The type of Calcium that the body can best absorb is calcium carbonate, I think.  I use a brand from my health
food store called Nature's Way that includes powdered Calcium and Magnesium in a gel capsule which I think
makes for quick absorption .  The Magnesium is also good for your muscles.  My Doctor recommended
something called Caltrate which I think you can get in most supermarkets.
 I think people with Hashimoto's may have malabsorption problems which means that you're not getting the
benefit of the vitamins and minerals in the food you eat.  I know when I use a non-iodine containing vitamin
supplement, extra C, B complex, E, Calcium and Magnesium, I feel better. I have also started ending my day with
a cup of Stinging Nettle tea sweetened with FOS and this also seems to be helping.  I got the Nettle tea from the
Health Food Store and the FOS from a General Nutrition Store.  FOS is a natural sweetener with actibacipholus
(?).   Good for the tummy.