People living in colder countries with less annual sunlight are more likely to have alcoholic liver disease, scientists say.
Many chilly northern countries have a reputation for hard drinking. Russia being a prime example, where adults on average drink the equivalent of more than 11 litres of pure alcohol a year, according to World Health Organization data.
Now scientists say they have found the first basic statistical analysis to link life in cold, dark countries with liver cirrhosis caused by heavy alcohol intake.
Alcoholic cirrhosis is the most advanced stage of alcohol-induced liver damage, caused by scarring of the organ due to chronic high intake of alcohol, according to the NHS.
The researchers, from University of North Carolina at Chapel Hill in the US, presented their findings at the International Liver Congress 2017 in Amsterdam.
"We were very surprised that what everyone assumed about alcoholic liver disease and colder climates had never been analysed," study author Ramon Bataller told IBTimes UK.
"No one had looked at whether people were more likely to get this disease if they lived in a country with lower average temperatures or less annual sunlight."
The study authors used data from the WHO and the World Meterological Organization for 193 countries. They found a basic association between the two: The colder and darker a country was, the more cases of alcoholic liver disease it had. This doesn't mean it is a causal relationship, but it does show that there is a correlation.
A more nuanced analysis took into account several other factors known to affect the number of cases of liver disease in a country, such as the prevalence of binge drinking, and hepatitis B and C.
"The pattern of drinking may influence the amount of alcohol that one drinks, and there's a dose response with alcohol and cirrhosis," said Neil Shah.
The effect of temperature and sunlight in a country still appeared to have an effect after taking these other risk factors into account.
Several factors such as access to home-made alcohol, which is not picked up in official data, weren't taken into account in the study. These, and the relationship of wealth inequalities, alcohol intake and liver disease are planned to be explored in a larger, more detailed study, says Shah.