I've pretty much always understood that minerals can dilute the stomach's acids so not good with food digestion going on.
However when taken on a completely empty stomach they can sometimes cause nausea so I usually take about 45 minutes after a meal so there might be some remaining digesting going on but the minerals don't totally stop the process.
Also I try never to take right before a meal, waiting two hours after taking them before eating anything to give the stomach acid time to get back "up to speed."
I'm guessing that the only possible exception to this may be citric acid forms but I'm not sure.
Possibly, someone will give a more educated answer than I did.