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Palca and Morning Edition Executive Producer Madhulika Sikka test if hot tea can cool you down on a hot day
Keep cool by drinking hot drinks?
“Trust me,” she said. “I’m Indian, I’m British. A billion Indians can’t be wrong. They drink hot tea in hot weather.”
“The hot drink somehow has an effect on your systemic cooling mechanisms, which exceeds its actual effect in terms of heating your body,”
There are all sorts of receptors in all sorts of nerves, but the nerves in the tongue have a lot of one particular receptor that responds to heat. It’s called the TRPV1 receptor, if anyone wants to know.
So when you eat or drink something hot, these receptors get that heat signal, and that tells the nerve to let the brain know what’s going on.
When the brain gets the message “It’s hot in here,” it turns on the mechanism we have to cool ourselves off: sweating.
Yes, the hot drink makes you hotter … but it does something else, too.
“The hot drink somehow has an effect on your systemic cooling mechanisms, which exceeds its actual effect in terms of heating your body,” says McNaughton.
One other interesting thing. These TRPV1 receptors respond to hot heat, but they also respond to chemicals in chili peppers, which is why chili peppers seem hot. “That’s probably why chili peppers are so popular in hot countries because they cause sweating and activate a whole raft of mechanisms which lower the temperature,” he says.
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Hot drinks should not be given to a hypothermic person anyway. It can be deadly. See page 220 of Bill Bryson’s book A Walk in The Woods or google ’16 danish sailors hypothermia’.
In WFA, we learned that hot drinks are not effective in warming up a hypothermic person. There just isn’t enough warmth there to make a meaningful change in the temperature of your body.
Let me find the back of an envelope…
An adult body has about 40 liters of water. Even a big cuppa is about 200ml, or 1/200th of the water in a body. I don’t know how hot tea is, but if I conveniently assume it is 20º warmer than 98.6º, it could raise your body temperature by 0.1º.
Sorry for switching between metric and English units, there.