Magnesium is involved in energy supply and may be of benefit for athletes or individuals suffering from chronic fatigue. Magnesium improves insulin and glucose control, and may help in treating metabolic syndrome. Magnesium is helpful in reducing the symptoms of PMS in women. Magnesium supplementation is specifically indicated for individuals taking the following medications which cause magnesium depletion: beta-agonists (asthma medication), estrogen containing oral contraceptives and hormone replacement therapy, digoxin, diuretics (except potassium sparing diuretics) and cortisone medications (corticosteroids). The following groups of people are at particular risk of low magnesium levels and should supplement with magnesium: diabetics, the elderly and people who drink a lot of alcohol. Magnesium glycinate is the most bioavailable and absorbable form of magnesium and the least likely to cause diarrhoea as a side effect.