Hello Kfbers, we have got a very important topic today on Know Your Own Health.
Coffee was classified as a possible cause of cancer in 1991, but the International Agency for Research on Cancer (IARC), which is part of WHO, has now reconsidered the evidence.
It carried out a detailed review of the many studies published on the subject and found that coffee drinkers have no reason to worry.
IARC also investigated the herbal drink mate, also known as chimarrão or cimarrón, which is widely consumed in South America and drinks like tea consumed at high temperatures in Central Asia, China and Japan.
Mate is drunk at temperatures of more than 650C (1490F), often through a metal straw. A temperature of 650C is quite hot.
The experts found that mate was not a cause of cancer, but they believe the temperature at which it is drunk probably is – and that other very hot liquids (around 650C or above) - including water, coffee, tea and other beverages, could also be linked to oesophageal cancer.
Oesophageal cancer is the eighth most common cause of cancer worldwide and one of the main causes of cancer death, with around 400,000 deaths recorded in 2012.
IARC produces what it calls monographs on the causes of cancer, which use classifications from group one, where the link is definite, as with smoking; to group four, where there is probably no link.
The new monograph classifies hot drinks as group 2A, meaning they are “probably carcinogenic to humans”. Coffee and mate served cold are in group three, which means there is insufficient evidence to believe they cause cancer. IARC’s conclusions are published in the Lancet Oncology journal.
Studies in animals have shown that very hot water can promote the growth of tumours. IARC’s scientist, Dr Dana Loomis, in a comment said: “It appears that there is thermal injury from exposure to hot liquids that is capable of leading to cancer of the oesophagus.”
Those who enjoy hot tea in Europe and the United States probably do not need to worry, Loomis said. “It is important to recognise that hot drinks that were studied for the basis of this classification are perhaps a bit different from tea or coffee as consumed (in other parts of the world) – 650C is quite hot.”
In European countries, coffee and tea are usually drunk at below 600C and milk is often added, which cools it. Tea in Iran and mate in South America are often drunk at 700C.
The scientists found an “inverse relationship” between drinking coffee and certain types of cancer. Liver cancer dropped by 15 per cent for each cup of coffee drunk, while in breast cancer and endometrial -or womb - cancer studies suggest there were fewer incidences among people who drank coffee than those who did not.
The WHO’s official spokesman in Geneva, Gregory Hartl, said the evaluation of hot drinks was based on limited evidence in humans and animals, and that more research was needed.
He stated: “We say: be prudent, let hot drinks cool down. The WHO’s advice was to “not consume foods or drinks when they are at a very hot, scalding hot temperature.”