Glutamate's first stop is also its terminus; umami can stand in for salt only as replacement.
Full mechanism, in text
How MSG helps you use less salt
1 · The first stop is also where most of it ends
The small-intestinal epithelium burns passing glutamate on the spot as fuel, so the first stop for glutamate is also where most of it ends.Glutamate's first stop is the small-intestinal epithelium, and that is also where most of it ends. The mucosa renews extremely fast and is among the most energy-hungry tissues in the body; glutamate passing through the lumen is one of its main fuels. It burns that glutamate on the spot.
2 · The little that leaks still meets the liver
The little glutamate that leaks past the gut wall is used by the liver in turn, so after these two checkpoints only a small remainder reaches the systemic circulation.The little that leaks past the gut wall into the portal vein has a next stop: the liver, used for amino-acid conversion and energy. What reaches the systemic circulation is the small remainder after those two checkpoints. Eat , blood glutamate spikes barely holds under a normal meal.
3 · The barrier mainly pumps it out, not in
Even if blood rose a little, the directional gate is still there: blood–brain-barrier transporters mainly move glutamate from brain into blood, not the other way.The excitotoxin-into-the-brain road cannot even get past the gut-wall link.
4 · Umami can stand in for some salt — replace, do not add
Umami can fill the hollow left by cutting salt, but contains sodium too, so the tool works only as replacement for some salt, not addition.Salt and umami are two devices; only after they join do you judge whether the dish has enough flavor. The hollow after cutting salt can be filled by umami. itself contains sodium. Keep salting as usual and add MSG on top, and total sodium only goes up. The tool works as replacement, not addition.