Why are there two different amounts of calcium on the TUMS labels?
Because TUMS has a dual usage — as both an antacid and as a calcium supplement — the label includes the actual amount of calcium carbonate (for those who use the product as an antacid) and the elemental calcium (the amount of calcium that your body is actually able to use). For those who use TUMS as a calcium supplement, the amount of calcium under Supplement Facts is the amount of elemental calcium contained in the calcium carbonate.