BMJ 2000;320:1378-1379 ( 20 May )
A paper was published in the BMJ on the 20th May by Martin Bobak, Senior Lecturer of Epidemiology and public health at University College London and Zdenka Skodova from the Department of preventative cardiology at the institute of Clinical and Experimental Medicine in Prague. The paper, entitled 'The Effect of beer drinking on risk of myocardial infarction: population based case-control study' analysed the protective effect of ethanol versus different drink types.
Many studies have shown an inverse association between alcohol consumption and coronary heart disease, with a possible flattening at higher consumption levels.1 It remains unclear, however, whether the protective effect is confined to specific beverages (such as red wine) or relates to ethanol. This question is complicated because wine drinkers may differ from people drinking other beverages or have a different drinking pattern.They addressed this issue by conducting a study in the Czech Republic, a predominantly beer drinking country, and by restricting the analyses to people who did not drink wine or spirits.
A population based case-control study in five Czech districts of men aged 25-64 who had a first non-fatal myocardial infarction that fulfilled the World Health Organization MONICA (monitoring trends and determinants in cardiovascular disease) criteria of definite or probable infarction2 over 18 months were considered eligible. All cases agreed to participate in the study. An age stratified random sample of the population (response rate 77%) served as controls. Data on cases and controls were collected by identical protocols
Participants reported the frequency of drinking any alcohol (never; less than once a month; once or twice a month; several times a week; almost daily or daily; and twice a day or more often). They also reported how much wine, spirits, and beer they consumed during a typical week. The average consumption of pure alcohol was 148 g a week, 87% of which was consumed as beer. The analyses were restricted to non-drinkers and "exclusive" beer drinkers.
Participants were categorised into four groups according to their average weekly intake of beer: <0.5 l (about 18 g of alcohol), including non-drinkers; 0.5-3.9 l (18-144 g of alcohol); 4-8.9 l (145-324 g of alcohol); and 9 l (325 g of alcohol).
The lowest risk was found among men who drank almost daily or daily (adjusted odds ratio 0.38, 95% confidence interval 0.19 to 0.75) and among men who drank 4-8.9 l of beer a week (0.34, 0.19 to 0.61) (table 1). When beer intake was analysed in narrower categories, the lowest risk was found for weekly consumption of 5-6 l, but because of the small numbers of subjects in each category the confidence intervals were wide (not shown). The results did not change when men with a history of heart disease, stroke, diabetes, or cancer were excluded.
In this study of beer drinkers, the lowest risk of myocardial infarction was found among men who drank almost daily or daily and who drank 4-9 litres of beer a week. There was a suggestion that the protective effect was lost in men who drank twice a day or more. This is similar to results of studies of other beverages. These results support the view that the protective effect of alcohol intake is due to ethanol rather than to specific substances present in different types of beverages.
Funding: The study was funded by a grant from the Wellcome Trust and by the Czech Ministry of Health. MB was supported by the Wellcome Trust fellowship in clinical epidemiology. MM is supported by an MRC research professorship.
Source: Bobak et al BMJ 2000: 320: 1378-1379 (20th May 2000)