Strontium has fundamental chemical similarities to calcium. When dietary intake of strontium is raised, strontium begins to take the place of calcium in developing bone. This replacement appears to be beneficial (at least with low doses of strontium—see Safety Issues), leading to an increase in bone formation, a decrease in bone breakdown, and an overall rise in bone density.^1-5

The net result is a reduced incidence of fractures due to osteoporosis, according to two very large studies.^1,6

In addition, highly preliminary evidence hints that strontium might also help prevent cavities by strengthening dental enamel.⁷

In a 3-year, double-blind, placebo-controlled study of 5,091 women with osteoporosis, use of strontium at a dose of 2 grams daily significantly improved bone density and reduced incidence of all fractures as compared to placebo.¹ Additionally, in a 3-year, double-blind, placebo-controlled study of 1,649 postmenopausal women with osteoporosis and a history of at least one vertebral fracture, use of strontium ranelate at a dose of 2 grams daily reduced the incidence of new vertebral fractures by 49% in the first year and 41% in the full 3-year period (as compared to placebo).⁶ Use of strontium also significantly increased measured bone density. No significant side effects were seen.

Benefits were also seen in an earlier, smaller study.⁵

A fourth study tested strontium ranelate for preventing osteoporosis in postmenopausal who have not yet developed it.⁴ In this 2-year, double-blind, placebo-controlled study, 160 women received either placebo or strontium ranelate at a dose of 125 mg, 500 mg, or 1 gram daily. The results showed greater gains in bone density the more strontium taken.

While some treatments for osteoporosis act to increase bone formation, and other decrease bone breakdown, some evidence suggests that strontium ranelate has a dual effect, providing both these benefits at once.¹⁴

Other forms of strontium besides strontium ranelate, such as strontium chloride, have shown potential benefits in animal studies, but have not undergone significant testing in people.^3,8-13

When taken in recommended doses, strontium supplements appear to be safe and usually free of side effects other than occasional mild gastrointestinal upset, including diarrhea. There is some weak evidence that long term use of strontium ranelate could, rarely, cause memory loss or seizures.¹⁵ Similarly weak evidence hints that strontium could raise risk of blood clots;¹⁵ however, one small study was somewhat reassuring on this score.¹⁶

Excessive intake of strontium can actually weaken bone by replacing too much of the bone’s calcium with strontium.¹¹

Maximum safe doses of strontium in young children, pregnant or nursing women, or people with severe liver or kidney disease have not been established.