Dr Bernstein, indicates your Calcium supplement should be taken with Vitamin D, magnesium and manganese. Have you found a supplement that contains all 4?
I have found that in most cases, special combination products are markedly more expensive and don’t always give enough of the vitamins and minerals. OS-Cal Ultra has all four, and is about $15/120 tabs, but only has 200 IUs of vit D and 600 mg of calcium and I believe the levels of magnesium and managese are no better than you would get in a good multivitamin. Costco has a much better version “Calcium Citrate with D” at $7/300 with 800 IUs of D, 500 mg of calcium, 80 mg of magnesium and 1mg of manganese.
What I usually do is choose a good multivitamin like Costco premium multi, which has 400 IU vitD, 165 mg calcium, 50 mg magnesium (13%), and 7.5 mg of manganese (375%) and then I supplement from there. I take additional vitamin D and sometimes magnesium. With my diet, I get plenty of calcium.