A related question (Does drinking warm or hot water aid in digestion?) asks about the effects of hot water on digestion. I recently came across an article that claimed a much larger set of benefits. Are there any non-digestive effects of drinking hot water? Or, are there non-digestive effects that are caused by the digestive effects of hot water?
Effects of temperature of beverages on health
1. Temperature of beverages does not affect intestinal absorption. Consumption of cold beverages may reduce less body temperature during exercise.
A study by Tan PM et. al. in 2015 found that beverage temperature does not affect intestinal absorption. However, it was also noted that ingestion of cold beverages leads to reduction of less body temperature during exercise.
Temperature of drinks does not seem to have an effect on the rate of gastric emptying and intestinal absorption. The ingestion of cold drinks can reduce body core temperature before exercise but less so during exercise.
2. Drinking hot beverages triggers sweat response which may help in production of very small changes in body temperature.
A study by Bain R et. al. in 2012 found that drinking hot water triggered a sweat response that compensated for the heat of the drink. The opposite response was produced by drinking cold drinks, with a reduction in sweat cancelling out the cooling power of the drink.
CONCLUSION: Under conditions permitting full sweat evaporation, body heat storage is lower with warm water ingestion, likely because of disproportionate modulations in sweat output arising from warm-sensitive thermosensors in the esophagus/stomach. Local temperature changes of the rectum following fluid ingestion exacerbate the previously identified error of thermometric heat storage estimations.**
3. Drinking cool beverages increase fluid consumption and hydration during physical activity.
A study by Burdon et. al. in 2012 evaluated the effect of beverage temperature on fluid intake during exercise and investigated the influence of beverage temperature on palatability. It found that cool beverages may influence consumption and hydration during exercise.
CONCLUSION: Cool beverage temperatures (<22 °C) significantly increased fluid palatability, fluid consumption, and hydration during exercise vs. control (≥22 -°C).
The University of Nebraska also suggests cool water as the best fluid replacement during sports events.