I tell what i know, till someone more informed reply:
For what i know, if nitrite is exposed to air, dissolves his volatility compount, making it nitrate.
Also reacting to stomach acids, converts it to nitrate.
The conversion cannot be 100% i mean, not all the nitrite can become instantly nitrate so there can be always a percentace in a nitrate that originally was nitrite.
The nitrite contains the toxic compound that converts hemoglobin in mathemoglobin, that is unable to syntesize oxygen and gives hypoxia. Mostly by a chemicall process of oxydization, nitrate insteal can be poisenous acting like some sort of fertilizer.
Nitrate is not able to oxydize, because of a different chemical reaction, instead can be able to bring all the other wasting syntoms due the body accumulating chemicals that dont know how to deal with, and trying to rid of them as soon as possible, causing lot of disconfort.
This if is nitrate 100% (sold as nitrate) as said before, if was originally nitrite i can retain a percentage of effectiveness but may lead to a longer journey.
This is what i read, but i am more into anatomy and less into chemical, so i expect some more precise info by somone else.
