Is Oyster Shell a Good Source of Calcium?
The calcium compound in OS-CAL is oyster shell, and that means calcium carbonate. The absorption would be similar to other calcium carbonate sources. Calcium carbonate is best absorbed when there is stomach acid as this helps it get into solution — a necessary step before absorption. This means that absorption will be less in those with an inadequate output of gastric acid, (more common in the elderly), or those that take gastric acid blockers, such as Tagamet or Pepcid. OS-CAL is fine as a calcium/vitamin D source, but make sure that your diet contains all the other nutrients needed to make bone.
