Although alcohol is one of the main causes of illness, disability and death in the population, some studies have observed certain benefits in the consumption of small amounts. Specifically, epidemiological studies (mainly in Anglo-Saxon countries) argued that consuming one or two cups of alcoholic beverages per day was associated with lower mortality because deaths due to cardiovascular disease were reduced.
However, the quality of these investigations has recently been questioned due to various methodological problems. To overcome these limitations and to clarify whether alcohol consumption influences mortality, researchers from the Autonomous University of Madrid (UAM), the Biomedical Research Consortium in the Epidemiology and Public Health Network (CIBERESP) and the Madrid Institute for Advanced Studies in Food (IMDEA-Food) investigated 3,045 people over 60 years of age representing the Spanish population.
The study began in the period 2008-2010 collecting data on alcohol consumption (at that time and at the different decades of life), and on lifestyles, diseases and functional limitations. Subsequently, the participants were followed until 2017 to identify the deaths that occurred since the beginning of the study.
“When analyzes used alcohol consumption throughout life to avoid selection bias, there was no difference in mortality between participants who did not drink at all and those who drank moderate amounts of alcohol (this is up to three drinks a day in men and up to two drinks a day in women),” the authors explain.
“However, in those who drank larger amounts, mortality was double that in non-drinkers. When only people without functional limitations were investigated to reduce the reverse causality, mortality increased by 12% for each daily alcoholic drink.”
Thus, the new results, published in the journal Addiction, do not show any benefit on mortality derived from consuming small and moderate amounts of alcohol.
Methodological problems overcome
Rosario Ortolá, first signatory of the study and researcher at the Autonomous University of Madrid (UAM), points out that “health professionals can use these results in clinical practice: never recommend alcohol consumption to patients. And if these drink because they do not have diseases that are aggravated by alcohol and do not take medications that interact with it, the recommendation should always be the same: ‘the less, the better’.”
One of the problems in the previous works is the errors in the selection of the participants in the studies. For example, in some studies the apparent lower mortality of those who drank some alcohol could be due to the fact that they are compared with non-drinkers, who also include ex-drinkers (many of them stopped drinking due to health problems and, therefore, they have more risk of dying).
One possible solution is to assign ex-drinkers to the different categories of drinkers according to the amount of alcohol they consumed throughout their lives, until they abandoned the drink.
Another problem is that part of the possible benefits of alcohol in some previous studies may be due to the effect of the state of health on the consumption of alcohol, and not vice versa. In particular, it is known that healthy people consume more alcohol altogether than the sick, because they stop doing so or reduce consumption when they are diagnosed. This methodological problem, known as ‘reverse causality’, can be alleviated by studying only people in good health.