Monograph prepared by Michael Uzick, N.D.
Strontium citrate - Each capsule contains:
667mg (200mg elemental strontium)
Recommended Dosage - 3 capsules daily with or without food, in conjunction with an adequate daily intake of calcium.
Osteoporosis (secondary to menopause, decreased activity or prolonged glucocorticoid exposure)
First discovered in Strontian , Scotland , strontium is a mineral that is naturally present in food and water and in trace amounts throughout the skeleton. Naturally-occurring, stable strontium is non-toxic and should not be confused with its radioactive isotope. First used in the 1940s and 50s as a treatment for osteoporosis, strontium demonstrated significant benefits without side effects. This initial research utilized a strontium ion dosage 2.5 times greater than recent controlled clinical trials. (1) Standard therapies for menopausal osteoporosis act only by decreasing bone resorption and do not increase bone tissue mass. These therapies also inhibit an already impaired bone forming capacity. (2) As such, these therapies can not be used for forms of osteoporosis resulting from decreased bone formation. Strontium, on the other hand, both decreases bone resorption and increases bone formation, resulting in significant increases in bone mineral density and reduced risk of fracture. (3-7) Thus, strontium appears to be a unique, safe and effective natural aid for osteoporosis resulting from multiple causes.
In vitro, animal and human studies have all shown strontium salts to both increase bone formation and decrease bone resorption, resulting in significant increases in bone density. (3-8) At the cellular level, strontium enhances the activity of osteoblasts while simultaneously reducing osteoclastic activity. Intestinal absorption of strontium is about 25-30% of which 50-80% is taken up by the bones. (8, 9) In the presence of calcium, strontium absorption is reduced by half. Intestinal absorption is vitamin-D dependent and decreases with aging, food and diets high in other minerals. When unbound by serum proteins, strontium is cleared by urinary and fecal routes. The remaining mineral is retained in soft and mostly calcified tissues. In primates, the strontium content of bone decreases by 50% within 6 weeks of treatment cessation. Elimination from the skeleton has an initial half-life of 41 days, followed by a slower half-life of 3 years. (8)
A 3-year, randomized, double-blind, placebo-controlled trial assessed the efficacy of strontium on vertebral fracture and bone mineral density (BMD) among 1,442 postmenopausal women with osteoporosis and a history of a least one vertebral fracture. Women were treated with calcium (diet + supplements = 1500 mg/d) and vitamin-D (400 or 800 IU/d) and either 2 grams strontium ranelate (680 mg of elemental strontium) or placebo. The results were that lumbar fracture risk was reduced by 41% after 3 years in the strontium group compared with placebo. BMD in the strontium group increased by 12.7% (lumbar spine), 7.2% (femoral neck), and 8.6% (total hip). The differences between strontium and placebo were 14.4%, 8.3%, and 9.8%, respectively. Adjusting for strontium content at the lumber spine showed an increase in bone density of 6.8% with a difference of 8.1% compared with placebo.* Strontium was also shown to significantly increase markers of bone formation and decrease markers of bone resorption compared with placebo. (3)
A randomized, double-blind, placebo-controlled trial assessed hip-fracture prevention and safety of strontium in 5,091 women with postmenopausal osteoporosis over a 3 year period. Patients received daily calcium and vitamin-D supplements (as above) and either 2 grams of strontium ranelate or placebo. The study showed a 41% reduction in the risk of fracture after a minimum of 18 months of treatment. (4)
A randomized, double-blind, placebo-controlled trial was conducted to establish the minimum effective dose of strontium in the treatment of postmenopausal osteoporosis. All 345 woman with a history of fracture, received calcium and vitamin D (as above) and either 0.5g, 1.0g, 2.0g daily of strontium ranelate or placebo. A dose of 2g daily was found to be the most efficacious with a 44% reduction in the risk of new vertebral fractures and a 3% increase in strontium-adjusted bone density after 2 years, compared with placebo.* Strontium was also shown to increase markers of bone formation and decrease markers of bone resorption compared with placebo. (5)
A randomized, double-blind, placebo-controlled trial was undertaken to determine the minimum dose of strontium necessary to prevent bone loss in early postmenopausal women without osteoporosis. Woman received 500mg of calcium carbonate and either 125mg, 500mg, 1g of strontium ranelate or placebo. Only the 1g dose was shown to increase significantly strontium-adjusted bone mineral density by 1.5% at the end of 2 years.* The difference in bone density between strontium and placebo was 2.4%. Strontium also significantly increased markers of bone formation. (6)
Patients with osteoporosis and chronic back pain were treated with strontium alone or in combination with hormone replacement therapy for up to 3 years. The 32 patients were given Strontium lactate 6.4g daily (1.7g elemental strontium). Patients were judged as mild (25%), severe (66%) and bedridden (9%). Results: Overall, 84% of patients showed marked subjective improvement. The remaining patients (16%) had moderate improvement. However, changes in radiographs were not evident in 7 patients and were equivocal in 78% of cases because of varying techniques and interpretations. (7)
Three capsules daily with or without food, preferably separate from other mineral supplements. An adequate daily intake of calcium and vitamin-D is recommended.
Pregnant woman and individuals with decreased renal function should avoid strontium unless otherwise advised by their physician.
In all of the clinical trials using a maximum dosage of 680 mg of elemental strontium, side effects were no greater than placebo. Bone biopsies from hundreds of animals and humans show no evidence mineralization defects or cellular toxicity resulting from strontium administration. (10) One trial found elevated serum creatine kinase in the skeletal muscle among 3.4% and 1.8% of the strontium and placebo groups. However, there was no increase in muscular pain or other abnormalities in these patients. Additionally, increases were mostly transient, normalizing in 88% of affected patients. (3)
Early animal studies employing a diet free of calcium and with strontium as the sole source of bone salts resulted in softening of the skeleton. (1) In a rat model of renal failure, high doses of strontium resulted in osteomalacia. Similarly, osteomalacia has been associated with high strontium exposure in dialysis patients. (11) However, there is no evidence of bone defects among intact animals or humans with moderate renal insufficiency treated with strontium. (10).
* CLINICAL NOTE
Bone mineral densities (BMD) reported in the above clinical trials were adjusted for strontium content. Since strontium has a greater density than calcium, radiographic assessment overestimates the bone density of subjects treated with it. Adjustments were calculated from the strontium content found on bone biopsy of study participants. Currently, there is no standard adjustment to apply to BMD assessments.
Shorr E, Carter AC. The usefulness of strontium as an adjuvant to calcium in the remineralization of the skeleton in man. Hosp Joint Dis Bull. 1952 Apr;13(1):59-66.
Eastell R. Treatment of postmenopausal osteoporosis. N Engl J Med. 1998 Mar 12;338(11):736-46.
Meunier PJ, Roux C, Seeman E, et al. The effects of strontium ranelate on the risk of vertebral fracture in women with postmenopausal osteoporosis. N Engl J Med. 2004 Jan 29;350(5):459-68.
J Y Reginster, A Sawicki, J P Devogelaer, et al. Strontium Ranelate Reduces the Risk of Hip Fracture in Women with Postmenopausal Osteoporosis. Osteoporos Int. 2002 Suppl 3:S14;O14.
Meunier PJ, Slosman DO, Delmas PD, et al. Strontium ranelate: dose-dependent effects in established postmenopausal vertebral osteoporosis--a 2-year randomized placebo controlled trial. J Clin Endocrinol Metab. 2002 May;87(5):2060-6.
Reginster JY, Deroisy R, Dougados M, et al. Prevention of early postmenopausal bone loss by strontium ranelate: the randomized, two-year, double-masked, dose-ranging, placebo-controlled PREVOS trial. Osteoporos Int. 2002 Dec;13(12):925-31.
Janes JM, McCaslin F. The effect of strontium lactate in the treatment of osteoporosis. Mayo Clin Proc 1959;34:329–334
Marie PJ, Ammann P, Boivin G, et al. Mechanisms of action and therapeutic potential of strontium in bone. Calcif Tissue Int. 2001 Sep;69(3):121-9.
Boivin G, Deloffre P, Perrat B, et al. Strontium distribution and interactions with bone mineral in monkey iliac bone after strontium salt (S 12911) administration. J Bone Miner Res. 1996 Sep;11(9):1302-11.
Meunier, Pierre J. Postmenopausal osteoporosis and strontium ranelate. N Engl J Med. 2004 May 6;350(19):2001-3.
Schrooten I, Cabrera W, Goodman WG, et al. Strontium causes osteomalacia in chronic renal failure rats. Kidney Int. 1998 Aug;54(2):448-56.