Ir Med J. 2005 Sep;98(8):230-1      


Background
Theories about the potential health benefits of moderate alcohol consumption have been evolving in modern medicine for almost a century now, since Pearl’s work on the relationship between alcohol intake and reduced mortality.¹² Although this work was largely ignored by the medical profession at the time, the principal findings are now widely accepted among the profession and the general public alike; up to a hundred epidemiological studies conducted over the past three decades have demonstrated that moderate drinkers seem to be healthier and seem to have lower mortality rates than non-drinkers and heavy drinkers, the so-called U or J shaped curve.² The resulting assumption has been that the pharmacological properties of alcohol, when consumed in moderation, have significant health benefits, especially with respect to cardiovascular disease. As a result, some expert groups have advised, albeit with caution, moderate alcohol consumption for middle aged and older men and post-menopausal women, i.e. those individuals at highest risk of cardiovascular disease.³

Other perceived benefits of moderate alcohol consumption include reductions in the risk of ischaemic stroke, dementia, diabetes and a consequent overall reduction in total mortality.⁶ The theoretical basis to the ‘French paradox’ has further popularized beliefs about the benefits of alcohol consumption, particularly in relation to red wine consumption and cardiovascular disease. Higher levels of red wine consumption among the French population has been proposed as the reason for their lower levels of ischaemic heart disease in comparison to countries in northern Europe and the United States, despite a high dietary fat intake in France.⁸

However, the many adverse effects of alcohol intake for the individual and society in general tend to be deemphasized in such discussions, perhaps overshadowed by the enthusiasm generated by the potential for reductions in ischaemic heart disease, one of the leading causes of death worldwide.¹⁵ Furthermore, there are inherent difficulties associated with interpreting epidemiological data.

Problems with epidemiological evidence
One of the criticisms of epidemiological studies examining the health consequences of alcohol intake is that a large proportion of non-drinkers may be ex-drinkers who stopped drinking because of alcohol problems or other health problems (so called ‘sick quitters’), and so may be less healthy than moderate drinkers for reasons other than their current drinking habits.¹⁴

Moderate drinkers have also been demonstrated to have other favourable (and cardioprotective) health characteristics such as lower levels of smoking, lower body mass index and higher exercise levels.¹⁶ Personality type is a potential confounder that has not been controlled for in epidemiological studies to date. Introverted personality type has been demonstrated to be an independent risk factor for hypertension in some individuals;¹ higher levels of introversion among non-drinkers may be a factor in their apparently increased risk of cardiovascular disease.¹¹

The specific cardiovascular benefits of wine consumption, compared to other alcoholic beverages, have been questioned by a more recent study.⁹ Furthermore, a ‘time-lag’ hypothesis has been raised. The originators of this theory argue that the dietary habits of the French and the British have been similar for only the past fifteen to twenty years and that up until that time, the French had lower levels of animal fat consumption and lower serum cholesterol levels. They argue that decades of exposure to high levels of cholesterol must elapse before it is reflected in the ischaemic heart disease rates of a population.⁵

Questions have also been raised about the biological plausibility of alcohol’s apparent cardioprotective effects. A meta-analysis has demonstrated an improvement in the profile of cardiovascular biomarkers (lipid and thrombolytic profile) with moderate (30g daily) alcohol intake.¹³ However, only controlled trials of alcohol versus placebo and conventional lipid lowering and anti-platelet agents can definitively answer the question of alcohol’s efficacy in this regard. There are methodological and ethical barriers to such trials. Double-blinding would not be possible in view of the neurobehavioural effects of alcohol. Furthermore, most individuals with cardiovascular disease in industrialized countries would already be taking conventional medications with a proven evidence base; it would be unethical to stop such medication for some individuals and ‘treat’ them with alcohol instead.

In this era of evidence based medicine, alcohol would not get a license for the treatment and prevention of heart disease.

Recommendations
So what can we recommend to our patients? There is no evidence base to support a recommendation for non-drinkers to start drinking. Furthermore, non-drinkers may have definite reasons for not drinking in the first place, such as religious persuasion, a past personal or family history of alcoholism, or certain medical or psychiatric conditions.

For those who currently drink, any health benefits of alcohol, particularly relating to cardiovascular disease, are most apparent in those at highest risk, i.e. older men and postmenopausal women, and in those who drink approximately one drink on most days of the week.⁷

However, there are obvious adverse health consequences associated with excessive alcohol intake and binge drinking, for the individual and society in general.⁴ Therefore, moderation must be stressed, if not for it’s apparent health benefits, but for the prevention of a myriad of medical and psychosocial problems. These problems are particularly evident in younger people and in those who binge drink.⁴ The apparent balance in favour of health benefits in older people who drink moderately may, however, be related to a lack of awareness of the frequently covert nature of alcohol related problems in older people.¹⁰

Therefore, despite the wealth of epidemiological evidence demonstrating that moderate drinkers seem healthier and seem to have lower levels of cardiovascular disease, and the fact that moderate alcohol intake has been demonstrated to improve the profile of biomarkers of cardiovascular disease, there is insufficient evidence at present to support advising moderate alcohol intake for the entire population. Future research in the area should focus on eliminating potential confounding factors in epidemiological observations, such as personality type and certain health and lifestyle factors, such as diet, exercise levels and body mass index. Furthermore, more research should focus on identifying the biological mechanisms that may mediate any health benefits of alcohol. At a clinical level, we should discuss alcohol intake with patients on an individual basis, stressing the adverse health consequences of excessive and binge drinking.

H O’Connell, B Lawlor
Department of Psychiatry,
St. James' Hospital, Dublin 8

Correspondence: Henry O'Connell,
Limerick Mental Health Services,
Trevor Day Hospital, Limerick
E-Mail: [email protected]

References

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15. World Health Organization. www.who.int accessed 6/1/2005.