In the sweltering heat of summer, the instinctual reach is often for an ice-cold drink. But in various parts of the world, like Bangladesh, India, Japan, and Saudi Arabia, a steaming cup of tea is the preferred choice, regardless of the weather. While this may seem counterintuitive, traditional Chinese medicine has long suggested that certain teas can offer a cooling effect, even when consumed hot. But is there any scientific basis to the claim that hot drinks can indeed cool you down on a hot day?

Peter McNaughton, a professor of pharmacology at King’s College London, affirms this paradoxical notion. His studies on thermoregulation reveal that a hot beverage can indeed trigger a drop in body temperature, at least under non-humid conditions. Initially, a hot drink will raise the body’s temperature, but the human body, like all warm-blooded creatures, is constantly working to maintain a stable internal temperature. McNaughton’s research found that hot drinks (and spicy foods) activate a receptor in our nerves called TRPV1, which sends a signal to the body to initiate cooling mechanisms – in other words, to start sweating. The process of sweating and subsequent evaporation, especially when aided by a breeze or a fan, helps dissipate heat, effectively cooling the body down.

Can Hot Drinks Really Cool You Down?

As temperatures rise, the instinctual reach is often for a cold beverage to quench the thirst and cool down. However, in many countries like Bangladesh, India, Japan and Saudi Arabia, hot tea is the beverage of choice, regardless of the weather. Traditional Chinese medicine even cites specific teas as having cooling properties when consumed hot. But can hot drinks genuinely cool you down during a hot day?

Scientific Backing for Counterintuitive Cooling

According to Peter McNaughton, a professor of pharmacology at King’s College London, hot drinks can indeed cool you down, but the context is crucial. McNaughton observes that while a hot beverage initially increases your body temperature, the human body adjusts to maintain a consistent internal temperature. Hot drinks activate a receptor in our nerves called TRPV1, signalling to the body to cool down, resulting in sweat. This sweat, when evaporated, takes heat with it, effectively cooling down the body.

However, this effect is most effective in dry heat. In high humidity, the air is already saturated with water vapor and can’t absorb as much from the skin, reducing the cooling effect of sweat.

The Importance of Hydration

Aside from the body’s physical response, another crucial way that hot drinks can keep people cool is by keeping us hydrated enough to sweat in the first place. Good hydration is essential for the body’s temperature regulation process. Cini Bhanu, a clinical research fellow at University College London, stresses the importance of hydration despite the temperature of the drink. For older people, whose ability to sense thirst decreases with age, regular drinking throughout the day is advised.

Debunking Misconceptions

Misconceptions around drink temperature and hydration were also found in a 2017 study by workplace heat consultant, Matt Brearley. He discovered that many outdoor workers prefer cold water but avoid it due to a belief that the cold will "shock" their systems, leading to less drinking overall and decreased hydration. Brearley recommends people stick to their preferences to maintain hydration but also emphasizes the need for other supports such as longer rest breaks and access to air conditioning.

Takeaways

The consumption of hot drinks can indeed lead to cooling effects, but it’s important to remember that it’s most effective in dry heat and less so in high humidity. However, the key to regulating body temperature is staying adequately hydrated, regardless of the temperature of the beverage consumed. So next time when the temperatures rise, feel free to enjoy that hot cup of tea. But remember, staying hydrated is the most important!