Life Extension Extend-Release Magnesium is formulated with two kinds of magnesium, and is optimized for both immediate and prolonged dissolution and uptake. Your body needs magnesium for more than 300 essential biochemical reactions, but most of us don't get enough magnesium from dietary sources alone. Extend-Release Magnesium is formulated with magnesium oxide for extended release and magnesium citrate for immediate absorption to provide more consistent results from this supplement.Optimize the cardiovascular and bone health benefits of a magnesium supplement with the immediate and prolonged uptake of Extend-Release Magnesium’s six-hour formula.