Ask the experts
I've noticed that you recommend antacids for heartburn, but you do not mention Tums or Rolaids. Aren't these good antacids? In addition to their acid-neutralizing effects, aren't they also good as sources of calcium?
Gastroenterologists generally do not prescribe calcium carbonate-containing antacids such as Tums or Rolaids. The reason for this is a phenomenon called acid-rebound. Calcium carbonate-containing antacids, unlike other over-the-counter antacids, stimulate the release of gastrin from the distal stomach and duodenum.
Gastrin is the hormone primarily responsible for the stimulation of acid secretion by the stomach. After the direct acid-neutralizing effects of the calcium carbonate are exhausted, the secretion of acid rebounds due to the release of gastrin, and there is an overproduction of acid. Theoretically, this is not good for the stomach and duodenum.
Acid rebound has not been shown to be clinically important, that is, it has not been shown that treatment with calcium carbonate is less safe than treatment with antacids not containing calcium carbonate. Nevertheless, the phenomenon of acid rebound has been well-documented and is potentially harmful. In practice, the occasional use of calcium carbonate-containing antacids probably is not harmful. One advantage of calcium carbonate-containing antacids is their low cost. Another is the additional calcium that they provide, though there are other sources of calcium. Could calcium carbonate-containing antacids be bad for people who take them for calcium supplementation? It's unknown, no one has raised the issue, and there are no reports of problems.