Back in February, 2013 this blog looked at the positive association between calcium intake and the risk of all cause death rates and cardiovascular disease in women. Older people have historically been encouraged to obtain their calcium from dietary sources instead of supplements. A recent systematic review of randomized controlled trials as well as observational studies by Mark Bolland et al. concluded that there is no association with dietary intake of calcium and risk of fracture. Moreover, these authors found that the association between calcium supplements and fracture risk is similarly weak.
Interestingly, there are only two randomized controlled studies of dietary calcium intake and fractures. Contrary to RCT evidence, there are 50 reports from 44 cohort studies on the relationship. In adults older than 50, for most studies (> 75%) , no relationship between dietary calcium intake, including milk or dairy sources, and fractures of the hip, spine or forearm could be confirmed.
In randomized studies, the degree of total fracture reduction associated with supplemental calcium was statistically significant with an 11% reduction (95% CI, 0.81, 0.96). However, the clinical importance of this reduction is uncertain. When examining this relationship with specific fracture types (hip or forearm fractures), a statistically significant reduction could not be demonstrated. One trial1 in frail elderly women in residential care with low dietary calcium and low Vitamin D levels, did show decreased fracture risk (but 6 other similar trials that did not.)
So, most of the studies were observational and suffer from the inherent risk of bias. It seems to me, the blogger, that there should be some level of calcium intake that is necessary. Where too much is unhealthy, zero intake would seem to be unhealthy as well (reductio ad absurdum). Nonetheless, we clinicians are caught calcium carbonate and a hard place again.
What’s a doctor to do? Well, it starts with our pediatrician and family physician colleagues. Put the calcium in during growth. Even after they stop growing taller kids continue to make more bone than they lose. Bone mass peaks somewhere between 18 and 25. Seek to dispel parental concerns (and self-diagnoses) of lactose intolerance in those less at risk (more common in the elderly, Blacks, Asians, Hispanic, and Native Americans but much less common in Northern Europeans). Being products of the Kool-Aid generation, we missed out on this little piece of advice and are paying for it now.
- Chapuy MC, Pamphile R, Paris E, et.al Combined calcium and vitamin D3 supplementation in elderly women: Confirmation of reversal of secondary hyperparathyroidsism and hip fracture risk : The Decalyos II study. Osteroporosis Int 2002;13:257-64.