How much calcium should we all consume? The answer to this question keeps changing.  In the 90s, there was a big push for supplemental calcium for people with or at risk of osteoporosis.  The recommendation was to take at least 1500mg of elemental calcium every day. This equates to roughly 5 cups of milk (1 cup of 150mL = ~ 300mg calcium).  Most people didn’t (and still don’t) drink 5 cups of milk everyday nor did they consume enough calcium from other dietary sources.  So the niche of calcium supplementation was born! There were so many different options of calcium supplements – from natural sources of oyster shell, to effervescent tablets that could be dissolved in liquid, to chewable chocolate or strawberry flavoured calcium – all of which aimed to encourage calcium intake.

Now fast forwarding to few years ago, we have learned that taking too much calcium can increase the risk of calcification of the blood vessels leading to cardiovascular events such as myocardial infarction (heart attack)[1].  The medical community was shocked by such news but had to react.  After all, supplemental calcium has not demonstrated any convincing benefits to reduce fall or fracture risks. So in 2010, Osteoporosis Canada has updated its recommendation of calcium intake to 1200mg/day which can either be from dietary source or supplemental.

More recently, the EPIC study further confirmed the potential risk with calcium supplement but established taking calcium from dietary sources is safe[2]. Osteoporosis Canada has released another guideline for long term care facilities last fall. It continues to recommend a total of 1200mg/day of calcium intake but specifies that it should be from dietary sources as much as possible. For people at very high risk for falls, it may be reasonable to take no more than 500mg/day of calcium in the form of supplement.

Over the span of 2 decades, we have made some significant changes to our calcium recommendations. Not only is calcium supplement not highly regarded anymore, there are many considerations that clinicians may not realize:

  • Only a maximum of 500mg of calcium can be absorbed at a time, so prescribing calcium 1000mg once daily is no different than prescribing calcium 500mg once daily. With the latest evidence, there is really no reason to prescribe more than 500mg/day.
  • Calcium supplement can bind to medications such as levothyroxine (a thyroid supplement, fluoroquinolones (a class of antibiotic for treating infections) and iron supplement, decreasing the body’s ability to absorb the medications to render their effects. The best way to manage this interaction is to space out the administration times so they are taken at different times over the course of a day.  This is complicated for the patients so they may not take them correctly or not take them at all.
  • Those calcium pills are hard to swallow, can be nauseous and constipating, not to mention that it can lead to kidney stones when taken in excess.

If a patient is in fact at risk for falls and fractures, I would much prefer a dose of sunshine with Vitamin D and investing in some quality exercise routines along with encouraging calcium intake from dietary sources.  And if a patient indeed meets diagnostic criteria for osteoporosis, treating with qualified drugs such as bisphosphates or denosumab would be the way to go.

I am ready to ditch the calcium pill, are you?

[1] Bolland M., Barber P., Doughty R., Mason B., Horne A., Ames R., et al. . (2008) Vascular events in healthy older women receiving calcium supplementation: randomised controlled trial. BMJ 336(7638): 262–266

[2] Li K, Kaaks R, Linseisen J, et al. Associations of dietary calcium intake and calcium supplementation with myocardial infarction and stroke risk and overall cardiovascular mortality in the Heidelberg cohort of the European Prospective Investigation into Cancer and Nutrition study (EPIC-Heidelberg) Heart. 2012;98(12):920–5