Coffee may be off the hook

By Corin Kelly
Wednesday, 22 June, 2016

There is no conclusive evidence for a carcinogenic effect of drinking coffee, according to an international Working Group of 23 scientists convened by the International Agency for Research on Cancer (IARC), the cancer agency of the World Health Organization (WHO).

A summary of the final evaluations into the carcinogenicity of drinking coffee, maté, and very hot beverages. is published today in The Lancet Oncology, and the detailed assessments will be published as Volume 116 of the IARC Monographs.

The experts did find that drinking very hot beverages probably causes cancer of the oesophagus in humans. No conclusive evidence was found for drinking maté at temperatures that are not very hot.

“These results suggest that drinking very hot beverages is one probable cause of oesophageal cancer and

that it is the temperature, rather than the drinks themselves, that appears to be responsible,” says Dr

Christopher Wild, IARC Director.

Very hot beverages

Drinking very hot beverages was classified as probably carcinogenic to humans (Group 2A).

This was based on limited evidence from epidemiological studies that showed positive associations

between cancer of the oesophagus and drinking very hot beverages. Studies in places such as China, the

Islamic Republic of Iran, Turkey, and South America, where tea or maté is traditionally drunk very hot (at about 70 °C), found that the risk of oesophageal cancer increased with the temperature at which the

beverage was drunk.

In experiments involving animals, there was also limited evidence for the carcinogenicity of very hot water. “Smoking and alcohol drinking are major causes of oesophageal cancer, particularly in many high-income countries,” stresses Dr Wild. “However, the majority of oesophageal cancers occur 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.”