Calcium, together with vitamin D and weight-bearing activity, helps build and maintain strong bones. General targets are around 700 to 1000 mg a day for many adults, with higher amounts often advised for older people, postmenopausal women and others at higher risk of osteoporosis. Food sources include milk, cheese, yoghurt, fortified plant milks, tofu set with calcium, leafy green vegetables and tinned sardines or salmon with the bones.
Getting calcium from food is generally preferred over supplements, which are usually reserved for people who cannot meet their needs through diet or who have specific bone conditions. Vitamin D is important because it helps you absorb calcium.
Taking high-dose calcium supplements unnecessarily can cause constipation, kidney stones and may interact with some medicines, and there has been debate about heart effects of large supplemental doses. Calcium also reduces absorption of certain medicines, so timing matters. Ask a doctor or pharmacist before starting calcium supplements, especially if you have kidney problems or take other medication.