Seems we not only detect sweet, sour, salt and bitter, but we have receptors for a fifth flavour, called "
umami".
This receptor picks up glutamates, and monosodium glutamate is added to food to tickle this particular tastebud.
This "taste" was proposed in 1908 and the existence of the receptors were confirmed in 2000.
This is not a Japanese phenomenon or anything strange, lobster meat, crabs, shrimp, parmesan cheese etc. are all rolling in MSG, though nothing more than the naturally occurring levels - reactions to Japanese food may be due to too much added MSG. If you use Soy sauce in cooking, it's because your body craves MSG.
It's as natural as water. But, like water, if you consume too much of it, you will probably die - or be very uncomfortable, in the very least.
MSG is not evil, though - the Japanese add it to their food because we've got receptors for it and crave it. They merely identified it and slapped a label on it.
