Date: February 17, 2017, 2:14 pm
Magnesium deficiency: a very modern problem
Magnesium: an essential mineral
Magnesium is one of the most important minerals in the human body. It is an essential cofactor for more than 300 chemical reactions, including those relating to heart rhythm, vascular tone, nerve function and muscle contraction and relaxation.
Magnesium is also necessary for tooth and bone formation, protein synthesis and cell division. In addition magnesium contributes to normal energy metabolism, healthy psychological function, reducing tiredness and fatigue; and in children magnesium contributes to normal growth and development.
Magnesium deficiency is increasingly being implicated in a large number of health conditions with much research ongoing.
How much magnesium do you need?
It is very important for people to consume magnesium regularly and in sufficient quantity in order to avoid deficiency. Around 300–350 milligrams per day is the minimum that all adults should be consuming.
Children also need to consume adequate magnesium as it is essential for their growth and development.
A table showing the recommended daily intake for different age groups can be found at:
Where are the best sources of magnesium?
The most significant source of magnesium is from the chlorophyll found in green leafy vegetables. Other foods that are good sources of magnesium are nuts and seeds, and whole grains. Drinking water can account for another 10% of your magnesium (if it has not had its minerals removed by processing). Legumes, fruit, meat and fish have moderate amounts. Dairy, while high in calcium is low in magnesium.
Magnesium is absorbed in your gut and is mostly (50–60%) stored in the mineral component of your bones. There is currently no reliable evidence to indicate that magnesium can be absorbed into your blood and tissues via transdermal application.
Of all the dietary magnesium you consume, between 24–76% is absorbed by your gut, and the rest is excreted. How much you absorb is determined by how much your body needs in order to keep your magnesium stores adequate.
Decreasing levels of magnesium consumption
In wealthy, industrialised nations magnesium intake is decreasing because of:
- increasing reliance on refined foods, as the processing removes minerals
- consumption of processed, soft (demineralised) water and other drinks
- soil depletion from modern farming practices which have stripped minerals from the soil.
‘With the omnipresence of processed foods, boiling and consumption of de-mineralised soft water, most industrialised countries are deprived of their natural magnesium supply.’
Research in the United States found that 68% of adults consumed less than the recommended daily allowance (RDA) of magnesium, and 19% consumed less than 50% of the RDA.
Other factors can also deplete your magnesium stores – such as ageing, stress, overindulging in alcohol and caffeine, excessive sweating and some medications.
How can you tell if you are magnesium deficient?
It can be difficult to tell if you are deficient in magnesium. Around 99% of your body’s magnesium is stored in your bones, muscles and other soft tissues. Magnesium is tightly regulated by your body and only 1% is circulating in your intracellular fluid and blood, so blood serum tests are unlikely to provide much information about whether your body’s store of magnesium is adequate.
Weakness, tremors and twitching are the clinical signs of hypomagnesaemia (low magnesium), but these may only manifest if magnesium is becoming very low. Magnesium stores may be sub-optimal without any of these symptoms being present.
A layperson’s method of determining whether you are magnesium deficient is to take small and increasing doses of an oral magnesium supplement. As the body only absorbs the magnesium that it needs to fill up its stores, excess magnesium will remain in your digestive tract. As magnesium is hygroscopic (it attracts water), this can cause a laxative effect. If you start experiencing a laxative effect then ease back on your dose of supplement until symptoms resolve. In this way you ensure that you are ingesting an optimal amount of magnesium.
The role of magnesium supplements
The best source of magnesium is a balanced diet rich in leafy green vegetables, nuts, seeds and whole grains. There is also a role to be played by magnesium supplementation.
Many forms of Magnesium supplementation are available and different forms may suit you more than others. One to avoid is magnesium oxide which has extremely low bioavailability – absorption rates may be less than 5%. Other more readily bioavailable forms include magnesium citrate, lactate, chloride and sulphate.
It is very important to note, however, that people should obtain advice from a doctor before taking any dietary supplement. In particular, individuals who have any impairment of kidney function must seek medical advice before supplementing with magnesium.
 Wilhelm Jahnen-Dechent, Markus Ketteler; Magnesium basics. Clin Kidney J 2012; 5 (Suppl_1): i3-i14. doi: 10.1093/ndtplus/sfr163
 King DE, Mainous AG 3rd, Geesey ME, Woolson RF. J Dietary magnesium and C-reactive protein levels. Am Coll Nutr. 2005 Jun;24(3):166-71.