Get as much calcium as you can from food, which contains other nutrients that also boost bone health. Make up for shortfalls of calcium by taking supplements.
Take whatever supplement is most convenient and cheapest (usually calcium carbonate).
Take calcium with meals to enhance absorption (not necessary with calcium citrate), but no more than 500 milligrams at a time; any amount above that taken in a single dose is absorbed less efficiently.
You can also consume calcium-fortified foods to meet your daily calcium requirement. This can be especially useful if you have difficulty swallowing calcium pills, which are rather large. For example, calcium-fortified versions of orange juice, soymilk, tofu, breakfast cereal, bread, frozen waffles, oatmeal, energy bars, hot chocolate mix and even milk are available. Most calcium-fortified foods provide about 150 mg of calcium per 1⁄2 cup or 4 ounces.
Don’t exceed 1,000 to 1,200 milligrams of supplemental calcium a day, since more than that may increase the risk of certain kinds of kidney stones.
H2 blockers (such as Zantac and Pepcid) and proton pump inhibitors (such as Nexium and Prilosec) can decrease calcium absorption.