Suffering from anxiety/depression? Can't get to sleep? Suffering from night cramps/restless legs/menstrual cramps/muscle spasms/asthma/migraines? You may be deficient in magnesium. See Magnesium and the Brain: The Original Chill Pill , Magnesium and the Ketamine Connection , A case of oesophageal spasm, and the ‘unproven’ treatment that helped it and Around the Web; and Menstrual Cramp Remedy.
After Vitamin D and Omega-3 fats, magnesium is the third nutrient in which people are likely to be deficient. Processed foods are low in magnesium. Diets low in green vegetables are low in magnesium, as chlorophyll has magnesium at the centre of the molecule. For a list of the 999 richest sources of magnesium per 100g serving, see http://nutritiondata.self.com/foods-000120000000000000000-w.html. Too much calcium can result in a relative magnesium deficiency.
An optimum intake of magnesium is approximately 50% of your calcium intake. Other sources of magnesium are Milk of Magnesia (magnesium hydroxide) and Epsom Salts (magnesium sulphate heptahydrate). A large amount (~4g) of Epsom Salts taken in one dose acts as an osmotic laxative, but spreading the same amount over 24 hours has no laxative effect. Approximately a level teaspoonful (~4g) of Epsom Salts gives you ~400mg of magnesium. Epsom Salts is as cheap as chips.
Magnesium is also available as a dietary supplement. Magnesium oxide (Magnesia) isn't as well-absorbed as magnesium citrate/amino acid chelate, so take extra if using oxide. See Magnesium bioavailability from magnesium citrate and magnesium oxide. Magnesium can be absorbed through the skin, so adding Epsom Salts or Magnesium Chloride to your bathwater is another option.
6.1.15. New article: Magnesium in Man: Implications for Health and Disease.