CalAsorb, supplies calcium in the citrate form which is believed to be one of the most easily absorbed compounds of calcium, due in part to its high solubility compared to other calcium compounds. Three tablets provide a full 800mg of calcium which is the recommended daily allowance, plus we have added 6ug vitamin D3. It is well established that many people's diets provide insufficient supplies of calcium and that low calcium intakes can contribute to the rate at which bone mass declines with age. The Department of Health recommends that women should have an intake of up to 1200mg of calcium per day, a level that is hard to achieve through diet alone, especially if the diet contains little dairy produce. Calcium supplements provide a convenient way to increase the intake of calcium, and have been shown to help slow the inevitable loss of bone mass that occurs as we get older. The body needs vitamin D to absorb calcium. Without enough vitamin D, one can't form enough of the hormone calcitriol (known as the "active vitamin D"). This in turn leads to insufficient calcium absorption from the diet.