I'm not sure if this is "scientific evidence" but I accidentally bought calcium carbonate via on-line bariatric surgery website. After enjoying the scruptious chocolate covered caramel chews (3X a day) for about a month, I noticed my hip bones starting to give me trouble (I'm not a spring chicken -- 52, but now I'm the new 32 after my sleeve! But my bones are still 52!) I checked the ingredients to see if maybe they were the "wrong" calcium supplements-- lo and behold they were not calcium citrate! Boo hoo! I am now taking 12 Citricell minis a day (4 with each meal). They are smaller so go down easy, but boy I miss those caramel chews! (They also had 30 calories each, so I think they contributed to my "stall" at that time as well! My hip bone no longer aches, so I think that the calcium absorption may have been affected as well.) Hope this helps!