Drinking water and the release of gastric acid

[PainterGuy]

Hi,

I think of a human body as an intelligent biological machine.

Could you please help me with the query below?

Question:
The stomach produces gastric acid and pepsinogen among other enzymes etc. When a glass of water is taken without any food, wow would the stomach react to water? Assume that the stomach was empty. Why wouldn't the presence of water in the stomach activate the release of gastric acid or pepsinogen? How would the stomach know that it doesn't need to release gastric acid or pepsinogen for water?

I think if it was milk instead of water, the stomach would release both gastric acid and pepsinogen.

 

[pinball1970]

Hi,

I think of a human body as an intelligent biological machine.

Could you please help me with the query below?

Question:
The stomach produces gastric acid and pepsinogen among other enzymes etc. When a glass of water is taken without any food, wow would the stomach react to water? Assume that the stomach was empty. Why wouldn't the presence of water in the stomach activate the release of gastric acid or pepsinogen? How would the stomach know that it doesn't need to release gastric acid or pepsinogen for water?

I think if it was milk instead of water, the stomach would release both gastric acid and pepsinogen.

https://en.wikipedia.org/wiki/Gastrin

There is a psychological side to this too think Pavlov and his dogs.
Taste smell stimulate secretions

 

[tech99]

I think water will raise the pH slightly which discourages pepsinogen production.

 

[jim mcnamara]

No. On an empty stomach, water is pretty much absorbed quickly. Digestive cues (the release of stomach acid) do not occur when water alone passes through the stomach to the small intestine. Water into an empty stomach is a straight, quick (~5 minutes) shot out the duodenum - into the small intestine. No digestive juices produced.

See: https://pubmed.ncbi.nlm.nih.gov/21997675/

 

[PainterGuy]

No. On an empty stomach, water is pretty much absorbed quickly. Digestive cues (the release of stomach acid) do not occur when water alone passes through the stomach to the small intestine. Water into an empty stomach is a straight, quick (~5 minutes) shot out the duodenum - into the small intestine. No digestive juices produced.

See: https://pubmed.ncbi.nlm.nih.gov/21997675/

Thank you!

But how would the stomach know that it doesn't need to release any gastric acid? Also what if one drinks milk instead of water? There are proteins in milk which need to be broken down.

The highly acidic environment in the stomach lumen degrades proteins (e.g., food). Peptide bonds, which comprise proteins, are labilized. The gastric chief cells of the stomach secrete enzymes for protein breakdown (inactive pepsinogen, and in infancy rennin). The low pH activates pepsinogen into the enzyme pepsin, which then aids digestion by breaking the amino acid bonds, a process called proteolysis.

Source: https://en.wikipedia.org/wiki/Gastric_acid

 

[jim mcnamara]

A simplified view: the "resting" pH of the stomach is sufficient to begin curdling milk. Curdles are solid enough to provide a sufficient physical cue to invoke addition of stomach enzymes.

FWIW - the stomach does not do all that much in the way of breakdown to the point where proteins are completely turned into amino acids. Or fats -> fatty acids. All that happens in the small + large intestine. Simple sugars like glucose and fructose are absorbed in your mouth, + stomach, + intestines. Starch -> glucose also happens largely in the small and large intestine.

Try this:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4956471/

FWIW: the fact that humans have been cooking food, a kind of predigestion, is a major evolutionary advantage. It reduces parasites in consumed food and breaks down complex food molecules to a more quickly digestible state. Liquids are no exception. So we get more nutritional "bang for a buck" by consuming cooked food...

 

[PainterGuy]

I really appreciate your help!

I'm sorry but I'm still trying to find the answer to the following. What factor(s) decide that how much gastric acid should be released and when it shouldn't be released at all?

As it has been said in the previous posts that for water gastric acid isn't released because water remains for short period of time in the stomach? Does the time factor also play a role?

A typical adult human stomach will secrete about 1.5 liters of gastric acid daily.

For example, when some cookies are consumed, the stomach is going to 'decide' how much gastric juice is needed or if needed at all? How does the stomach 'decide' it?

I'm sorry if you think that I'm going in circles.

 

[jim mcnamara]

Physical chunks of food. I don't think going into neurology will help much.

The stomach has a switch that says either:
"Churn, keep on processing"
"No churn, let it go into small intestine"

The switch works by sensing the resistance of the food to sloshing (churning)
Ex: water, koolaid, and de-pulped fruit juices all pass the slosh test quickly.
McDonald's burgers require extra liquid, enzymes, and time to break down the burger sufficiently to pass the slosh test.

Any liquid that thickens on entry fails the slosh test. Add a teaspoon of vinegar to milk, wait 30 seconds, emulate sloshing with a spoon.

This why - and it is important: The difference in energy used to process food is not trivial. So you win the evolutionary survival game with a more energy efficient system over somebody whose system wastes energy processing airballs because it cannot tell energy dense food from pure water.

 

[PainterGuy]

Thanks a lot! It was really helpful.

I think asking about the the switch would be little too much. :)

Anyway, from this discussion, I think that drinking too much water and/or cold water is not a good idea. If you drink too much water, it unnecessarily overloads the stomach. If the water is too cold, it makes the food chunks stick together and the resistance to sloshing increases, and this is unnecessary overload.