Drinking three alcoholic drinks a day can cause liver cancer, research has suggested.
Being overweight or obese and consuming foods contaminated by aflatoxins (toxins produced by certain fungi) also showed “strong evidence” of causing the disease, the World Cancer Research Fund said.
Its research, which analysed 34 studies involving 8.2 million people, more than 24,500 of whom had liver cancer, also suggested higher consumption of coffee “probably” protects against liver cancer, while physical activity and fish consumption may also decrease the risk although further research is needed.
Aflatoxins are produced by inappropriate storage of food and are generally an issue related to foods from warmer regions of the world. Foods that may be affected include cereals, spices, peanuts, pistachios, Brazil nuts, chillies, black pepper, dried fruit and figs.
The study said the “overall evidence was consistent with a positive dose-response relationship for alcohol and liver cancer”.
“There was ample evidence suggestive of a non-linear relationship with a statistically significant effect above about 45 grams per day.
“No conclusion was possible for intakes below 45 grams per day. The CUP (Continuous Update Project) panel concluded the consumption of alcoholic drinks is a convincing cause of liver cancer. This is based on evidence for alcohol intakes above about 45 grams per day (around three drinks a day).”
The report, described as the most comprehensive review to date of global research into the relationship between diet, weight, physical activity and liver cancer, said women should try to limit their alcohol intake to one drink per day and men to two drinks a day.
Other recommendations included being as lean as possible without becoming underweight and carrying out physical activity for at least 30 minutes every day.
Liver cancer is one of the most deadly cancers with just a 12% survival rate after five years.
Nearly a quarter of cases could be prevented if people kept a healthy weight and did not drink, the charity said.
Director of World Cancer Research Fund UK, Amanda McLean, said: “Around three or more drinks per day can be enough to cause liver cancer.
“Until now we were uncertain about the amount of alcohol likely to lead to liver cancer. But the research reviewed in this report is strong enough, for the first time, to be more specific about this.”
David Spiegelhalter, Winton Professor of the Public Understanding of Risk at the University of Cambridge, said the research had been presented in a “misleading” way.
“The increase in risk of liver cancer per 10g alcohol consumed is only about 4%- so while it ’can cause’ cancer, that level of alcohol is extremely unlikely to,” he said.
“And the report says that this risk increase only starts at levels above about 45g of alcohol per day, but this is 5.5 units, which is already a lot of alcohol (about equivalent to 500mls of 11% wine).
“Following on from this, increasing alcohol consumption from 500mls (two thirds of a bottle of wine per day) to a whole bottle day is an extra 22g of alcohol and subsequently increases risk of liver cancer by 10%.
“Liver cancer is rare: about one in 100 men and one in 200 women get it in their lifetime. So if you already drink a lot, and then drink even more, your risk goes up a small amount.”