News:Antioxidants: WACS Study Demonstrates No Significant Benefit From Antioxidants For Preventing CVD

August 15, 2007 By Scott P. Williams [mailto:swilliams@perfuse.org]

Although past studies have demonstrated that diets including high levels of fruit and vegetable consumption are associated with reduced rates of coronary heart disease and stroke, the WACS trial is one of many recent studies concluding that antioxidant rich diets result in no consistent preventive effects on CVD.

The study was a randomized, double-blind, placebo controlled trial that evaluated the effects on patients of receiving 500 mg of vitamin C per day, and 600 IU of vitamin E and 50 mg of beta carotene every other day. Its 2 x 2 x 2 factorial design allowed the research team to evaluate the effects of the three antioxidants in isolation as well as in combination.

The study was populated by 8171 women age 40 or older who were deemed to be at high risk for CVD. The participants were considered high risk if they had a self reported history of CVD, or had at least 3 of the following cardiac risk factors: hypertension, high cholesterol level, diabetes mellitus, parental history of premature MI, obesity, current cigarette smoking, or inconsistent report of prior CVD. 5238 of the trial’s had a prior cardiovascular event, while the other 2933 had at least 3 cardiac risk factors.

The study spanned from June 1995 through July 2005. Data were collected from questionnaires sent to the women every six months for the first year and then annually thereafter. The mean duration of follow up was 9.4 years, with a range of 8.3 to 10.1 years.

During the mean 9.4 year follow up period, the trial found that none of the three antioxidants in isolation showed any reduction in the occurrence of the combined primary endpoint of CVD morbidity and mortality. Further, the data demonstrated no significant 2- or 3- way interactions among the vitamin C, vitamin E and beta carotene with regard to the combined primary endpoint.

Although the three antioxidants did not produce an overall reduction in the incidence of CVD among the trial’s participants, both vitamin C and vitamin E demonstrated, in isolation, a nonsignificant reduction in the secondary endpoint of ischemic stroke. When combined, these two antioxidants showed a significant reduction in the occurrence of  stroke when compared to the placebo group.

The study was limited by a lack of complete follow up and compliance.

Though the study suggests that alone or in combination, vitamin C, vitamin E, and beta carotene may not have preventive effects on CVD, it does indicate that further research on the effects of antioxidants could yield positive benefits in the reduction of stroke.

Nancy R. Cook, ScD; Christine M. Albert, MD; J. Michael Gaziano, MD; Elaine Zaharris, BA; Jean MacFadyen, BA; Eleanor Danielson, MIA; Julie E. Buring, ScD; JoAnn E. Manson, MD, DrPH. A Randomized Factorial Trial of Vitamins C and E and Beta Carotene in the Secondary Prevention of Cardiovascular Events in Women.Arch Intern Med. 2007;167:1610-1618.