Drinking water warmer than room temperature is a practice found in many health and cultural traditions worldwide. This simple change in temperature impacts several physiological systems in the body. While all water intake contributes to hydration, the thermal energy of warm water interacts uniquely with the human body, influencing processes from circulation to digestion.
How the Body Reacts to Warm Water Ingestion
The immediate response to swallowing warm water involves the body’s internal temperature regulation and circulatory system. Warm water acts as a vasodilator, prompting the widening of blood vessels throughout the body, including those in the digestive tract and near the skin’s surface. This dilation allows blood to flow more easily, which can improve circulation.
The increased blood flow to the skin can lead to minor heat loss, helping keep the body’s core temperature stable. Warm water is also theorized to be absorbed more readily than ice-cold water. Cold water requires the body to expend energy to warm it up before full absorption, a step minimized with warm water intake.
The difference in temperature can also influence the sympathetic nervous system, which controls involuntary body functions. While cold water ingestion has been associated with a decrease in heart rate, warm water does not produce these noticeable cardiovascular changes. Warm water is closer to the body’s core temperature, resulting in a less pronounced physiological adjustment than cold water.
Specific Effects on Digestion and Respiration
The warmth of the water can have a soothing and stimulating effect on the muscles lining the gastrointestinal tract. Warm water helps relax these smooth muscles, which encourages peristalsis, the wave-like contractions that move food through the digestive system. This stimulation can make the process of digestion feel smoother and more comfortable.
Drinking warm water is often suggested as a remedy for mild constipation, as it helps hydrate the stool and promotes intestinal movement. Ingestion of warm fluid can assist in breaking down food particles, aiding the digestive system in processing meals more efficiently. Some studies note that warm water may have favorable effects on intestinal movements and gas expulsion.
Beyond the digestive system, warm water can provide temporary relief for symptoms related to the upper respiratory tract. The heat and gentle steam produced can help loosen and thin mucus in the nasal passages and chest. This action can temporarily soothe a sore throat and reduce congestion, making it easier to breathe.
The soothing effect on the mucous membranes in the throat and sinuses is similar to that experienced with other hot beverages. A warm drink may offer quicker and more lasting relief from symptoms like a runny nose, coughing, and sore throat compared to room temperature drinks. The warmth helps lubricate the throat, reducing irritation caused by mucus buildup.
Safety Thresholds and Preventing Scalding
While drinking warm water offers certain benefits, it is crucial to avoid temperatures that can cause thermal injury to the mouth and esophagus. The primary risk of drinking hot water is scalding the delicate mucosal linings. To prevent burns, the optimal temperature range recommended for hot beverages is between 130 and 160 degrees Fahrenheit (54 to 71 degrees Celsius).
Temperatures significantly above this range can rapidly cause damage. Water that is too hot can burn the sensitive tissues of the tongue, mouth, and throat almost instantly. Chronic ingestion of excessively hot liquids may pose a risk of long-term damage to the lining of the esophagus.
For safety, individuals should always test the temperature before consuming any hot liquid. Setting household water heaters to a temperature that prevents scalding at the tap, no higher than 120 degrees Fahrenheit (49 degrees Celsius), helps reduce the risk of accidental thermal injury. This lower temperature is advised for tap water, but beverages can be safely consumed slightly warmer if proper caution is taken.