What’s so special about drinking room-temperature water?

Water is vital for our body. It helps flush out waste products from the blood and maintain kidney function (1). Increasing our water intake improves our energy levels, feeling of wakefulness and clarity of mind whereas reducing our water intake has a negative effect on our mood and activity level (2).

But does it matter what the temperature of our drinking water is?

Ayurveda tells us to drink water that is warm or at room temperature. Cold water is considered harmful as it extinguishes the Agni, the body’s ability to digest, absorb and assimilate. Ultimately, this can lead to a build-up of undigested food, causing a weakened immune defence because the body has accumulated waste.

The stomach contains different types of receptors including mechanoreceptors, chemoreceptors and also thermoreceptors. These are activated when we eat and drink. So, it makes sense to assume that meal and drink temperature would affect digestion and the gut.

Here are some ways that drink temperature can impact the body:

Gut motility

The lining of our stomach and intestines is made of smooth muscle which moves and contracts to help digestion and to move food along the gut. This is known as peristalsis or gut motility.

Several studies have shown that room-temperature or warm water has the effect of improving intestinal movements (3, 4, 5). Cold or hot water have been shown to reduce gut motility (5). These studies have been carried out with people at different ages and stages. One study found that after surgery, intestinal movements improved quicker when drinking warm water (3). This has useful implications for the hospital setting. Constipation after surgery is common because of inactivity, stress, side effects of pain medication, and dehydration, so getting the gut moving again is important.

One explanation of why this happens is that our body is busy using its energy to keep our core temperature in check, so other activities such as digestion are put on pause.

Blood flow

Cold water has an effect on our nervous system too, constricting our blood vessels. This is seen in patients who have low blood pressure – when drinking cold water, their blood pressure rises quicker (pressor response) than it does when drinking warm water (6). This vasoconstriction can lead to poor blood supply to certain areas of the body such as the digestive system but also the head. One study showed how in some people, migraines headaches were brought on by drinking cold water (7).

Comfort

Room-temperature water may be more comfortable to drink too. Studies have shown drinking cold water can lead to a greater sensation of discomfort in people with IBS (8) and can increase gastric pressure and discomfort in people with functional dyspepsia epigastric pain syndrome as well as in healthy adults (9).

After consuming cold water, people with oesophageal achalasia (problem with lower oesophageal sphincter not relaxing) experienced more discomfort than when drinking warm water (10). The cold water prolonged the contraction of the oesophagus and increased the pressure of the oesophageal sphincter (opening into the stomach).

Easing congestion

Outside of the digestive system, drinking cold water has been shown to increase nasal congestion whereas drinking warm water loosens it (11). Whether this is the effect of the steam created by warm drinks being inhaled is not known. Either way, the next time you have a cold, go for a warm drink instead of a cold one to clear the mucous.

So, modern scientific studies mirror old Ayurvedic teachings. Warm and room-temperature water has benefits for our body. It’s very common these days to be served ice with our drinks when out or to grab a cold drink from the fridge but this can slow down our digestion and leave us feeling uncomfortable. Try drinking warm or room-temperature water and see if you notice a difference in your digestion and general comfort.

References:

(1) Nakamura et al. (2020 Effect of increased daily water intake and hydration on health in Japanese adults. Nutrients, 12(4)

(2) Pross et al. (2014) Effects of changes in water intake on mood of high and low drinkers. Plos One 9(4)

(3) Caliskan et al. (2016) The effect of warm water intake on bowel movements in the early postoperative stage of patients having undergone laparoscopic cholecystectomy: a randomised controlled trial. Gastroenterology Nursing, 39 (5).

(4) Fujihira et al. (2020) The effects of water temperature on gastric motility and energy intake in healthy young men. European Journal of Nutrition, 59(1)

(5) Sun et al. (1995) Effect of drink temperature on antropyloroduodenal motility and gastric electrical activity in humans. Gut, 37

(6) Kubota et al. (2022) The pressor response to the drinking of cold water and cold carbonated water in health younger and older adults. Frontiers in Neurology, 10

(7) Mattson (2001) Headache caused by drinking cold water is common and related to active migraine. Cephalalgia: An International Journal of Headache, 21(3)

(8) Zuo et al. (2006) Visceral hypersensitivity following cold water intake in subjects with irritable bowel syndrome. Hournal of Gastroenterology, 41(4)

(9) Rui-Feng et al. (2012) Temperature can influence gastric accommodation and sinsitivity in functional dyspepsia with epigastric pain syndrome. Digestive Diseases & Sciences (58(9)

(10) Ren et al. (2012) Response of esophagus to high and low temperatures in patients with achalasia. Journal of Neurogastroenterology & Motility, 18(4).

(11) Saketkhoo et al. (1978) Effects of drinking hot water, cold water and chicken soup of nasal mucus velocity and nasal airflow resistance. Chest (74(4)