Alcohol consumption has been linked to a reduced risk of non-fatal heart attacks, but an increased risk of stroke, an analysis of nearly 600,000 current drinkers in 83 prospective studies revealed.
The study, led by Dr Angela Wood, of the University of Cambridge, looked at individual-participant data taken from three large-scale data sources in 19 high-income countries (the Emerging Risk Factors Collaboration, EPIC-CVD, and the UK Biobank). Controls for age, smoking, history of diabetes, level of education and occupation were included.
To be eligible for the analysis, participants had to have information recorded about their alcohol consumption amount and status (i.e., non-drinker vs current drinker), plus age, sex, history of diabetes and smoking status, at least 1 year of follow-up after baseline, and no baseline history of cardiovascular disease.
The researchers then focused their attention on current drinkers, whose baseline alcohol consumption was categorised into eight predefined groups according to the amount in grams consumed per week. Alcohol consumption was then assessed in relation to all-cause mortality, total cardiovascular disease, and several cardiovascular disease subtypes.
The researchers found that, of the 599,912 current drinkers included in the analysis, 40,310 deaths and 39,018 incident cardiovascular disease events during 5·4 million person-years of follow-up.
In cases of all-cause mortality, they recorded a positive and curvilinear association with the level of alcohol consumption, with the minimum mortality risk around or below 100g per week.
Furthermore, alcohol consumption was roughly linearly associated with a higher risk of stroke (HR per 100 g per week higher consumption 1·14, 95% CI, 1·10–1·17), coronary disease excluding myocardial infarction (1·06, 1·00–1·11), heart failure (1·09, 1·03–1·15), fatal hypertensive disease (1·24, 1·15–1·33); and fatal aortic aneurysm (1·15, 1·03–1·28).
However, by contrast, increased alcohol consumption was also associated with a lower risk of myocardial infarction (HR 0·94, 0·91–0·97).
In comparison to those who reported drinking 100–≤200g per week, >200–≤350g per week, or >350g per week had lower life expectancy at age 40 years of approximately 6 months, 1–2 years, or 4–5 years, respectively, when compared with those who drank less than 100g of alcohol per week.
This led the researchers to believe that, in current drinkers of alcohol in high-income countries, the threshold for lowest risk of all-cause mortality was about 100g/week. This is lower than the recommended intake in most current guidelines. For reference, 100g/week of alcohol would be equivalent to five drinks per week – about five pints of 4% beer or five 175ml glasses of 13% wine.
The UK’s current guidance is that men and women should drink no more than 14 units of alcohol per week – or around six pints of beer or six glasses of wine.