A Magnesium Story

Magnesium is currently available in a number of formulations including different types of organic and inorganic salts. Each salt contains a specific percentage of Magnesium.

For example, MgSO4 7H2O  is a particular type of Mg salt usually administered intravenously to treat severe hypomagnesemia. Its MW is 246.5, and its percentage of Mg content is 9.7% (Mg atomic mass is 24, since MgSO4 contains only 1 atom of Mg, the relative percentage of Mg is 24/246.5*100=9.7). Thus 1 g of MgSO4 contains 97 mg of Mg i.e. 4 mmol.

Mg content of different Mg Salts:


MgSO4 9.7%
Mg citrate 16%
Mg pidolate 8.7%
MgCl2  12%
MgO 60%
Mg lactate 12%
Mg piruvate 10%
Mg orothate 7.7%
Mg gluconate 5.8%


In adults, the recommended daily intake of Mg i.e. the daily intake level of Mg that is considered to be sufficient to meet the requirements of 97–98% of healthy individuals is equal to about 400 mg.

When used to treat hypomagnesemia, maintenance therapy may require the oral administration of 60-720 mg of Mg usually as magnesium oxide (400 mg two or three times daily) magnesium gluconate (500 mg two or three times daily), magnesium chloride or magnesium lactate.

It's important to remember that the total amount of Mg administered is only one of many players involved in oral supplementation. Thus the story is more complex than it could appear on a first glance...

Another important player is Mg bioavability which may deeply influences Mg absorption: for example, Mg absorption from Mg citrate is significantly higher than Mg absorption from Mg oxide. Indeed, as a general rule, Mg organic salts are better sources of Mg than Mg inorganic salts. One study has showed the fractional absorption of magnesium oxide to be as low as 4%.

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A few notes on currently available Mg formulations in Italy:

Preparazioni disponibili in Italia con la dose relativa per una quantità pari a circa 100% della RDA

Mg Pidolato (Mag2) fl 1.5 g -> Mg 122 mg o 5 mmol dose: 3 fl/die
Mg Pidolato (Mag2) bust 2.25 g-> Mg 184 mg o 8 mmol dose:2 bust/die
Mg(OH)2 45% -> 20 mmol/2.5 g di concentrato
MagB -> 2 cp=375 mg di Mg elemento (MgO in associazione con vitamine del gruppo B)
Magnesio Supremo/Phyto Garda Mg PG (Mg citrato e carbonato) 2 cucchiaini=430 mg
Maglife (pidolato, bisglicinato e glicerofosfato) 1 cps = 66 mg (dose: 2 cp x3/die)