Saturday, October 20, 2012

Strontium for Osteoporosis?

Is it advisable to take high doses of strontium?...This is a complex question.
There has been quite a lot of research showing that strontium increases bone density and reduces fractures both in the spine (up to 40%) and the hip while continuing to preserve bone quality. At least this is what we are seeing with the osteoporosis medication, strontium ranelate (Protelos or Protos). Protelos is available in over 70 countries around the world, but the FDA has not approved it for sale in the United States. Nonetheless, interest in strontium (other than in prescription ranelate) remains high. I've had many patients ask me what I think about taking supplemental strontium salts (which contain significantly higher amounts of strontium than are found in our supplements (OsteoMineralBoost and OsteoMineralWhey). Below are my thoughts on this topic.


Strontium:
Strontium is quite an interesting metalic element. It is a trace mineral found naturally in foods such as shellfish, whole grains, lettuce, spinach, kale, root vegetables, Brazil nuts, and dairy. Other than radioactive strontium and strontium chromate, strontium is not toxic and there are no major adverse effects linked to taking any of the readily available supplemental forms of strontium salts such as citrate, gluconate, lactate, or carbonate.

Strontium is silver-white in color and very chemically reactive. When exposed to air it turns yellow and if you grind it up into a powder it will ignite spontaneously, bursting into bright red flames--thus its use in fireworks. Because strontium is so reactive in air and water, it is only found in nature bound to other elements.

Strontium's biological role in the body remains somewhat of a mystery. Chemically similar to calcium, strontium is able to replace calcium in certain biological settings. For example, in neural synaptic clefts strontium can be involved in conduction pathways just as calcium is. And, in the mineralization phase of bone remodeling, strontium can replace calcium in the formation of new hydroxyapatite crystals. Where else in the body, and to what extent, strontium replaces calcium atoms is not known.

Strontium Ranelate:
Strontium effects bones in two ways: it stimulates osteoblasts to form bone and it inhibits osteoclasts from resorbing bone. The result is an increase both in density and in actual bone tissue (i.e. not just harder bone but more of it). This unique dual action has driven great interest in the use of strontium for the treatment of osteoporosis. But there are two major problems, at least with strontium ranelate. The first is that 50% of the improvement seen in DXA T-scores after using strontium ranelate is not "real." Because the strontium atom is almost twice as heavy (38 on the atomic chart) as calcium (20
on the atomic chart), when strontium is deposited into bone it just "looks" more dense than calcium on DXA exams. The second problem is that the FDA has not approved strontium ranelate. The adverse effects of this medication include VTEs (vein thromboembolisms) and the rare but serious and sometimes life-threatening drug reaction/rash with eosinophilia systemic syndrome (DRESS).

Strontium Salts:
It is important to understand that the adverse effects noted above are NOT connected with strontium salts. In addition, any ability of strontium ranelate to reduce fractures cannot simply be transferred to strontium salts. We just do not know for sure if strontium salts help to reduce fractures; there has been very little research using these forms of strontium. They may improve bone density, but like strontium ranelate, 50% of this may be "artifact" and the other 50% may or may not actually help reduce fractures.

Another difficulty I have with high dose strontium salts is that I can't wrap my brain around flooding the body with a trace mineral especially when we don't actually know what this mineral does. There are only about 0.3 grams of strontium in the body whereas there are over 1,000 grams of calcium. (The highest concentration of both of these minerals occurs in bone and the teeth.) With strontium being able to step into the biological shoes of calcium and with its action appearing to be anabolic in bone (similar to Forteo), we need to approach its use with some reserve.

The Case for Bisphosphonates:
In general, when patients are at high risk for fracture they should consider using a bisphosphonate medication or teriperitide (Forteo), not high doses of strontium salts. Not only are the resulting increases in bone density true reflections of change, there have been bucket loads of research to confirm that they reduce fractures. (Note: My position on bisphosphonates is that they should only be prescribed in the short term and only when necessary to reduce immediate fracture risk.) Using short courses of these medications can be absolutely vital to patients who are fracturing and, if tolerated, they should certainly be chosen over strontium salts. Even doctors in Europe and Canada typically only prescribe strontium ranelate as a second choice to bisphosphonates which are intolerable to some patients.

The Research Continues:
Research continues to mount for the benefits of strontium for reducing fracture risk. Unfortunately, research on strontium salts will always lag behind that of strontium ranelate due to the inability to patent salts. I found the following three abstracts from the recent American Society of Bone and Mineral Research 2012 Annual Meeting quite interesting:
  • In the first abstract, researchers from China studied a special group of goats found in a village in the Yunnan Province. These goats have bright red bones and teeth and are therefore named "red-boned goats." The researchers found these goats to have 3 times the normal content of strontium in their bones and significantly lower amounts of calcium. They also found twice the level of two enzymes related to osteoblastic bone formation. Analysis of the soil where the goats grazed showed 2-4 fold higher levels of strontium and calcium concentration. The researchers concluded "Environmental strontium consumption could alter bone metabolism significantly. Higher Sr+ [strontium] consumption had an anabolic action on bone."1
  • In the second abstract, researchers from Italy analyzed the reaction of osteoblasts and calcified nodules (from the fat-derived stem cells of a 45 year old female). They found that at low doses the strontium increased mineralization and at higher doses it increased osteoblast activity. They concluded that strontium "could play a role in the therapy of bone disorders also promoting osteogenic cells proliferation and differentiation."2
  • In the third abstract, researchers from China and the University of California, Davis, again studied the red-boned goats. What they found was that strontium reduced bone resorption by reducing RANKL, a molecule that signals osteoclastic activity.3

It is clear that strontium has an anabolic effect on bone. This can be beneficial, but to what extent does this become a risk? When something interferes with bone's normal uptake of calcium and has an anabolic effect similar to Forteo,  I get concerned. For now, I will continue to recommend strontium as trace minerals to everyone. Strontium is absolutely necessary for normal bone formation and for health in general and our OsteoMineralBoost and OsteoMineralWhey are both excellent sources of trace strontium.  I recommend them highly. As for higher doses of strontium salts, I consider their use on an individual basis.

1. SA0285. Xu Z., et al. Higher strontium consumption is anabolic in goats.

2. MO0227. Ciuffi S., et al. Effect of strontium ion on in-vitro proliferation and osteogenic differentiation of PA20-h5, a clonal mesenchymal stem cell line derived from subcutaneous adipose tissue.

3. MO0243. Lin Q., et al. Comparative analysis of osetoclast differentiation from red-boned and common goats.


Website design and website development by Confluent Forms LLC, Easthampton MA