Q. How much calcium can I absorb at one time from a supplement?
A. Bess Dawson-Hughes, MD, director of Tufts' HNRCA Bone Metabolism Laboratory, says: "For maximal absorption of calcium from supplements, no more than 500 to 600 milligrams (mg) of elemental calcium should be taken as a single dose. For the few people who require more than 500 to 600 mg of calcium in supplement form, the dose should be split. For best absorption, calcium carbonate should be taken with meals. Calcium citrate may be taken anytime."
The Recommended Dietary Allowance (RDA) for calcium is 1,000 mg for men and 1,200 mg for women ages 51 to 70; for adults age 71 and older, the RDA is 1,200 mg. Dairy products and many fortified foods are rich in calcium. An 8-ounce serving of cow’s milk or calcium-fortified soymilk and 6 ounces yogurt each have 300 mg calcium, so make sure you actually need a supplement.