Drinking very hot beverages ‘probably’ causes cancer, scientists have claimed.
They said it could cause the disease in the oesophagus, the tube that connects the throat and the stomach.
The claim, made by scientists from the World Health Organisation’s cancer agency, came as they backtracked on whether coffee was a carcinogenic.
The International Agency for Research on Cancer (IARC) said in 1991 that drinking coffee possibly causes bladder cancer, although they were keen to point out this assessment was based on limited evidence and could be wrong.
They now say, however, there is no ‘conclusive evidence’ that drinking coffee causes cancer.
Christopher Wild, director of IARC, said: “These results suggest that drinking very hot beverages (over 65°C) is one probable cause of oesophageal cancer and that it is temperature, rather than the drinks themselves, that appears to be responsible.”
IARC say, however, that this study has not proven coffee to be safe – rather there is not enough evidence to link the drink to cancer.
The agency says coffee is unlikely to be a cause for breast, prostate and pancreas cancer but there was insufficient evidence to reach a conclusion for 20 other types of the disease.
The link between very hot drinks and cancer was based on studies in Iran, Turkey, China and South America, where tea and maté are consumed at high temperatures.
“Smoking and alcohol drinking are major causes of oesophageal cancer, particularly in high-income countries,” added Dr Wild. “However, the majority of oesophageal cancers in parts of Asia, South America and East Africa, where regularly drinking very hot beverages is common and where the reasons for the high incidence of this cancer are not as well understood.”
Paul Pharoah, professor of Cancer Epidemiology at the University of Cambridge, said: “In this report ‘drinking very hot beverages’ have been classified as a group 2A cancer hazard, specifically cancer of the oesophagus. This means it is probable that drinking very hot beverages is causally associated with cancer of the oesophgus, but it does not have any implication for what the magnitude of that risk is.
“This finding is of limited relevance to people in the UK as it is very uncommon for people here to drink tea (or coffee) at temperatures defined by IARC as very hot (less than 65°C).
“In the past (in 1991) IARC had classified coffee drinking as a Group 2B cancer hazard, but with a large body of new evidence available since then, coffee drinking has been downgraded to a Group 3 meaning there was inadequate evidence to link coffee drinking to a risk of cancer. In other words we should not be worried about drinking coffee because of any possible risk of cancer.”
Bill Murray, president of the National Coffee Association, said: “The World Health Organisation’s IARC finding is great news and highly significant for coffee drinkers and confirms evidence from an avalanche of studies by highly respected and independent scientists.
“IARC considered all the science, concluding that regular coffee consumption could reduce the risk of liver cancer and a cancer in the lining of the uterus.
“Separate analysis, from Harvard University amongst others, that followed millions of people suggests that coffee drinkers live longer than non coffee drinkers. In fact, research suggests this amazing beverage may actually help lower the risk of many different cancers and drinking between one and five cups a day is associated with lower rates of heart disease, neurological disorders and liver disease.”