The Best Calcium Supplement Choice for Bones

 A: A great calcium supplement contains 600mg of calcium, plus 200 IU to 300 IU of vitamin D (which delivers the calcium to your bones) and 200mg of magnesium (to help balance the effects of calcium on nerve function). Plus, the pill needs to be a size you can swallow twice a day. That’s right: You’ll need to take two pills a day to get the recommended 1,000mg to 1,600mg of calcium (depending on your individual calcium needs), because you can only absorb 600mg of calcium at a time. And that 1,000mg to 1,600mg needs to be actual calcium, not calcium combined with citrate or carbonate—if you choose supplements with citrate or carbonate, check the label to make sure they contain the proper amount of calcium. It’s also important to avoid supplements that have iron in them, because iron inhibits calcium’s absorption. (If you’re taking iron for anemia, take the iron two hours before or after taking calcium.) Also, calcium needs an acid environment for absorption, so getting your calcium in an antacid may not be optimal. —Cardiac surgeon and star of The Dr. Oz Show, Dr. Mehmet Oz