Vitamins and Antioxidants
Impact on Heart Disease
In the mid 1990's, some studies suggested that vitamin E consumption would help prevent coronary heart disease (CHD). One such study, published in reference 1, studied 34 thousand postmenopausal women. Their intake of vitamins A, E and C from food sources and from supplements were assessed using a questionnaire. After approximately 7 years of followup, 242 of the women died of CHD. The study determined that vitamin E consumption appeared to be linked inversely with the risk of death from CHD, particularly among those women who did not consume vitamin supplements! The risk of CHD was reduced (for highest vitamin E consumption relative to the lowest) by a whopping factor of RR=0.4 (0.2 to 0.8 Margin of Error). There was no evidence that any of the vitamin supplements impacted the risk of CHD! However, previous studies, such as those published in reference 2 did find an association between vitamin E supplement consumption and reduced risk for CHD.
The seemingly conflicting conclusions were resolved by randomized, double-blind studies. A study of vitamin E supplementation in approximately 9,500 men and women at high risk for cardiovascular disease, was published in references 3 and 4. The participants were randomly assigned to taking a placebo, or a vitamin E supplement of 400 IU/day, for 4.5 years. The participants that took vitamin E did not have a different risk of coronary disease, compared to the patients who took a placebo.
An even larger trial (reference 5) involved almost 21,000 men and women, aged 40 to 80, at high risk for cardiovascular disease. The participants were randomly assigned to a placebo group, or to supplemenation of 900 IU vitamin E, 250 mg vitamin C and 20 mg beta-carotene daily, for a 5 year treatment period. The study found no difference in all-cause mortality between the two groups, or in the incidence of cardiovascular disease. A similar conclusion can be drawn for vitamin C alone (reference 6) - women taking 500 mg a day, for approximately 3 years had the same risk for coronary atheroclerosis (build-up of plaque on the artery lining) comparing to women taking a placebo.
The bottome line: to date, there is no clearly identified effect (positive of negative!) of antioxidant multivitamins on heart disease.
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