Now Magnesium Supplement supplies your body with 400mg of Magnesium, the mineral necessary for energy production and metabolism, muscular contraction, nerve impulse transmission, and bone mineralisation. Magnesium level also influences calcium balance via the parathyroid gland. Magnesium functions as a natural calcium blocker, allowing your muscle cells to rest after contraction. When magnesium levels are low, your muscles may tense excessively, resulting in cramps or muscle spasms. Magnesium insufficiency causes muscular weakening and injury.