Dampening dangers throughout your digestive tract
It might seem like your taste buds are there to add pleasure to your life, letting you enjoy a sweet chocolate, tangy nectarine or perfectly bitter coffee. The pleasure of tasting is actually a gift from our brains to keep us focused on finding the right things, because a lot of what our taste receptors are doing is actually trying to keep us safe. That’s true of the receptors in our mouths, and especially true for the receptors in our stomachs and even our colons. As fun as it might be to taste a great cup of coffee a second time in our belly, receptors throughout our digestive tract are keeping watch to ensure we’re not being poisoned.
Even with so many examples of tasty, healthy and life-affirming bitter foods, bitterness is actually a flavor animals have evolved to be wary of thanks to poisonous compounds like solanine. Things that are too bitter can be fairly revolting, and children usually have a higher sensitivity to such flavors than adults, which makes sense considering the larger threat of poison to a smaller body. Of course, in measured doses, some would-be poisons aren’t really a problem the way they were intended to be, and that’s where our stomach’s taste receptors come in.
Portioning versus purging
The taste receptors in our stomachs don’t trigger a sensation of taste of course, but they’re mechanically the same as what’s on your tongue. When the right molecule comes along, it can fit into the receptor on the surface of your cell, activating it. In your mouth, this activation sends a signal to your brain so the stimulation can be processed as taste. In your stomach, it’s automatically used to control the amount of bitter substances you may be about to digest. After a larger meal, too many bitter activations may tell your stomach to slow down and hold food longer. This way, you’ll be less likely to digest and metabolize a dangerous amount of a toxin at once, instead doling out small and presumably manageable amounts over time. It also means you won’t feel hungry too soon.
If you’ve somehow ingested too much of a bitter, poisonous substance, your colon is also looking out for you. In fact, the receptors in your colon can trigger a sort of retroactive poison-control, telling your gut to fill with water to flush your digestive tract. Instead of holding onto potential threats before they get out of hand like your stomach, your colon uses diarrhea to flush things out. Clearly, you want your stomach’s receptors to be good at their job to avoid such emergency measures.
Source: You Have Taste Receptors in Your Colon. Here's Why. by Esther Inglis-Arkell, iO9