A healthy dose of scepticism: four good reasons to think again about protective effects of alcohol on coronary heart disease.

ISSUES: Alcohol has been implicated in both the popular press and scientific literature as having a protective effect for at least a dozen conditions including coronary heart disease (CHD). APPROACH: Epidemiological evidence for an apparent protective effect of alcohol on CHD is now being challenged on a number of fronts. This paper is a synopsis of those various challenges as they currently stand. KEY
FINDINGS: The argument that systematic misclassification of ex-drinkers and occasional drinkers to 'abstainer' categories among epidemiological studies might explain apparent protective effects of moderate alcohol consumption on CHD has recently been supported by new meta-analyses and independent research. The influence of uncontrolled or unknown factors on the relationship between alcohol and disease cannot be ruled out. Exclusion of participants on the basis of ill-health severely reduces study sample size and new analyses suggest that doing so might artificially create the appearance of protective effects. The ability of respondents to accurately recall their own alcohol consumption is in serious doubt and very few individuals maintain one single drinking level or style throughout life. The relationship between alcohol and some conditions might be a function of drinking patterns but few studies have addressed the issue. IMPLICATIONS: Popular perceptions regarding the strength of evidence for alcohol's protective effect on a growing number of conditions might be misguided.
CONCLUSION: It is time for the wider research, health and medical community to seriously reflect on the quality of current evidence for apparent protective effects of alcohol on human disease.