Supplement Absorption. The two most recommended forms of calcium are calcium citrate and calcium carbonate. Calcium citrate is slightly better absorbed because it doesn't require much stomach acid for absorption, but calcium carbonate is well absorbed when taken with food.upplement Absorption. The two most recommended forms of calcium are calcium citrate and calcium carbonate. Calcium citrate is slightly better absorbed because it doesn't require much stomach acid for absorption, but calcium carbonate is well absorbed when taken with food.