With all due respect, there's a reason people use Tums: they have acid indigestion. It's effective not
because it has calcium in it, but because it presents a carbonate group - which reacts with gastric HCl to generate CaCl2 and, eventually, CO2+H2O. This is not pseudoscience, it's extremely
basic (ha!) acid/base chemistry and ADME.
Your comparison to milk is inappropriate, as calcium isn't the active agent in Tums. However, the fat content in milk can influence the absorption of other drugs
- though not likely kratom
alkaloids, as they've more polar moieties than most psychoactive
I agree that the potentiation won't be profound - but the efficacy of any antacid in potentiating any alkaloid
would be a function of the acidity found in the stomach, which ranges between individuals. So, it won't have a titratable and predictable effect - but to suggest that the effect will effectively be nil is categorically inaccurate.