Yes, timing matters. Three factors determine when you should take calcium supplements:

• Type of calcium. Check the label to find out what kind of calcium the supplement contains. Calcium citrate can be taken with or without food. Calcium carbonate should be taken with food. Stomach acid produced while eating helps your body absorb calcium carbonate.
• Total daily dose. Calcium is best absorbed when it's taken in smaller doses (typically less than 600 milligrams at one time). If you take 1,000 mg of calcium a day, split it into two or more doses over the day.
• Medications and supplements. Calcium supplements can interact with many prescription medicines, including antibiotics, bisphosphonates and high blood pressure medications. Ask your doctor or pharmacist about possible interactions between calcium supplements and your medications.

It's also a good idea to take your calcium supplements at a different time from your multivitamin or an iron-rich meal. Calcium can affect how your body absorbs iron, zinc and magnesium.

If you still aren't sure about the best time to take calcium supplements, check with your doctor or pharmacist for guidance.