Magnesium is a macro (major) mineral.
    Magnesium plays important roles in the structure and the function of the human body. The adult human body contains about 25 grams of magnesium. Over 60% of all the magnesium in the body is found in the skeleton, about 27% is found in muscle, while 6 to 7% is found in other cells, and less than 1% is found outside of cells.
    The occurrence of sudden cardiac death is lower among persons living in hard water than among those persons drinking soft water. As a result, the higher magnesium levels in hard water have been proposed as the protective factor against cardiac deaths.

A magnesium deficiency may be the root cause for cardiovascular disease, hypertension, asthma, chronic fatigue and pain syndromes, depression, insomnia, irritable bowel syndrome and many pulmonary disorders.
    Magnesium is required for the active transport of ions like potassium and calcium across cell membranes. Through its role in ion transport systems, magnesium affects the conduction of nerve impulses, muscle contraction, and the normal rhythm of the heart.

Men should have 400 milligrams every day. Women should have 300 milligrams every day.

Intake:

Recommended Dietary Allowance (RDA) for Magnesium
Babies 0-6 months	30 mg/day
Babies 7-12 months	75 mg/day
Children 1 to 3 years	80 mg/day
Children 4 to 8 years	130 mg/day
Children 9 to 13 years	240 mg/day
Teenagers boys 14 to 18	410 mg/day
Teenagers girls 14 to 18	360 mg/day
Adults men ages 19-30	400 mg/day
Adults women ages 19-30	310 mg/day
Adults men ages 31 years and older	420 mg/day
Adults women ages 31 years and older	320 mg/day
Pregnant women	350 mg/day

Magnesium is an essential nutrient required for many biologic functions in the body, including over 300 enzyme reactions. It also functions in the activation of amino acids and has an important role in neurotransmission and immune function.
    Accompanied by vitamin B-6 (pyridoxine), magnesium can help reduce and dissolve calcium phosphate kidney stones.
    Magnesium promotes the absorption and assimilation of other minerals including calcium, phosphorous, sodium and potassium and enables utilisation of vitamin B complex and vitamins C and E.

Green leafy vegetables are rich in magnesium. Unrefined grains and nuts also have high magnesium content. Meats and milk have an intermediate magnesium content. Water is a variable source of intake; harder water usually has a higher concentration of magnesium salts.