Calcium and osteoporosis

Optimising calcium intake has been shown to achieve a small increase in bone mineral density (BMD), but data demonstrating a correlation between fracture risk and calcium intake alone are lacking. In most studies of treatments for osteoporosis, adequate calcium (and vitamin D) were entry requirements.

The Australian recommended daily intake of calcium is:

• 1300 mg in patients taking drug therapy for osteoporosis
• 1300 mg in women older than 50 years and men older than 70 years
• 1000 mg in women 50 years or younger and men 70 years or younger.

This intake should ideally be achieved from dietary sources. Encourage patients with a low dietary calcium intake to increase their intake of calcium-rich foods, rather than taking a supplement. Calcium supplements can cause bloating and constipation, and, in some studies, have been associated with a small increase in the risk of myocardial infarction (although this finding is not supported by other studies).

Dairy food is the main dietary source of calcium¹². Most milks contain approximately 1000 mg of calcium per litre. Concentrated low-fat and skim milks have a slightly higher calcium content. To achieve a daily intake of 1000 to 1300 mg of calcium, three servings of dairy products are recommended per day. Dairy foods are also a good source of protein, which may independently contribute to good bone health.

If a person’s daily calcium requirement cannot be met through dietary intake, an oral calcium supplement can be considered.

Calcium carbonate tablets are a reasonable first choice of supplement, based on their low cost and acceptable absorption in most people if taken after meals. Calcium citrate tablets are a reasonable alternative. Calcium citrate does not require gastric acidity for absorption, so may be better absorbed than calcium carbonate in people taking a proton pump inhibitor.

Limit the dose from a supplement to 500 to 600 mg of elemental calcium daily. Use:

The elemental calcium content of the supplement is the most important factor—there is no evidence that complex mineral preparations are more beneficial than simple preparations, and often they contain less elemental calcium.