Many have to wait for their coffee to cool before they are able to drink it.
Many have to wait for their coffee to cool before they are able to drink it.

Can't drink hot coffee? Then you have cat tongue

In Japan, this is a very common phenomenon. In Norway, we have no word for it.

Some seem to be able to down scalding hot coffee, while others have to wait until it has cooled down a bit.

In Norway we do not have a name for this phenomenon, but they do in Japan:

猫舌 (ねこじた) nekojita – cat tongue. This word refers to having a ‘heat-sensitive tongue’ and is used to describe people who cannot tolerate hot food and drinks.

Several studies have been conducted to determine what temperature coffee, tea and other hot drinks people tolerate.

13-degree difference

German researchers investigated the pain threshold of coffee temperature.

Pain threshold is the point where it starts to hurt.

The researchers gave 87 people a cup of coffee. Participants checked if the coffee was too cold, just right, or too hot for them. Then they were given new cups of increasingly hot coffee.

Participants stopped when they felt the coffee was burning their tongues.

There were large differences in the temperature at which participants reached their pain threshold. The first cup of coffee that everyone received was 58°C. At that temperature, some felt that their tongue was burning. While one participant did not feel a burning sensation until the coffee was 71°C.

Okay for one, painful for another

“There is a huge difference in how much pain people feel and can endure,” says Christopher Nielsen. He is a researcher at the Norwegian Institute of Public Health and does research on, amongst other things, sensitivity to pain.

Some people feel pain quickly, and can be characterised as having a low pain threshold, while others are able to tolerate more before they feel pain.

“We are all different. Something that is not close to hurting one person can be unbearably painful for others,” Nielsen explains.

There are also differences in the type of pain we tolerate poorly or well.

Christopher Nielsen studies pain.
Christopher Nielsen studies pain.

Different types of pain

“People can generally only tolerate small amounts of pain from heat, but substantially more from pressure or cold,” Nielsen tells sciencenorway.no.

Although much research has been done on pain, especially in connection with injuries and diseases, not everything has been fully explored.

Nielsen does not know if we have different pain thresholds on different areas around the body. That is, if people who are sensitive to heat in their mouths, also tolerate heat poorly on the rest of the body.

What is certain, however, is that the mouth is particularly sensitive to heat.

Thin mucous membrane

We have several pain receptors in our mouths. These are cells that sense and report pain to the brain.

The thin mucous membrane in our mouth does not protect us as well from heat as our skin does. The mucous membrane acts like skin where the outer layer is gone, according to Lars Arendt-Nielsen, pain researcher at Aalborg University in Denmark, in an interview with Videnskab.dk (link in Norwegian).

A freshly brewed coffee cup is so hot that the liquid should actually burn all mouths. Some researchers put sensors in the mouths of coffee drinkers to check what is happening inside. The coffee is quickly distributed throughout the mouth and swallowed. There is not enough time for it to damage the tissue with its heat, these researchers believe.

However, if the drink is too hot, you may get small burns down your throat. In addition, regular consumption of very hot drinks can increase the risk of esophageal cancer, according to the German study.

Those who drink coffee that is a little less hot may therefore have some health benefits.

The concept of cat tongues in the sense of heat sensitivity has also spread to China, according to Nathan Edwin Hopson at the University of Bergen.
The concept of cat tongues in the sense of heat sensitivity has also spread to China, according to Nathan Edwin Hopson at the University of Bergen.

Cat tongues are very common

Not tolerating hot drinks is very common in Japan. These people can be said to have a cat tongue.

“Nekojita is a very common word in the Japanese language,” says Nathan Edwin Hopson. He is an associate professor of Japanese at the University of Bergen.

The word comes from the cat's aversion to hot food.

“I had never heard of the phenomenon before I came to Japan,” says Hopson, who is himself American.

Having a cat tongue is neither negatively nor positively charged. It's simply something you are, according to Hopson.

A Japanese website for weather forecasts conducted a survey amongst its readers. It was winter and the season for hot stews and soups. This is a difficult season for those with cat tongues, according to the website. They wanted to find out how many of the readers were nekojita.

More than 10,000 readers responded.

Half had cat tongues

47 per cent stated that they had cat tongues. It was most common amongst people in their 20s.

The Japanese website also offers an explanation for why so many people are heat-sensitive: Those with cat tongues stick out their tongues when they eat. Thus, the tip of the tongue touches the hot food.

It is difficult to determine whether this explanation is correct, as there is little research available.

For those who make a living from drinking coffee, high temperatures are important.

Ole-Kristian Elvenes from Wilfa has worked with coffee machines for several decades.
Ole-Kristian Elvenes from Wilfa has worked with coffee machines for several decades.

Take small sips

The temperature of the coffee is important for it to taste good, according to Ole-Kristian Elvenes, district manager in Wilfa, who sells coffee makers.

“The water in the funnel should be from 92 to 96°C when it hits the filter. This makes the coffee taste its best,” he tells sciencenorway.no.

The coffee jug keeps the coffee warm at 80 to 85°C, although this is still too hot for most mouths.

“When we pour the coffee into a mug, it cools quickly and falls below 75°C,” says Elvenes. He himself drinks coffee at 70°C, which is several degrees above the average pain threshold in the German study.

“I have drunk so many litres of coffee over so many years that I have become used to it,” Elvenes says.

His advice to those with cat tongues is to wait a bit, blow a little on the coffee and take small sips. Then the coffee quickly becomes drinkable for everyone.

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Translated by Alette Bjordal Gjellesvik.

Read the Norwegian version of this article on forskning.no

References:

Dirler et al. What Temperature of Coffee Exceeds the Pain Threshold? Pilot Study of a Sensory Analysis Method as Basis for Cancer Risk Assessment, Foods, 2018.

Lee et al. ‘Drinking hot coffee: Why doesn’t it burn the mouth?’ Journal of Sensory Studies, 2007. Abstract.

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