Just one alcoholic drink a day slightly increases an individual’s risk for health problems, according to a large new study. No level of alcohol consumption conferred any health benefits, the authors also concluded, a finding that runs contrary to much previous research and public health guidelines in many countries.

The analysis, involving 195 countries and territories from 1990 to 2016, relied on 694 sources of data and analysed 592 studies to determine the health risks of alcohol use. While the study is among the largest of its kind, it was also observational, linking population-wide consumption to population-wide trends.

Researchers relied on sales data and surveys to estimate the prevalence of drinking in each country and calculated alcohol consumption in standard drinks daily, defined as 10 grams, or about one-third of an ounce, of pure ethyl alcohol — the equivalent of 3.4 ounces (100ml) of red wine at 13 per cent alcohol, 12 ounces (355ml) of beer at 3.5 percent alcohol, or 1 ounce (30ml) of 80-proof whiskey.

They also devised a method for distinguishing alcohol consumption among tourists from that of the resident populations, and linked consumption data to 23 health outcomes, ranging from car accidents, suicides and tuberculosis, to liver cirrhosis, cardiovascular disease and cancers.

In 2016, 25 per cent of women and 39 per cent of men were drinkers — about 2.4 billion people worldwide. Women had an average of 0.73 drinks a day, while men had 1.7 drinks.

Rates of alcohol consumption vary widely by country, but in general the higher a country’s income level, the higher the prevalence of drinking.

The study, published in the journal, The Lancet, concluded that alcohol consumption is involved in 2.8 million deaths annually worldwide, making it the seventh leading risk factor for death and disability.

Among people between the ages of 15 to 49, alcohol use is the single most common risk factor for death and disability. In 2016, alcohol accounted for 6.8 per cent of male and 2.2 per cent of female deaths.

“The main difference between alcohol consumption and smoking is that no one is surprised that smoking is bad,” said the lead author, Emmanuela Gakidou, a professor of health metrics sciences at the University of Washington in the US.

“But there’s a lot of surprise, even among experts, that alcohol is as bad for you as it is.”

Many studies and most health guidelines suggest that moderate drinking — one or two drinks a day — is safe and may even reduce the risk of heart disease, stroke or diabetes.

But Gakidou and her colleagues found that just one drink a day for one year increases alcohol-related health problems slightly, to 918 per 1,00,000 people from 914 per 1,00,000. The only truly safe level of alcohol consumption, the researchers concluded, is therefore zero.

Other experts were not convinced. Online in Medium [a publishing platform], David Spiegelhalter, a statistician at Cambridge University in England, wrote of the study’s conclusion: “Claiming there is no ‘safe’ level does not seem an argument for abstention. There is no safe level of driving, but governments do not recommend that people avoid driving.”