Harvard Women's Health Watch

Ask the doctor: Should I have my magnesium level checked?

Q. Should I have my magnesium level checked regularly to make sure I'm getting enough for my bones?

A. You need adequate magnesium, and not just for bone health. It's central to hundreds of biochemical reactions throughout the body and essential for proper nerve, muscle, heart rhythm, and immune function. It also helps regulate blood sugar levels and promotes healthy blood pressure. We get most of the magnesium we need in food (good sources are whole grains, legumes, and dark-green leafy vegetables). Most multivitamins also contain some magnesium.

Magnesium is absorbed in the intestine and travels through the blood to cells and tissues; any excess is excreted through the kidneys. About half of the magnesium we absorb is stored in bone; the other half, in cells throughout the body. Only a little is found in blood. As a result, the blood level of magnesium doesn't tell us much about the body's total store of the mineral.

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