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Drinking enough water is vital to health and good bodily functioning. However, some research suggests that the temperature of water when a person drinks it is also important. According to the Indian traditions of Ayurvedic medicine, cold water can cause an imbalance to the body and slow down the digestive process.
The body has a core temperature of around 98.6°F and Ayurvedic practitioners reason that the body needs to expend additional energy to restore this temperature after drinking cold water.
In the Ayurvedic tradition, cold water can dampen “the fire,” or Agni, which fuels all the systems in the body and is essential to health. Ayurvedic practitioners also believe that warm or hot water helps to ease digestion. In Western medicine, there is little scientific evidence to suggest that cold water is bad for the body or digestion. Drinking plenty of water can help the body flush out toxins, aid digestion, and prevent constipation.
A small study from 2013 investigated the effects of drinking water at different temperatures in six people who were dehydrated, following mild exercise, in a hot and humid chamber. The researchers found that changing the water temperature affected the sweating response of the participants and how much water they drank.
The optimal water temperature in the study was 16°C (60.8°F), which is the temperature of cool tap water because the participants drank more water and sweated less. The researchers concluded that drinking water at 16°C may be the best temperature for rehydration in dehydrated athletes.
Some research suggests that people with conditions that affect the esophagus, or food pipe, such as achalasia, should avoid drinking cold water. Achalasia is a rare condition that can make swallowing food and drink difficult. A 2012 study found that drinking cold water worsened symptoms in people with achalasia. However, when participants drank hot water, it helped soothe and relax the food pipe, making food and drink easier to swallow.
One 2001 study involving 669 women suggests that drinking cold water may cause headaches in some people. The researchers reported that 7.6 percent of participants experienced a headache after drinking 150 milliliters of ice-cold water through a straw. They also found that participants with active migraine were twice as likely to get a headache after drinking cold water as those who had never had a migraine.
Some people claim that consuming cold drinks and foods can cause a sore throat or cold. However, there is no scientific evidence to support this claim.