Strontium
A mineral chemically similar to calcium that, as the prescription drug strontium ranelate, reduced fractures in large trials but was restricted in Europe over cardiovascular risk; the supplement form (strontium citrate) has no fracture trials and distorts bone density scans.
At a Glance
- Best known for
- Reduced vertebral and hip fractures (strontium ranelate, prescription form), Stimulates bone-forming cells while slowing bone breakdown, Increases measured bone mineral density (partly an artifact of its atomic weight)
- Evidence
- Moderate
- Typical dose
- 2 g strontium ranelate (680 mg elemental strontium) daily
- Type
- Mineral
What is Strontium?
Strontium is a soft, silvery metal that sits directly below calcium on the periodic table and behaves similarly in the body, concentrating in bone. (Non-radioactive strontium in supplements is unrelated to the radioactive strontium-90 from nuclear fallout.) Strontium's bone effects were noted in the 1950s, but serious interest came with strontium ranelate, a prescription drug developed in France that was shown in two large trials to reduce fractures in postmenopausal women. The drug was approved across Europe in 2004, then restricted in 2013–2014 to patients without cardiovascular disease after analyses showed increased heart attack risk, and its manufacturer withdrew it in 2017. It was never approved in the United States. Strontium citrate and other salts are sold as supplements on the strength of the ranelate research, but the salts themselves have not been tested for fracture prevention.
Known Health Benefits
How It Works
Strontium is unusual among bone agents in appearing to both stimulate bone formation and inhibit resorption. It activates the calcium-sensing receptor on osteoblasts, increasing their replication and collagen production, and increases osteoprotegerin while decreasing RANKL, which reduces osteoclast formation and activity. Strontium ions substitute for a small fraction of calcium in the hydroxyapatite crystal of bone, and because strontium has a higher atomic number than calcium, it absorbs more X-rays, which artificially inflates bone density readings on DEXA scans — roughly half of the measured density gain in trials was this artifact. In cartilage, strontium ranelate stimulated proteoglycan synthesis and reduced matrix-degrading enzymes, which led to osteoarthritis trials.
What Research Says
The evidence comes almost entirely from strontium ranelate. The SOTI trial (2004, 1,649 postmenopausal women with osteoporosis and prior vertebral fracture) found 2 g daily reduced new vertebral fractures by 41% over 3 years. The TROPOS trial (2005, 5,091 women) found a 16% reduction in all non-vertebral fractures and, in women over 74 with low hip density, a 36% reduction in hip fractures. A 2013 trial (SEKOIA, 1,371 patients) found strontium ranelate slowed knee osteoarthritis joint space narrowing. However, pooled analysis of the trials found a 1.6-fold increase in myocardial infarction, along with the previously known increased risk of blood clots and rare life-threatening skin reactions, leading the European Medicines Agency to restrict use to severe osteoporosis in patients without heart disease. Whether the cardiovascular risk comes from strontium itself or the ranelic acid carrier is unknown. Strontium citrate has only small, short studies showing increased bone density (which the artifact issue clouds); no trial has tested it for fractures or cardiovascular safety. A 2017 observational cohort suggested lower fracture risk in ranelate users but could not address supplement forms.
Active Compounds
Strontium (Sr2+); supplements contain strontium citrate, carbonate, or gluconate; the studied drug is strontium ranelate
Forms & Bioavailability
Strontium is absorbed through the same intestinal pathways as calcium, with absorption around 25–30%, declining when taken with calcium, dairy, or antacids, which compete for uptake — this is why it should be taken at least 2 hours apart from calcium and ideally at bedtime on an empty stomach. Absorbed strontium is incorporated into bone over months and retained for years; bone strontium levels continue rising with ongoing use, and the long-term consequences of high bone strontium content are not fully known, though trial follow-ups of up to 10 years with ranelate did not show deterioration in bone quality. Vitamin D improves strontium absorption as it does calcium.
Dosage Guidance
| Use Case | Dosage |
|---|---|
| Osteoporosis (trial dose of strontium ranelate) | 2 g strontium ranelate (680 mg elemental strontium) daily |
| Strontium citrate supplement | 340–680 mg elemental strontium daily at bedtime |
| Combined with calcium and vitamin D | Strontium at night; calcium 1000–1200 mg and vitamin D in the morning or with meals |
| Monitoring | Inform the imaging center of strontium use before DEXA scans |
Always consult a healthcare provider for personalized dosing.
Natural Food Sources
- Trace amounts in most foods, especially grains, leafy vegetables, and dairy (1–3 mg per day typical intake)
- Seafood and seaweed
- Drinking water (varies by region)
- Dietary strontium is hundreds of times lower than supplement doses
Potential Side Effects
Nausea, diarrhea, headache; strontium ranelate: increased risk of heart attack, venous thromboembolism, and rare severe skin reactions (DRESS); falsely elevated bone density readings; theoretical bone mineralization defects at high doses or with low calcium
Who Should Avoid It
- History of heart attack, stroke, peripheral artery disease, or uncontrolled hypertension
- History of venous thromboembolism (DVT, pulmonary embolism) or prolonged immobilization
- Severe kidney disease (strontium is cleared by the kidneys)
- Pregnancy, breastfeeding, and children (strontium incorporates into growing bone)
- Low calcium or vitamin D intake (strontium without adequate calcium may impair bone mineralization)
- Phenylketonuria (strontium ranelate specifically contained aspartame)
Pregnancy & Lactation
Strontium is contraindicated in pregnancy and breastfeeding. It crosses the placenta and incorporates into fetal bone, and animal studies showed bone and tooth abnormalities in offspring. It also passes into breast milk. It has no role in women of childbearing age who are not using reliable contraception.
Known Drug Interactions
Calcium, dairy, and antacids reduce absorption (separate by 2 hours); strontium reduces absorption of tetracycline and quinolone antibiotics; caution with other bone drugs (bisphosphonates, denosumab) — no data on combinations
Evidence Classification
Supported by cohort studies, case-control studies, or multiple observational studies with consistent findings.
Frequently Asked Questions
Is strontium citrate as effective as strontium ranelate?
Nobody knows. All the fracture-prevention evidence is for strontium ranelate, a specific drug. Strontium citrate delivers the same strontium ion, and the strontium is presumed to be the active part, but no trial has tested strontium citrate for fractures, and the cardiovascular risk seen with ranelate has not been studied for citrate either. Supplement makers borrow the drug's evidence; users should be aware of that gap.
Why was strontium ranelate withdrawn?
Pooled analysis of its trials showed about a 60% relative increase in heart attacks, on top of a known increase in blood clots and rare severe allergic skin reactions. In 2013–2014 European regulators restricted it to patients with severe osteoporosis who could not use other treatments and had no cardiovascular disease. With prescriptions falling, the manufacturer stopped production in 2017. A generic was later authorized, but use remains limited.
Will strontium improve my bone density scan?
Yes, but partly falsely. Strontium atoms absorb X-rays more strongly than calcium, so a DEXA scan over-reads density in strontium-containing bone. In ranelate trials roughly half of the apparent density gain was this artifact. Tell your imaging provider you take strontium so results can be interpreted properly; actual fracture-reduction data exist only for the drug form.
Can I take strontium with my calcium supplement?
Not at the same time. Calcium and strontium compete for absorption, so taking them together substantially reduces strontium uptake. Take strontium at bedtime on an empty stomach and calcium with meals earlier in the day. Adequate calcium and vitamin D remain essential, since strontium without calcium may produce poorly mineralized bone.
References
- The effects of strontium ranelate on the risk of vertebral fracture in women with postmenopausal osteoporosis. Meunier PJ, Roux C, Seeman E, et al.. N Engl J Med (2004)View study
- Strontium ranelate reduces the risk of nonvertebral fractures in postmenopausal women with osteoporosis: Treatment of Peripheral Osteoporosis (TROPOS) study. Reginster JY, Seeman E, De Vernejoul MC, et al.. J Clin Endocrinol Metab (2005)
- Recommendation to restrict the use of Protelos/Osseor (strontium ranelate). European Medicines Agency, Pharmacovigilance Risk Assessment Committee. EMA press release (2014)
Related Health Conditions
Related Supplements
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This entry is for educational purposes only. It is not medical advice. Always consult a qualified healthcare provider before starting, stopping, or changing any supplement regimen, especially if you take medications or have health conditions.