Magnesium (2)

Sources of Magnesium.
Good sources of magnesium in the diet are confined mainly to wholegrain cereals, nuts, beans
and seeds. Other very good sources of magnesium include leafy green vegetables, like spinach.
The effect of milling on the magnesium content of cereals can be seen by comparing the content in a portion of brown rice with white rice or a slice of wholemeal bread with white bread.
Cereal refining was responsible for an estimated 50 per cent decline in magnesium intake in the 20th century.
For a table with the most common sources plus the contents of Magnesium in each, please email me.

Function of Magnesium
The body contains about 25g of magnesium: 50 per cent in bone, 27 per cent in muscle, 19 per cent in other soft tissues, and only 1 per cent in blood.
Magnesium functions in most systems of the body, including energy pathways, the replication of DNA and synthesis of RNA. Its role is intimately linked to that of calcium. Indeed, low blood magnesium enhances parathyroid hormone secretion, which promotes bone demineralisation.
At the cellular level, magnesium can act as a calcium channel blocker by inhibiting the calcium entry into the cell (where calcium regulates cell activity).
In the nervous system, magnesium acts at synapses (the gaps between nerve cells) as a depressant. Furthermore, the mineral can inhibit the release of adrenalin, high levels of which increase urinary magnesium output, perpetuating a vicious cycle of deficiency.

Magnesium is excreted by the kidneys, and urinary output increases with increasing doses up to 2g daily. Higher intakes are unabsorbed and laxative – hence the traditional use of Epsom salts (magnesium sulphate) for constipation. Normally, the kidneys are excellent at regulating blood levels of magnesium and hence it is difficult to demonstrate low body magnesium status through plasma magnesium concentration in normal healthy people. This is especially so as equilibrium between the body tissues is slow – up to 100 days – so plasma magnesium values do not fully reflect total body status.
More to follow . . .