Asked August 20, 2016, 11:43 PM EDT
Multnomah County Oregon
Thank you for your question on calcium supplements. As you would expect, there are many variables on how well a supplement is absorbed such as the type of supplement, the form of supplement, the amount of supplement, if taken with food or without, if Vit D is available, an individual's ability to absorb the supplement.
Here are a few general guidelines for taking calcium supplements:
1) Take with food for better absorption
2) Take in small doses throughout day (500 mg or less at a time)
3) Ensure adequate Vit D is available
I did not find a comparison of absorption rates of calcium carbonate versus calcium gluconate. Some people prefer Calcium citrate because it is still well absorbed even without food and may be better absorbed by older adults that have less digestive enzymes. Some people prefer Calcium carbonate because it is less expensive. Calcium gluconate has only 9% elemental calcium (the amount of calcium that can actually be absorbed) so it takes a larger volume to get the same amount of calcium.
So the bottom line is that any of these supplements could work but its important to find one that you will take on a regular basis. The RDA for calcium is 1000 mg and increases with age.
Whenever possible choose foods rich in calcium such as: Dairy products, dark green leafy vegetables, fish with edible soft bones, calcium-fortified foods and beverages.