Calcium is only one component necessary to build and/or maintain healthy bones; you also need vitamins C, D, and K; the minerals boron, potassium, and magnesium; and, adequate protein and resistance exercise — all the more reason to eat a variety of foods and move your body.

Daily calcium needs are listed as follows:

Age (years)	Adequate Intake [AI] of elemental calcium (mg/day)
1 - 3	500
4 - 8	800
9 - 18	1,300
19 - 30	1,000
31 - 50	1,000
51 - 70	1,200
> 70	1,200

When your calcium supplement is well absorbed, your body can easily use it. For best absorption, most calcium supplements should be taken with food. Calcium citrate is an exception; it can be taken with or without food.

It is best to spread out the calcium you consume from diet and/or supplements throughout the day. In fact, for best absorption, it is recommended to consume 500mg of calcium or less at one time.

When to take calcium supplements depends on the type. Calcium carbonate needs to be taken with meals, as the acidity of the stomach is greater when food is being digested. This acidic environment allows for its absorption. Calcium citrate, however, is absorbed more efficiently than calcium carbonate on an empty stomach, so it needs to be taken between meals.