:: If you drink alcohol, whether beer, wine or spirits, moderate your consumption to two drinks per day if you are a man and one drink per day if you are a woman

There is wide variability among European Union countries in terms of per capita average alcohol consumption and preferred type of alcoholic beverage figure2. Although three groups of countries are traditionally identified according to the prevalent drinking culture (wine drinking in the South, beer drinking in the Central Europe and spirit drinking in the North), there is considerable variability within such groups and within countries, and new patterns are evolving rapidly (e.g. increasing consumption of wine in northern countries; increasing prevalence of binge drinking, in particular among women).

There is convincing epidemiological evidence that the consumption of alcoholic beverages increases the risk of cancers of the oral cavity, pharynx and larynx and of squamous cell carcinoma of the oesophagus. The risks tend to increase with the amount of ethanol drunk, in the absence of any clearly defined threshold below which no effect is evident.

Although alcohol drinking increases the risk of upper digestive and respiratory tract neoplasms, even in the absence of smoking, alcohol drinking and tobacco smoking together greatly increase the risk of these cancers, each factor approximately multiplying the effect of the other. Compared to never-smokers and non-alcohol drinkers, the relative risk of these neoplasms is increased between 10- and 100-fold in people who drink and smoke heavily figure3. Indeed, in the case of total abstinence from drinking and smoking, the risk of oral, pharyngeal, laryngeal and squamous cell oesophageal cancers in European countries would have been extremely low.

A likely carcinogenic mechanism of alcohol is by facilitating the carcinogenic effect of tobacco and possibly of other carcinogens to which the upper digestive and respiratory tract are exposed, particularly those of dietary origin. However, a direct carcinogenic effect of acetaldehyde, the main metabolite of ethanol, and of other agents present in alcoholic beverages cannot be excluded. A diet poor in fruits and vegetables, typical of heavy drinkers, is also likely to play an important role. There does not seem to be a different effect of beer, wine or spirits on cancer risk at these sites; rather the total amount of ethanol ingested appears to be the key factor in determining the increase in risk. Only a few studies have analysed the relationship between stopping alcohol drinking and the risk of cancers of the upper respiratory and digestive tract. There is clear evidence that the risk of oesophageal cancer is reduced by 60% 10 years or more after drinking cessation. The pattern of risk is less clear for oral and laryngeal cancers. Stopping (or reducing) alcohol drinking, particularly in association with smoking cessation, represents a priority for preventing oesophageal cancer.

Alcohol drinking is also strongly associated with the risk of primary liver cancer; the mechanism however might be mainly or solely via the development of liver cirrhosis, implying that light or moderate drinking may have limited influence on liver cancer risk. Moreover, there is some evidence suggesting that heavy alcohol consumption is particularly strongly associated with liver cancer among smokers and among people chronically infected with Hepatitis C virus (HCV).

An increased risk of colorectal cancer has been observed in many cohort and case–control studies, which seems to be linearly correlated with the amount of alcohol consumed and independent from the type of beverage.

An increased risk of breast cancer has been consistently reported in epidemiological studies conducted in different populations. Although not strong (increased risk in the order of 10% for each 10 g/day increase in alcohol intake, possibly reaching a plateau at the highest levels of intake), the association is of great importance because of the apparent lack of a threshold, the large number of women drinking a small amount of alcohol and the high incidence of the disease. Indeed, more cases of breast cancer than of any other cancer are attributable to alcohol drinking among European women table8. It has been suggested that alcohol acts on hormonal factors involved in breast carcinogenesis, but the evidence is currently inadequate to identify a specific mechanism.

Besides increasing cancer risk, alcohol drinking entails complex health consequences, making it difficult to formulate universal public health guidelines. There is strong evidence for a J-shaped pattern of risk of total mortality and cardiovascular disease according to increasing alcohol consumption figure4. This classic pattern is one of decreased risk in light drinkers compared with non-drinkers and then an increasing risk as alcohol consumption increases. In addition, alcohol drinking increases the risk of injuries in many types of motor vehicle, leisure and occupational injuries (e.g. driving, swimming, manual working) and accident mortality rates are influenced by per capita alcohol consumption across Europe. Moreover, drinking alcohol during pregnancy has a detrimental effect on the development of the foetus and its central nervous sytem, often resulting in malformations, behavioural disorders and cognitive deficits in the postnatal period.

For these reasons, the task of fixing a threshold on daily alcohol intake below which the increased risk of cancer and other diseases is offset by a reduced risk of cardiovascular diseases is not simple. Factors such as age, physiological condition and dietary intake certainly modify any such threshold: in particular, the beneficial effects on cardiovascular diseases appear only at middle age.

In conclusion, there is evidence showing that a daily alcohol intake as low as 10 g/day (that is, approximately, one can of beer, one glass of wine or one shot of spirit) figure5 is associated with some increase in breast cancer risk relative to non-drinkers, while the intake associated with a significant risk of cancer at other sites (such as cancers of the upper digestive and respiratory tracts, liver or colorectum) is probably somewhat higher (approximately 20–30 g/day).

All the above points should be considered to give sensible advice regarding individual recommended limits of alcohol consumption. The limit should not exceed between 20 g of ethanol per day (i.e. approximately two drinks of either beer, wine or spirit each day) and it should be as low as 10 g per day for women.