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Uncovering carbonation’s powerful ability to cool and refresh

Most spring water in Europe is hard water containing carbonic acid, so people prefer to drink carbonated water with meals. More health-conscious Japanese have also been turning to carbonated water recently. Though there has been some research on how carbonated water functions to alleviate digestive problems and other gastrointestinal symptoms, few studies have targeted the changes that carbonated water triggers in our bodies. We studied the physiological effects of drinking carbonated water and found that it can effectively regulate body temperature.

What does carbonated water do to our bodies?

Drinking carbonated water creates an immediate and intense feeling in the mouth. Our study looked at the effects of carbonated water on the body—both in that first instant and after swallowing. Specifically, we measured eardrum temperature (core body temperature), toe temperature (skin temperature at the extremities), and heart rate (autonomic nervous system function) to track physiological changes during both stages of intake.

Experimental method

We conducted an experiment on 13 females of similar age, height, and physical condition. Using carbonated water and still water without carbonic acid, both kept at 15℃, we compared the results under the four conditions shown on the right and checked whether they were the effects of sensory stimulation or the effects of actually swallowing the water.

Measurement of body response (including temperature)

(1) Intake of still water (2) Intake of carbonated water (3) Only taking still water in the mouth (without swallowing) (4) Only taking carbonated water in the mouth (without swallowing)

In the experiment, we measured the body temperature and heart rate of the subjects at rest for 20 minutes, and then had them drink 150 ml of water in 5 minutes. Then, we measured the body temperature and heart rate for 40 minutes, and during that time, took an electrogastrogram. We collected data on subjective symptoms at 10-minute intervals before and after drinking the water.


How do these cooling effects work?

We used a sophisticated thermosensor to measure both core (eardrum) and extremity (toe) temperature, and then took the average values to compare the four conditions across thirteen subjects. We found that carbonated water had a significant effect on decreased extremity temperature over still water. More importantly, the effects were apparent the minute the carbonation hit the mouth. Heart rate measurements taken to examine autonomous nervous system function also revealed a temporary increase just with mouth stimulation—an increase that was significant compared to the other three conditions. These results suggest that mouth stimulation from carbonated water signals the brain and the autonomic nervous system, effectively decreasing extremity temperature while increasing heart rate.

Both cold carbonated water and cold still water lower the body temperature when swallowed. However, we found that the sensory stimulation caused by carbonated water in the mouth produces additional effects that decrease body temperature. Drinking carbonated water in addition to wearing cooler clothes can thus help alleviate discomfort during the hot summer months—which is great news for office energy conservation efforts!

 Making everyday life more comfortable

Through our careful study of changes in the human body and other groundbreaking research, Suntory has been able to provide customers with beverages that offer diverse value options to support better everyday living. Our recent study revealed that simply stimulating the mouth with carbonation has the physiological effect of regulating body temperature, making drinking carbonated water a powerful and efficient strategy for cooling the body and making everyday life more enjoyable. Suntory research goes back to basics and asks fundamental questions about what beverages affect us and how. Uncovering the hidden functions and mechanisms that solve these riddles allows us to continually offer innovative new beverages that make life more delightful and satisfying for everyone.

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