Strontium — Research Profile

Both are true to some degree. Strontium genuinely stimulates osteoblasts and inhibits osteoclasts, producing real bone-building effects. However, because strontium has a higher atomic number than calcium, DEXA scans overestimate BMD by about 10% when strontium is incorporated into bone. The SOTI and TROPOS trials showed actual fracture reduction, confirming real structural benefit beyond the measurement artifact.

Unknown. The fracture-reduction evidence comes from strontium ranelate trials. Strontium citrate provides the same elemental strontium but has not been studied in large RCTs. The ranelic acid component may contribute additional effects beyond strontium alone. Many bone health practitioners use strontium citrate as an affordable alternative, but the evidence is extrapolated, not proven.

Strontium and calcium use the same intestinal absorption pathways and directly compete for uptake. Taking them together dramatically reduces strontium absorption. For best results, take strontium at bedtime on an empty stomach, and take calcium supplements at a different time of day (morning or with meals).

Strontium ranelate is the only form with randomized fracture-outcome trials, but it is a restricted, largely withdrawn prescription drug rather than a supplement. Among over-the-counter options, strontium citrate is the most common, yet no supplemental salt has been shown to reduce fractures, and in a head-to-head animal comparison citrate produced smaller gains in bone-mineral density and lower strontium uptake than ranelate. No supplemental form is proven superior in people, so citrate is the practical default rather than an evidence-backed best choice.

The strongest evidence is for prescription strontium ranelate, which cut vertebral fractures by about 41% over three years and also lowered non-vertebral fracture risk in postmenopausal osteoporosis, with benefit maintained to 10 years; a Cochrane review confirms fracture reduction (vertebral RR 0.63) in this population. These outcomes have not been demonstrated for over-the-counter strontium citrate. Reported DXA bone-density gains also overstate the true effect, because strontium attenuates X-rays more strongly than calcium and inflates the density reading independent of new bone.

The only dose validated for fracture prevention is 2 g/day of strontium ranelate, taken once daily as a prescription drug. There is no recommended dietary allowance because strontium is not an essential nutrient, and over-the-counter strontium citrate has not been tested in fracture-outcome trials, so no supplemental dose is reliably established. If used at all, it should be under medical supervision rather than to a self-selected target.

Take strontium on an empty stomach and away from calcium, because food, milk, and calcium markedly reduce its absorption. The strontium ranelate label directs dosing at bedtime, at least two hours after eating or taking calcium, which is a sensible rule for citrate as well. The gap from meals and calcium matters more than the specific hour of the day.

In strontium ranelate trials the common complaints were nausea, diarrhea, and headache, most of which eased over time. The serious concerns are cardiovascular: pooled trials showed more heart attacks with strontium ranelate than placebo (1.7% vs 1.1%), and the drug also carries a documented risk of venous blood clots. Severe hypersensitivity reactions, including DRESS syndrome, have been reported with strontium ranelate and even with over-the-counter strontium citrate, so a spreading rash with fever warrants stopping the supplement immediately.

Strontium chelates oral tetracycline and quinolone (fluoroquinolone) antibiotics and reduces their absorption, so separate them by several hours. Calcium supplements, food, and magnesium- or aluminum-containing antacids likewise cut strontium absorption. Strontium ranelate is contraindicated in people with ischemic heart disease, peripheral arterial disease, cerebrovascular disease, or uncontrolled hypertension because of its heart-attack signal, so it must be reviewed against any cardiovascular medication and diagnosis.

Strontium is aimed at postmenopausal women, and men, with established osteoporosis; under European labeling strontium ranelate is limited to severe osteoporosis in those who cannot tolerate first-line drugs such as bisphosphonates. It is not appropriate for healthy people seeking general bone support. It should be avoided by anyone with a history of ischemic heart disease, peripheral arterial or cerebrovascular disease, uncontrolled hypertension, or venous blood clots.

Strontium acts on the slow bone-remodeling cycle, so meaningful change takes months rather than weeks. In the pivotal SOTI trial of strontium ranelate, new vertebral fractures were reduced within the first year and by about 41% over three years. Bone-density readings climb over the first months, but part of that apparent gain is a measurement effect: strontium attenuates X-rays more strongly than calcium, so DXA overestimates true bone-mineral density when strontium is present in bone, and the numbers overstate genuine new bone.

Prescription strontium ranelate has efficacy and safety data extending to 10 years, but European regulators restricted it in 2014 to severe osteoporosis in people unable to use other treatments after pooled trials showed more heart attacks. Over-the-counter strontium citrate has been used for months to years without that same reported clot and heart signal, but it lacks comparable long-term controlled safety trials. Long-term daily use is reasonable only with attention to cardiovascular risk factors, not as an open-ended supplement for otherwise healthy bones.

There is no established tolerable upper intake level for supplemental strontium, because it is not an essential nutrient with a defined requirement. The highest dose tested in controlled fracture trials was 2 g/day of strontium ranelate, so there is no evidence base for exceeding it. Because the prescription form was linked to a higher rate of heart attacks and higher intakes have not been shown to add benefit, going beyond studied doses adds risk without demonstrated gain.

Keep strontium separate from calcium: calcium, milk, and food substantially reduce strontium absorption, which is why strontium ranelate is taken at bedtime at least two hours after food or calcium. You still need adequate calcium and vitamin D for bone health, so take those at a different time of day rather than dropping them. Magnesium- or aluminum-containing antacids also blunt strontium uptake and should be spaced apart.

Most over-the-counter products are strontium citrate rather than the strontium ranelate used in the fracture trials, so that fracture-prevention evidence does not directly transfer. Different strontium salts carry different amounts of actual (elemental) strontium for a given weight, so check that the label specifies elemental strontium content rather than just total salt weight. Because a supplement's fracture benefit is unproven, treat it as an adjunct and favor products that disclose elemental milligrams and provide independent third-party purity testing.