Sipping hot water

 

You said:

My grandmother (actually great grandmother but as she raised my mother we dropped the "great") would always have a cup of relatively hot water nearby, and sipped on it all day. She made no health claim: "Oh, I like it." Still, obviously it did her no harm. I see now because of promotion on the internet of Chinese health ideas, it's become a thing in the States. We have no simple way to heat water here: the cooking is done with propane in another house, so I pretty much drink things either cold out of the fridge or at room temperature. First thing on waking and ten minutes before cold coffee, I drink roughly a glass of water from a covered container bedside (that I also use to moisten my mouth if I wake up at night with a dry mouth). I would guess warm or room temperature water gets into the system slightly faster, but can imagine no other difference. Info?

ChatGPT said:

Your intuition is basically right, and the physiology here is refreshingly mundane.

Water absorption itself happens in the small intestine, not the stomach, and the intestine is very efficient at absorbing plain water regardless of temperature. What temperature mainly affects is gastric emptying—how quickly fluid leaves the stomach and enters the intestine. Very cold liquids can slow gastric emptying a little; very warm liquids can speed it a little. But the effect is small and short-lived. For normal hydration in a resting person, the difference amounts to minutes, not hours, and has no practical consequence for health.

Once absorbed, the body very quickly equilibrates the water to core temperature. The energy required to warm cold water is trivial—on the order of a few calories per glass—so there is no meaningful metabolic advantage either way. Claims that warm water “detoxifies,” “activates digestion,” or “flushes toxins” are best understood as cultural metaphors rather than physiological mechanisms. Your kidneys do the detoxifying; water temperature does not change that.

Where temperature can matter is comfort and symptoms. Warm or hot water can feel soothing, can transiently relax the esophagus, and may help some people with mild dyspepsia or esophageal spasm. Cold liquids can feel refreshing but may provoke discomfort in people prone to reflux or esophageal sensitivity. These are individual effects, not general rules.

One real caution—though it doesn’t apply to your grandmother’s “relatively hot” sipping—is that habitually very hot beverages (near-scalding) are associated with increased esophageal cancer risk in some populations. The mechanism appears to be chronic thermal injury, not the beverage itself. Sipping warm water well below scalding is not an issue.

Given your situation, what you’re doing already makes excellent sense. Drinking room-temperature water on waking is gentle, effective hydration. Using it overnight for dry mouth is sensible, especially given antihistamine use. Warm water would not confer a health advantage beyond subjective comfort, and cold water is not harmful unless it causes you discomfort.

So the bottom line is almost disappointingly simple:
Hydration matters; temperature mostly doesn’t. Drink water the way you enjoy it and can reliably do every day—your grandmother’s reasoning was probably the wisest of all: “Oh, I like it.”

You said:

I've always thought the benefit to her of the practice was emotional.

ChatGPT said:

I think that’s a very perceptive read—and quite possibly the whole story.

A cup of warm (or even just “not cold”) water within reach, sipped slowly, is a tiny, repeatable ritual. It creates continuity through the day, a sense of being tended to, even if one is doing the tending oneself. That sort of low-level emotional regulation doesn’t announce itself as “health,” but it often shows up as health over decades.

There’s also a bodily quietness to it. Warmth in the mouth and throat is calming; slow sipping enforces pauses; the cup itself becomes a familiar object. All of that nudges the nervous system toward the parasympathetic—without anyone needing to know or name such a thing. Your grandmother didn’t need a theory; she had a practice.

And crucially, it was non-demanding. No rules, no virtue signaling, no “you must.” Just preference. Practices like that are sustainable precisely because they aren’t instrumentalized. The internet versions you’re seeing now tend to strip that away and replace it with claims, which paradoxically makes them less healthy.

So yes—emotional benefit is not only plausible, it’s likely the primary benefit. The body follows the mind more often than we like to admit, especially over a lifetime.