Calcium carbonate is the cheapest, but it consumes gastric acid, potentially causing bloating and indigestion.
Calcium gluconate is sweet but contains less calcium; it is suitable for children.
Calcium citrate is slightly more expensive; calcium bound to citric acid does not combine with oxalic acid to form insoluble calcium oxalate precipitates, allowing direct excretion from the intestines—thus offering higher absorption than calcium carbonate.
Chelated calcium is the most expensive; calcium is bound to amino acids and absorbed directly through the intestines.
Supportive Nutrients:
Vitamin D3: Enhances calcium absorption (D3 can also be synthesized naturally through regular sun exposure).
Vitamin K2: Promotes calcium transport to bones.