Strontium
Summary
Strontium is a calcium-like mineral. As the prescription drug strontium ranelate (2 g/day), it cut new vertebral fractures by about 40% in women with osteoporosis (grade A), but EU regulators restricted it in 2014 over heart-attack and blood-clot risk. No fracture trial has tested the strontium citrate sold as supplements, and strontium inflates bone-density scans.
Key facts
- Strontium ranelate 2 g/day reduced new vertebral fractures by 37% over 3 years in a Cochrane meta-analysis (RR 0.63; 2 trials, n = 5,082)[3]
- In 2014 the EMA limited strontium ranelate to severe osteoporosis when no other medicine can be used, and barred it after heart attack, stroke or arterial disease[4]
- Servier stopped marketing Protelos in the EU in 2017, and its EU authorisation was withdrawn in 2020 at the company's request for commercial reasons[11]
- Pooled trials: heart attack 1.7% vs 1.1% on placebo (RR 1.6); venous clots 1.9% vs 1.3% (RR 1.5)[4]
- No fracture or bone-density trial has tested strontium citrate; a 10-woman study showed bone strontium kept rising for over 4 years[7]
- Strontium in bone exaggerates DXA bone density; about half of the 3-year BMD gain on the drug reflects this physical effect[5][6]
- 4 graded human outcomes on this page
- October 13, 2026
How it works
ProposedStrontium is taken up into bone mineral in place of calcium, mostly adsorbed onto the crystal surface. The drug label describes increased bone formation and reduced resorption in non-clinical models; in humans, fracture reduction is established for strontium ranelate, while the share of the bone-density rise that reflects new bone versus heavier strontium atoms is uncertain.[5][6]
What the human research says
Human trials only, one row per outcome. The form column shows what each trial actually tested. Grades follow our evidence-grading policy.
At a glance: strongest evidence per outcome
| Outcome | Grade | Effect | Strongest evidence | Rows |
|---|---|---|---|---|
| Fractures | Grade A | Improved | Meta-analysis of 2 trials · n = 5,082 · 2006 | 3 rows |
| Heart safety | Grade D | No effect | Observational · n = 67,034 · 2014 | 1 row |
Every graded row
| Outcome | Effect | Grade | Best evidence | PMID |
|---|---|---|---|---|
| Vertebral and non-vertebral fractures (strontium ranelate, pooled) | Improved | Grade A | Meta-analysis · n = 5,082 · 2006 Postmenopausal women with osteoporosis (4 trials; vertebral analysis from 2 trials) Form: Strontium ranelate (prescription drug) · Dose: 2 g/day (lower doses 0.125–1 g/day in other arms) · Duration: 3 years Vertebral fractures fell by 37% (RR 0.63) and non-vertebral fractures by 14% (RR 0.86; n = 6,572). Diarrhoea was more common, and vascular and nervous-system side effects were slightly increased with 2 g/day. | 16856092 (opens PubMed)Source [3] |
| Non-vertebral and hip fractures (strontium ranelate) | Improved | Grade B | RCT · n = 5,091 · 2005 Postmenopausal women with osteoporosis (TROPOS trial) Form: Strontium ranelate (prescription drug) · Dose: 2 g/day · Duration: 3 years (main analysis of a 5-year study) All non-vertebral fractures fell by 16% (P = 0.04) and major fragility fractures by 19%; in a high-risk subgroup (age 74+ with very low hip BMD) hip fractures fell by 36% (P = 0.046). | 15728210 (opens PubMed)Source [2] |
| New vertebral fractures (strontium ranelate) | Improved | Grade B | RCT · n = 1,649 · 2004 Postmenopausal women with osteoporosis and at least one vertebral fracture (SOTI trial) Form: Strontium ranelate (prescription drug), with calcium and vitamin D in both arms · Dose: 2 g/day · Duration: 3 years New vertebral fractures fell by 49% in year 1 and 41% over 3 years (RR 0.59); lumbar spine BMD rose 14.4% and femoral neck 8.3%. Serious adverse events did not differ in the published report. | 14749454 (opens PubMed)Source [1] |
| Acute coronary syndrome in real-world users (strontium ranelate vs bisphosphonates) | No effect | Grade D | Observational · n = 67,034 · 2014 Postmenopausal women starting osteoporosis drugs in Denmark, 2005–2011 Form: Strontium ranelate (prescription drug) · Dose: Prescribed dose · Duration: Study period 2005–2011 Strontium users (n = 1,798) did not have a significantly higher rate of acute coronary syndrome than alendronate or risedronate users (adjusted HR 0.89, 95% CI 0.52–1.55). | 24651624 (opens PubMed)Source [9] |
Forms
| Form | Elemental % | Absorption (human data) | GI tolerance | Studied for |
|---|---|---|---|---|
| Strontium ranelate (prescription drug) | 34.1%[10] | Absolute bioavailability about 25% after 2 g; food, milk and calcium cut it by about 60–70%, so the label separates doses by at least 2 hours.[5] | More diarrhoea than placebo; pooled trials showed more heart attacks and venous clots; rare severe skin reactions (SJS, TEN, DRESS) are listed on the label.[3][4][5] | Fracture trials in postmenopausal osteoporosis (0.125–2 g/day) |
| Strontium citrate (dietary supplement) | Varies[7] | In 10 women self-supplementing, bone strontium measured by X-ray fluorescence rose within 24 hours and kept rising for over 4 years, with wide variation between people.[7] | No controlled safety data for supplement salts were found.[7] | Bone strontium uptake only; no fracture or BMD trials |
Compound weight → elemental strontium
500 mg strontium ranelate (prescription drug) ≈ 171 mg elemental strontium
Studied doses
Doses studied in human trials ranged from 0.125 to 2 g/day of strontium ranelate for 1 to 5 years, with 2 g/day used in the fracture trials. No fracture trial has tested strontium citrate or other supplement salts.[3][1][2]
Dose math: how much compound supplies that much strontium
| Form (elemental %) | 680 mg strontiumAbout 680 mg: elemental strontium in 2 g of anhydrous strontium ranelate (fracture-trial dose) |
|---|---|
| Strontium ranelate (prescription drug) (34.1%) | ≈ 1,990 mg compound |
Interactions
Published interactions only: each row cites a source. No row means none was found in our sources, not that a combination is safe.
Medicines
- Oral tetracycline and quinolone antibioticsDrug labelDivalent strontium can bind these antibiotics in the gut and reduce their absorption; the label pauses strontium ranelate during such courses.[5]
Other supplements
- Calcium, food and dairyDrug labelReduce strontium ranelate absorption by about 60–70%; the label separates them by at least 2 hours.[5]
Who should be careful
- Heart and circulation disease
- The EMA barred strontium ranelate in people with current or past ischaemic heart disease, peripheral arterial disease, cerebrovascular disease or uncontrolled high blood pressure.[4]
- Blood clots
- The drug label contraindicates strontium ranelate after current or previous venous thromboembolism, including deep vein thrombosis and pulmonary embolism.[5]
- Severe kidney impairment
- The label does not recommend strontium ranelate when creatinine clearance is below 30 mL/min.[5]
Talk to your pharmacist or clinician before starting a supplement, especially if you take prescription medicines.
Effects on tests
- Bone density scans
- A 1% molar share of strontium in bone mineral makes DXA overestimate BMD by about 10%. Bone-density changes on strontium overstate real bone gain.[6][5]
- Calcium blood and urine tests
- Strontium interferes with colorimetric calcium assays; the label points to ICP-AES or atomic absorption methods instead.[5]
How to read the label
- Supplement vs drugThe fracture evidence is for strontium ranelate 2 g/day, a prescription drug. Strontium citrate supplements were never tested for fractures.[3][7]
- Elemental strontium2 g of anhydrous strontium ranelate holds about 680 mg of strontium; supplement labels should state elemental strontium so amounts can be compared.[10]
- Tell whoever reads your scansBecause strontium inflates DXA results, the label says to take it into account when interpreting bone-density changes.[5]
Cost per studied dose, without the sales pitch
Compare any product you already have by the amount it delivers, not by capsule count or front-of-pack weight.
Cost per studied dose
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Frequently asked questions
Does strontium build bone?
The prescription drug strontium ranelate (2 g/day) reduced vertebral fractures by about 40% over 3 years. Part of its bone-density rise on scans is an artefact of strontium itself.[1][3][5]
Is strontium citrate the same as strontium ranelate?
No. Both deliver strontium, but only the ranelate drug was tested in fracture trials. Strontium citrate supplements have bone-uptake data in 10 women and no fracture data.[7][3]
Why was strontium ranelate restricted?
Pooled trial data showed more heart attacks (1.7% vs 1.1%) and venous clots (1.9% vs 1.3%) than placebo, so the EMA limited it in 2014 to patients without cardiovascular disease who cannot use other osteoporosis medicines.[4]
Will strontium change my bone density scan?
Yes. Strontium is heavier than calcium, so DXA overestimates bone density; about half of the scan gain on the drug came from this effect.[5][6]
Does calcium interfere with strontium?
Calcium and food cut strontium ranelate absorption by about 60–70%; the drug label separates them by at least 2 hours.[5]
Does strontium affect blood tests?
It interferes with colorimetric calcium assays in blood and urine; labs need ICP or atomic absorption methods for an accurate calcium result.[5]
Sources
- [1]The effects of strontium ranelate on the risk of vertebral fracture in women with postmenopausal osteoporosis.. N Engl J Med, 2004. RCT
- [2]Strontium ranelate reduces the risk of nonvertebral fractures in postmenopausal women with osteoporosis: Treatment of Peripheral Osteoporosis (TROPOS) study.. J Clin Endocrinol Metab, 2005. RCT
- [3]Strontium ranelate for preventing and treating postmenopausal osteoporosis.. Cochrane Database Syst Rev, 2006. meta-analysis
- [4]Protelos and Osseor (strontium ranelate): Article 20 referral, further restrictions on use. European Medicines Agency, 2014. safety-communication
- [5]Protelos (strontium ranelate) 2 g granules: summary of product characteristics (Article 20 procedure product information). European Medicines Agency, 2014. label
- [6]The correction of BMD measurements for bone strontium content.. J Clin Densitom, 2007. review
- [7]Monitoring bone strontium intake in osteoporotic females self-supplementing with strontium citrate with a novel in-vivo X-ray fluorescence based diagnostic tool.. Bone, 2014. open-label
- [8]A comparison of adverse event and fracture efficacy data for strontium ranelate in regulatory documents and the publication record.. BMJ Open, 2014. review
- [9]Use of strontium ranelate and risk of acute coronary syndrome: cohort study.. Ann Rheum Dis, 2014. observational
- [10]Strontium ranelate (CID 6918182): compound summary. PubChem, NCBI, 2026. database
- [11]Protelos: withdrawal of the marketing authorisation in the European Union. European Medicines Agency, 2020. safety-communication
What changed
- Independent review: SOTI row regraded A to B (a single RCT; the grade A rests on the Cochrane meta-analysis row); added the 2017 market discontinuation and 2020 EU withdrawal of Protelos (EMA EPAR). All PMIDs re-checked.
- Strict second-pass self-review (no separate reviewer could be dispatched for this batch): all 7 PMIDs re-verified by NCBI esummary (titles and years match the record) and efetch checked for retraction, expression-of-concern and erratum flags (none flagged); every evidence row, key fact, form, dose, label line, FAQ and insight re-read against its abstract, and against PMC full text where the dose or count lives. Fixes: Cochrane citation switched to the 2006 version whose abstract carries the participant counts (PMID 16856092); linter wording fixed; Danish cohort duration restated as the study period. Page set indexable.
- First draft. Every PMID checked against NCBI E-utilities esummary (title and year from the record) and abstracts read for each cited row. EMA referral page and the 2014 Protelos product information (sections 4.2–4.5, 5.1, 5.2) read directly. Elemental fraction computed from the PubChem formula. No NIH ODS or NCCIH fact sheet covers strontium.