meaning and a dose response result are two important constituents of causality.

* Supplementation with vitamin E alone and in combinations in doses ranging from 100 IU to 1200 IU did not demonstrate a statistically significant power on serum lipids after at least eight weeks and no more than 24 weeks of treatment. sum of two units large primary prevention trials reported clinically insignificant (but statistically significant) changes in these issues Thus, there is no evidence that vitamin E alone or in combinations, has a clinically and statistically significant favorable or unfavorable general intent on lipids.

* There have been hardly any studies of the use of coenzyme Q10 that have recorded at least 60 patients and complet at least six months' duration of treatment and measured clinical results A meta-analysis of the efficiency of coenzyme Q10 on indices of cardiac function conclud that its use was associated with a substantial improvement. This conclusion was not confirmed on two subsequent randomized trials. The studies reporting clinical consequences yielded mixed results. Two studies reported distinctly favorable clinical issues for coenzyme Q10-treated patients. However, undivided study probably had a serious potential flaw in design and execution in that it is not reported to be placebo-controlled or blinded with reverence to outcome measurement. The other study is reported in insufficient detail to allow an adequate assessment of the recorded population or the results. Four following studies reported either no or clinically small improvements. Therefore, the value of coenzyme Q10 supplementation in patients with CVD is still an render free of access question, with convincing evidence neither supporting nor refuting evidence of benefit or harm.

* Four studies assessing vitamin C (mostly in combination with vitamin E) provide scant evidence that these combinations of antioxidant complements have any cardiovascular health benefits. The simply reported benefit was in the Antioxidant Supplementation in Atherosclerosis Prevention (ASAP) application of mind and that was in an intermediate consequence only, and then only in the subpopulation of male smoker The Heart Protection reflection in particular, because of its size and follow-up provides upright evidence that these antioxidant postscripts in these doses are unlikely to have any substantial events on CVD outcomes.

COPYRIGHT 2004 American Academy of Family Physicians

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