They removed antacids from the regimen due to a debate on their usefulness, some say that the high acidity in the stomach speeds up absorption while others say otherwise.
But, in my opinion, I think the low acidity actually interupts the absorption. If you don't have enough stomach acid, you can't digest food properly or absorb its nutrients, this is what happens for normal food and I'm convinced that it is the same for SN.
I think its best to keep antacids in the regimen but also its best to keep the protocol as simple as possible as too many medications can cause nausea.