You need calcium for strong bones and teeth, but also for proper function of your muscles and nerves and for blood clotting. Although getting your calcium from food is best, some people do not eat enough calcium-rich foods to meet their daily calcium needs. In this case, you can take calcium supplements to make up the difference. However, some supplements are easier for your body to absorb than others.
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. A new type of calcium supplement, called amorphous calcium carbonate is even better absorbed, according to a study published in the "Journal of Bone and Mineral Research" in 2011. Supplements containing this form of calcium have come on to the market, reports ScienceDaily, allowing you to take a lower dose of calcium with a smaller chance of side effects.
Factors That Affect Absorption
Regardless of which type of supplement you take, a number of factors either increase or decrease calcium absorption. Choose a supplement with the United States Pharmacopeia symbol and make sure you have sufficient vitamin D intake to increase absorption of your calcium supplements. Take doses of 500 milligrams or less at a time, and take your supplement with milk and with a meal. Tannins in tea, fiber, oxalic acid, phytates, excessive phosphorus or magnesium intake and certain medications can decrease calcium absorption.
For children up to 6 months old, the recommended dietary allowance for calcium is 200 milligrams per day; for children between 7 and 12 months, 260 milligrams; for children between 1 and 3 -- 700 milligrams; for children between 4 and 8 -- 1,000 milligrams; and for children between 9 and 18 -- 1,300 milligrams. Adults 19 to 50 years old need 1,000 milligrams per day; women over 50 -- 1,200 milligrams; men between 51 and 70 -- 1,000 milligrams; and men over 70 -- 1,200 milligrams.
Side Effects and Safety
Some people experience side effects when taking calcium supplements, including bloating, constipation and gas. Excess calcium intake can increase your risk for kidney stones, constipation, kidney problems, and deficiencies in iron and zinc. Calcium can interact with antibiotics, anticonvulasants, diuretics and other medications, so speak with your doctor before taking supplements.