The Importance of Calcium for Bone Health
Calcium is crucial for maintaining bone health throughout our lives. In Australia, the recommended dietary intake (RDI) for calcium is 1000mg for adults and 1300mg for women after menopause and people over 70. This is similar to US recommendations but lower than the UK’s NICE guidelines, which recommend 700mg.
Calcium Supplementation and Bone Health
The topic of calcium supplementation and its impact on bone density and osteoporosis is complex and somewhat controversial. Studies on calcium supplementation have shown mixed results. While some data supports a reduction in fractures, many studies do not. Several studies indicate a slight increase in bone density (around 1%) but no significant reduction in fracture risk.
Issues with Calcium Supplementation Studies
There are several issues with the available data on calcium supplementation, making it difficult to make broad recommendations:
- Many studies combine calcium supplements with vitamin D rather than examining calcium alone.
- Multiple studies are short in duration, resulting in a low absolute number of fractures, making it hard to show statistical significance.
- Studies often do not select participants with low dietary calcium.
- There may be poor compliance with taking the supplements.
Recommendations from Osteoporosis Foundations
Major osteoporosis foundations provide somewhat vague advice, suggesting that you “may benefit” from calcium supplements or that your doctor “may recommend” them if you are not meeting the RDI. They generally advise a maximum of 500-600mg/day of calcium supplements.
Safety of Calcium Supplements
Calcium supplements are known to slightly increase the risk of kidney stones. There is also a contentious issue regarding the risk of heart attack and stroke. Observational studies and some randomized controlled trials (RCTs) show a small increased risk of coronary artery disease and strokes with calcium supplements, particularly with doses over 1000mg or in people with diabetes. It is challenging to disentangle association from causation in these cases.
My Practice and Recommendations
In my practice, I always aim for the RDI of calcium through food. I occasionally recommend supplementation if someone has osteoporosis and their daily dietary calcium intake is less than 700-800mg, or if their bone density is declining despite treatment. I usually advise taking calcium citrate 300mg, as it is better absorbed and requires a lower dose.
Always talk to your doctor to determine if a calcium supplement is right for you, especially if you have any underlying health conditions.