I'm also curious about absorption issues. I know my body doesn't absorb calcium like it should. What kind of absorption issues do you have? Maybe your experiences could help me understand myself.
Vitamin D is needed for calcium absorption, most US Americans are deficient in Vitamin D. Talk to your doctor about a supplement and maybe getting the test to see if you are deficient.
Because of Cardio Vascular Disease, Diabetes, history of smoking and not being a sun person, I take D3 5000 iu a day to keep my levels up.