Reducing cholesterol and blood pressure, as well as smoking cessation, have been shown to be effective strategies for preventing cardiovascular diseases. 1 However, these "classical" risk factors, along with known non-modifiable risk factors such as age, sex, and family history, cannot fully explain why some people develop myocardial infarction and stroke, while others do not. [2][3][4] Additional factors may have a role in the pathogenesis of atherosclerosis, and new preventive strategies may be of use. In this article we briefly review the use of antioxidants, the use of angiotensin converting enzyme inhibitors, and homocysteine lowering; other "emerging" cardiovascular risk factors and potential preventive strategies that are under investigation are summarised in table 1.
Oxidative stress and antioxidantsExtensive laboratory data show that oxidative modification of low density lipoprotein cholesterol is an important step in the pathogenesis of atherosclerosis, and experimental studies in different animal models show that antioxidants decrease oxidation of low density lipoprotein cholesterol and reduce plaque formation.
6Epidemiological studies have generally reported that increased intake of antioxidants through diet or supplements, particularly vitamins E and C and carotene, is associated with a lower risk of coronary heart disease. [7][8][9] Other antioxidants, such as other carotenoids, flavonoids, selenium, magnesium, and monounsaturated fat, are also found in natural food products and may reduce oxidation of low density lipoprotein cholesterol. The most compelling results have been with vitamin E supplementation. [10][11][12] However, these epidemiological studies have several methodological limitations. While most observational studies have attempted to "statistically" adjust for other factors that could affect the cardiovascular risk, such adjustments are difficult and not always adequate. Lifestyle and dietary patterns not accounted for could contribute to some of the observed apparent lower cardiovascular risk in people who use supplemental vitamins in comparison to non-users, and similar confounders could bias the results of epidemiological studies evaluating dietary intake of antioxidant vitamins.Therefore, the role of specific vitamins in the prevention of coronary heart disease is best evaluated in randomised clinical trials.
Trials of vitamin EThree large randomised placebo controlled trials of vitamin E have been completed (table 2). The alpha-tocopherol beta carotene cancer prevention study (ATBC) was designed primarily to assess the effects of daily supplementation with tocopherol and carotene on cancer. 13 A total of 29 133 Finnish male smokers were randomly assigned to tocopherol (vitamin E) 50 mg daily or placebo and carotene 20 mg daily or placebo for 5-7 years. Vitamin E did not prevent death from cardiovascular disease or myocardial infarction. The incidence of angina pectoris was modestly reduced (relative risk reduction = 9%, 95% confidence interval 1% to 17%; P = 0.04).14 In the s...
