Also known as: Strontium Citrate, Strontium Ranelate
Strontium is a trace mineral that accumulates in bone tissue due to its chemical similarity to calcium. Strontium ranelate has demonstrated significant anti-fracture efficacy in postmenopausal osteoporosis, though cardiovascular safety concerns have restricted its clinical use.
Strontium is a naturally occurring alkaline earth metal that shares chemical properties with calcium and preferentially incorporates into bone mineral at sites of active remodeling. The pharmaceutical form, strontium ranelate (Protelos), was approved in Europe for osteoporosis treatment based on large randomized trials (SOTI and TROPOS) showing 37–41% reductions in vertebral fracture risk and 16% reductions in non-vertebral fractures. Its dual mechanism involves both stimulation of osteoblast-mediated bone formation and inhibition of osteoclast-mediated bone resorption. However, post-marketing surveillance revealed increased cardiovascular risks, including myocardial infarction and venous thromboembolism, leading the EMA to restrict its use to severe osteoporosis patients without cardiovascular disease. Over-the-counter strontium citrate supplements are marketed as a bone health alternative but lack the clinical trial evidence of the ranelate salt. Importantly, strontium artificially inflates DXA bone density measurements by approximately 10% due to its higher atomic number, which must be accounted for in clinical interpretation.
The SOTI trial demonstrated that strontium ranelate 2 g/day reduced new vertebral fractures by 41% over 3 years in postmenopausal women with osteoporosis compared to placebo.
Strontium ranelate has a unique dual mechanism of action: it increases osteoblast differentiation and activity while simultaneously reducing osteoclast function, making it distinct from purely anti-resorptive therapies.
At bedtime on an empty stomach, separated from calcium supplements by at least 2 hours
Strontium competes with calcium for absorption. Never take at the same time as calcium supplements or calcium-rich foods. OTC strontium citrate has far less clinical evidence than the prescription ranelate form.
Over-the-counter bone health supplementation
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