For the best in bone health, try Swanson Strontium Citrate! Strontium is one of the most abundant elements on earth. It's molecularly similar to calcium and is found in healthy bones and teeth. Strontium Citrate is a dietary form for supplementation, but because of its close molecular ties to calcium, it competes with absorption. That's why we recommend taking a quality calcium supplement along with our Strontium Citrate.