> As to soda, I struggle to imagine a soda that has any amount of juice worth taking into account…
It's not just the juice. The acidity level of your stomach affects absorption of many drugs - some are absorbed faster in an acidic environment and some are absorbed slower, which means drinking even Coca Cola (pH: 2.5) with your medication could potentially have the effect of negating your medication or increasing the effective dosage substantially, depending on the drug.