Until recently, doctors often prescribed calcium supplements for patients at high risk of osteoporosis, however, new evidence questions their role. We investigate why.
What are calcium supplements prescribed for?
For years, calcium supplements have been prescribed with bone density medications to help strengthen the bones of people at high risk of the bone-weakening disease osteoporosis, particularly for people who don’t get much calcium from their diets.
What form do calcium supplements come in?
Calcium supplements most commonly come as tablets, often in an effervescent form that fizzes when dropped in water. Some also contain other supplements, such as magnesium or vitamin C, but the version prescribed by your doctor will be plain calcium carbonate. There is no current evidence that adding magnesium or vitamin C makes them any more effective.
What risks or side effects do calcium supplements have?
In a recent meta-analysis of 11 studies involving 12,000 patients, Professor Ian Reid from the University of Auckland and his team were surprised to find that regular use of calcium supplements was seen to be associated with an increased heart attack risk of as much as 30%, with a smaller increase in the risk of strokes.
It is still unknown whether it the high levels of calcium that caused the problem or the fact that it was taken in tablet form.
“There was no evidence that having a high dietary calcium intake is bad for your heart,” says Dr Reid. “If anything, it is good. Therefore, we think it is the supplements themselves that might be the problem.”
He suggests that the concentrated slug of calcium boosts the levels of calcium in the blood for 4 to 6 hours to such a degree that it speeds the build-up of calcium plaque in the arteries, leading to increased narrowing of your arteries.
This study has raised a number of questions for the scientific community and further research is needed.
Is there a safer alternative?
As a result of Drs Reid and Bolland’s findings, many doctors are now recommending that your best line of defence against osteoporosis is to get plenty of calcium in your everyday diet.
- Foods that are high in calcium include milk, yoghurt, cheese and other dairy products, salmon, sardines, tofu, broccoli, spinach, peas, sesame seeds, almonds, seaweed and calcium-fortified foods and drinks.
- Daily exposure to the sun helps your body to produce vitamin D, which it needs to put that calcium to work building strong bones.
- Regular weight-bearing exercise will also help build strong bones.
Although calcium supplements are available over the counter, as with other dietary supplements, you should seek advice from your doctor before taking them.
Calcium supplements New Zealand Formulary Patient Information
- Bolland MJ, Avenell A, Baron JA, Grey A, MacLennan GS, Gamble GD, et al. Effect of calcium supplements on risk of myocardial infarction and cardiovascular events: meta-analysis. BMJ 2010;341:c3691
- Reid, I. Bolland, MJ. Editorials: Controversies in Family Medicine – Does Widespread Calcium Supplementation Pose Cardiovascular Risk? Yes: The Potential Risk Is a Concern. Am Fam Physician. 2013 Feb 1;87(3):online. Full article
- Bhattacharya, RK. Editorials: Controversies in Family Medicine - Does Widespread Calcium Supplementation Pose Cardiovascular Risk? No: Concerns Are Unwarranted. Am Fam Physician. 2013 Feb 1;87(3):online. Full article