Strontium is a heavy metal that is about twice as heavy and dense as calcium. The body “sees” strontium the same as calcium and substitutes it for calcium in bone. There is no natural role for strontium in human physiology or in the physiology of any animal. Strontium is a bone toxin because once it becomes concentrated in bone it remains there. The long-term impact of chronic strontium doping of the skeleton is not known. There is no known natural biologic mechanism for the body to remove strontium from the skeleton. The effect of retention of strontium and other heavy metals in the skeleton on human health and safety is not known and cannot be predicted from what we know now.
Strontium, because it is twice as heavy as calcium, causes the bone density to rise in people who ingest it since it replaces calcium in the skeleton. While the bone becomes denser on the DXA bone density test that does not mean the bone is stronger or less prone to fracture. This was a lesion learned in spades at the Mayo Clinic in the late 1980s.
Fluoride, a heavy metal deposited in bone had been recognized for years as a cause of increased bone density on X-ray. It was being hailed as a possible breakthrough therapy for osteoporosis. Fluoride is a heavy metal that is deposited in the skeleton and teeth. It is known to harden teeth and significantly lower the incidence of cavities. It was observed that people who drank well water naturally rich in fluoride had radiographically dense bones on plain X-ray in the early days of radiography. It was hoped that fluoride would be a good therapy for osteoporosis. It was used for this purpose in the pre-scientific days and the leading experts in the field were among its greatest proponents. In the late 1980s, fluoride was finally subjected to the double-blinded randomized placebo controlled trial that eliminated the bias of the investigators and the subjects. The subject’s bone density was measured by dual photon absorptiometry at the spine and hip, which was a newly developed technique that allowed the measurement of bone density with good accuracy and precision at the sites of greatest clinical interests, the lumbar spine and proximal femur. The results of the 4 years study stunned the osteoporosis world. The bone density rose 35% in the spine and 12% in the femoral neck in the fluoride treated patients but there was no significant decrease in spine fracture rates between the two groups. The fluoride treated patients had significantly more peripheral fractures and drug related side effects. What we learned from the fluoride study was that heavy metals like fluoride when deposited in bone increase the bone density but doing so does not in itself have any effect on fracture rates or bone quality.
The European FDA has registered a form of strontium for treatment of osteoporosis. The US FDA has not registered strontium for any medical use in America.
Algae-based calcium sold in the US contains strontium and other heavy metals including germanium and vanadium. The best-known strontium containing calcium supplement product is marketed as New Chapter Bone Strength. I recommend avoiding the use of all heavy metal containing calcium supplements. I do not recommend use of fluoride or strontium for treatment of osteoporosis. Much better choices are available that are effective and safe.