Your Own Health.
For the newbies, KFB Health Talk is a column where health–related
issues are examined to help us get more conscious about our health.World
Health Organisation (WHO) has cleared coffee of causing cancer, but a
detailed investigation has found that drinking hot liquids, including
hot coffee, may be linked to cancer of the oesophagus or gullet.
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
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.”