[adrian_b]

That drinking something bitter prepares your body in any way, is interesting speculation, which may be true or not. I am not aware of any evidence in favor of this idea. It seems more likely that the only purpose of the bitter taste is to make you spit the food before swallowing it. The sour taste has the same purpose for most animals. Humans and their relatives are among the few who enjoy sour things, and even some bitter things.

On the other hand, for the sweet taste we know that receptors exist not only in the mouth, but also in the intestine, where also the starch from the food would be already digested into glucose or maltose, so it would be sensed as sweet, and where the sweetness receptors do not cause any conscious sensation, so they must have another purpose.

The role of the sweetness receptors from the intestine is not known yet, because short-term studies could not determine it. However, they must have some effects, though those might appear only after longer times of periodic stimulation.

[arghwhat]

> I am not aware of any evidence in favor of this idea. It seems more likely that the only purpose of the bitter taste is to make you spit the food before swallowing it.

That would not explain why the stomach delays opening in response to bitter in the mouth, similar to preparing for protein digestion on glutamate detection.

But of course, we don't exactly have a spec sheet to work with here, so all we can do is theorize on why a particular trait might have evolved...