I havenr seen studies but it was actually the legion supplement companys research director who cautioned me on NAC, even though their multivitamin i believe contained some. And yes he did mention dose. But I wonder if nac becomes more risky for people who already have leaky gut or slow metabolism?It is useful too break up mucus because it breaks the di-sulfide bonds in the mucus, allowing it to thin out, hence more easily flowing to be removed.
I would like to see studies on the stomach assumption, I have the feeling that dose plays a big part in that assertion. My stomach has felt better since using NAC. It may have drawbacks, but then everything does, so if something mitigates a problem that nets worse outcomes, the harm is less than the cure, if there is even a harm.