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Recently, results from the Physicians’ Health Study II were to be presented at the American Heart Association’s 2008 Scientific Sessions.

The study had found neither vitamin C nor vitamin E supplementation to have an effect in reducing major cardiovascular outcomes, when compared to placebo.

However, the study also highlighted some limitations of its findings. First, it only included male physicians in the US. Exposure and some endpoint assessments were also obtained using a questionnaire which was mailed, and thus bias could have affected its collated results.

Further, the subjects were followed for a mean period of 8 years. This may not have been sufficient to establish any link, and it is possible that a longer period of follow-up would have caused correlations to show up. In addition, it is also possible that a different dose might have caused a visible difference.

The fact is, the two vitamins had been linked in earlier epidemiological studies to improved cardiovascular outcomes. Thus, we should not ditch their potential usefulness in preventing and combating the disease.

In response to the study, the Council for Responsible Nutrition (CRN), which is a trade association representing the dietary supplement industry, issued a statement.

Said Andrew Shao, PhD, vice president of scientific and regulatory affairs of CRN, “We commend the researchers for undertaking this important prevention trial which sought to confirm positive results demonstrated by earlier observational trials on these antioxidant vitamins. Although the results did not demonstrate an overall benefit, the results also do not discount the earlier epidemiological data showing that people with high intakes of vitamins E and C may have a lower risk of cardiovascular disease. Nutrition research is extremely complex, and doesn’t always provide clear cut answers. This study raises an interesting set of scientific challenges as to why the benefits found in observational studies have not been confirmed in this kind of trial.”

“From a consumer’s point of view, it can be frustrating to have more questions than answers, but for scientists, this can be intriguing. The truth is, we don’t have conclusive scientific evidence in the form of randomized, controlled trials that demonstrate exactly how to prevent cardiovascular disease. We do know there are some well-known practical approaches — like not smoking, maintaining a healthy weight, consuming a diet with a variety of foods, regular exercise, seeing your physician, and responsible use of vitamin supplements. Consumers should not take vitamins expecting that vitamins alone will prevent cardiovascular disease, but they should continue to take vitamins for the general health benefits they provide.”

Annette Dickinson, Ph.D., consultant and past-president of CRN, also said, “This important study is another in a series of clinical trials that generally have failed to confirm hopes of identifying a strong preventive effect of vitamin E, vitamin C or other antioxidants in relation to cardiovascular disease. The trials were undertaken because of strong positive evidence from epidemiological studies, and the reasons for the different results in clinical trials remain to be clarified. Potentially relevant factors pointed out by the authors of this study include dose, duration, and combinations of nutrients.”

“With regard to the possible effect of vitamin E on increased risk of hemorrhagic stroke, this has been a subject of discussion ever since the ATBC trial of male smokers in Finland reported such an effect in 1994 with a dose of only 50 IU of vitamin E. Such an effect was not seen in numerous other trials using higher levels of vitamin E (300 to 600 IU), but was observed in this study using 400 IU every other day (equivalent to 200 IU per day). The absence of such an effect in studies with higher doses raises the question whether this occurred by chance.”

“These results do not of course negate other evidence of benefits for vitamin E and vitamin C for other conditions, including immune function, mental acuity, and eye health. Consumers would be well advised to ensure adequate intakes of all essential nutrients through a good diet plus use of a multivitamin, and selected other nutrients including vitamins E and C, vitamin D, calcium, and EPA and DHA omega-3 fatty acids.”

Sources: CardioSource.com and MarketWatch.com

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