BACKGROUND:Studies suggest that moderate drinkers have lower cardiovascular disease (CVD) mortality than nondrinkers and heavy drinkers, but there have been no randomized trials on this topic. Although most observational studies control for major cardiac risk factors, CVD is independently associated with other factors that could explain the CVD benefits ascribed to moderate drinking.METHODS:Data from the 2003 Behavioral Risk Factor Surveillance System, a population-based telephone survey of U.S. adults, was used to assess the prevalence of CVD risk factors and potential confounders among moderate drinkers and nondrinkers. Moderate drinkers were defined as men who drank an average of two drinks per day or fewer, or women who drank one drink or fewer per day.RESULTS:After adjusting for age and gender, nondrinkers were more likely to have characteristics associated with increased CVD mortality in terms of demographic factors, social factors, behavioral factors, access to health care, and health-related conditions. Of the 30 CVD-associated factors or groups of factors that we assessed, 27 (90%) were significantly more prevalent among nondrinkers. Among factors with multiple categories (e.g., body weight), those in higher-risk groups were progressively more likely to be nondrinkers. Removing those with poor health status or a history of CVD did not affect the results.CONCLUSIONS:These findings suggest that some or all of the apparent protective effect of moderate alcohol consumption on CVD may be due to residual or unmeasured confounding. Given their limitations, nonrandomized studies about the health effects of moderate drinking should be interpreted with caution, particularly since excessive alcohol consumption is a leading health hazard in the United States.