Many of you are aware that strontium, a mineral closely related to calcium, has been used in humans in several forms as a bone-building agent. In Europe, the compound strontium ranelate (a salt that uses ranelic acid) is available as a drug (Protos/Protelos). In the US, FDA has not approved strontium ranelate as a drug, but various forms of strontium are available as dietary supplements (most commonly strontium citrate). Our goal here is not to discuss the widely published efficacy of strontium ranelate, but simply to update you on some interesting and recent studies concerning the related compound strontium citrate; in particular, two studies which address the ability of strontium citrate to deliver similar levels of strontium to bones (I have included links to a number of very remarkable recent studies about strontium ranelate at the end for you to follow if interested).
The first is an animal study (in rats) that is similar to many of the studies which first showed (and are still showing) the various ways in which strontium modifies bone structure and prevents bone fractures. What makes this study interesting for our discussion is that it was a head- to-head study between the citrate and ranelate versions of strontium. Rats were given an equivalent amount of strontium (either as citrate or ranelate) or placebo starting at 19 weeks and followed for another 8 weeks. Researchers could measure the amount of strontium incorporated into the bones of the rats using a custom X-Ray fluorescence spectrometer. Post-mortem analysis of several bones was also performed using the same techniques.
What they found was very simple and straight-forward, strontium provided from citrate salts incorporated into bones just as well (or maybe even better) than the strontium provided from ranelate. As it turns out, they had to re-adjust the data because the strontium content of the strontium citrate was higher than they originally figured- and when they made the adjustment, the two were virtually identical (see figure below). Even though it was predicted (by us and others) that the citrate form is essentially equivalent in its ability to deliver strontium to bone tissue- this study goes a long way to confirm this fact, albeit in an animal model.
The second study is actually a very unique case-study of an osteoporotic women who decided to take strontium citrate and allow researchers at McMaster’s University to follow her bone strontium levels for nearly 3 years (this was an earlier report from the some of the same researchers who performed the rat study above). The subject was 68 years of age and had no history of supplementing strontium in any form prior to the study. She began supplementing with strontium citrate pills which provided 340 mg of elemental strontium (as citrate) per pill; taking 2 per day for a total of 680 mg of strontium per day. Using X-Ray fluorescence, researchers measured the changes in strontium levels in her finger and ankle bones. Not only did her bone strontium levels statistically increase after just 5 days, but it continued to increase until it reached a plateau after 1 year (at least in the finger). However, in the ankle, strontium was continuing to accumulate even after 2.5 years of strontium intake. In both cases, the majority of the increase occurs in the first 3-6 months.
The constraints of such a case-report being used for a wide conclusion are obvious, although there has never been a reason to believe that strontium as a citrate salt would perform in a manner different than strontium as a ranelate salt in this, or any, subject. Even so, we take this limited data for what it is worth. Beyond that, the X-ray fluorescence technique described in this paper could open up more opportunities to study the dynamics of strontium accumulation in bone, as this diagnostic technique results in much less radiation than a traditional DEXA scan. [Email communication with the author of the study does confirm they have repeated this analysis in many more subjects and this data will be published in the near future].
Of course, we would like to see more data generated, perhaps a clinical trial similar to those done with strontium ranelate performed using strontium citrate. Finding someone to fund such a trial while no one holds a patent for strontium citrate (or even an exclusive) is daunting- since such a trial would need to have a large number of subjects and be at least 2-3 years long. I do know of a researcher who is willing to do the study if the money is available…any takers?
A full whitepaper on the role of strontium as a bone-building agent will be available in the Whitepapers section soon. Also see The Standard Vol. 6 No. 2 for a discussion of other related nutrients that can be used to support osteoporosis.
- Strontium ranelate–a promising therapeutic principle in osteoporosis. J Trace Elem Med Biol. 2012 Jun;26(2-3):153-6
- A large prospective European cohort study of patients treated with strontium ranelate and followed up over 3 years. Rheumatol Int. 2013 Mar 2
- Cost-effectiveness of strontium ranelate in the treatment of male osteoporosis. Osteoporos Int. 2013 Feb 1. [Epub ahead of print]
- Healing of subtrochanteric atypical fractures after strontium ranelate treatment. Clin Cases Miner Bone Metab. 2012 Sep;9(3):166-9
- Efficacy and safety of strontium ranelate in the treatment of knee osteoarthritis: results of a double-blind, randomised placebo-controlled trial. Ann Rheum Dis. 2013 Feb;72(2):179-86.