Strontium and calcium are two closely-related chemical elements that are necessary in the human diet for increasing bone density and the strength of high-stress bone structures like teeth. Despite their beneficial effects, strontium and calcium can interfere with each other in terms of absorption by the body due to the fact that they are both positively-charged chemicals in the same category on the periodic table of elements. Calcium can prevent the absorption of strontium, and strontium can replace calcium content in bones and teeth if they are taken separately. Both compounds are recommended as osteoporosis treatments, however, and are usually formulated into compounds where they will be absorbed better in combination, such as with calcium carbonate and strontium ranelate.
Research has shown that strontium is better at rebuilding bones with fewer side effects than previous compounds in the biphosphorate group such as aledronate or risedronate. Many people have an innate fear of the element strontium, however, because radioactive forms of it such as strontium-90 are a direct byproduct of nuclear weapons blasts. This type of radioactive strontium if present in the diet will also accumulate in bone structures and lead to cancer. Natural strontium is safe to ingest and is a common element in seawater and present in higher concentrations in soil than native carbon often is. Studies as of 1985 where 600 to 700 milligrams of strontium were included in the diet have demonstrated increasing bone density at levels of 172% above normal.
Medical studies have shown that strontium supplements taken alone reduce the effects of osteoporosis, and decrease the incidence of cavities and effects of arthritis. When strontium and calcium are taken together, though, these effects are reduced as the strontium is almost entirely flushed out of the body. Osteoporosis treatments generally recommend, therefore, that both of the minerals strontium and calcium be taken at least two hours apart from each other so that they can be absorbed into the blood stream separately. The absorption of both minerals can also be adversely affected if other supplements like magnesium and potassium are taken at the same time as well.
Since strontium and calcium are used by the same metabolic processes in the body, they also tend to be excreted in urine when various types of metabolic chemistry interfere with their use by human or animal biology. Strontium is most readily absorbed under fasting conditions, and both strontium and calcium are used more completely in children and pregnant women than other adult segments of the population. A deficiency in magnesium content in the body will inhibit the uptake of strontium and calcium. Phosphorus has also been shown to be a stronger inhibitor of strontium absorption than calcium is when both phosphorus and strontium supplements are taken together.