The decision by the German Federal Institute for Risk Assessment (BfR) takes into account new data that found no diarrhoea cases observed with magnesium intakes of 250 mg or less per day in addition to magnesium consumed in the diet.
"Food supplements are in vogue, and many people believe that they can provide health benefits," said BfR president Dr Andreas Hensel.
"But the consumption of food supplements may also be associated with health risks. The best nutritional strategy is a balanced and varied diet with plenty of fruit and vegetables.
“Such a diet supplies a healthy body with all essential substances. In most cases, therefore, food supplements are superfluous."
The BfR added that the recommended maximum intake only applied to adults and children aged four and above. A lack of data explained why levels could not be determined for those below that age.
The decision also applies to magnesium salts such as magnesium chloride, sulphate, aspartate, lactate or magnesium oxide via dietary supplements, water or fortified foods.
Additional advice suggested the maximum magnesium level be split into at least two or more doses per day, as this was said to improve tolerability.
Risk profile details
BfR’s risk profile (Opinion No. No. 034/2017) calculated a ‘possible’ likelihood that the general population would be at risk of a health impairment if adults took one daily magnesium does of 360 mg of magnesium in food supplement form.
The seriousness of the health impaired in adults was classed as ‘light (reversible)’ and advised consumer avoidance.
As well as collating results of recent human studies, the BfR also took additional direction from the European Food Safety Authority’s (EFSA) predecessor, the Scientific Committee on Food (SCF), who also identified an Upper Intake Level (UL) for magnesium of 250 mg.
A consensus as to what constitutes a safe magnesium level varies throughout Europe.
In 2001, the SCF (2001) had identified mild diarrhoea as a primary undesirable effect that occurred with excessive additional magnesium intake of approximately 360/365 mg of magnesium per day.
It was a finding shared by a panel of the Norwegian Scientific Committee for Food Safety, which in 2016, recommended a UL of 350 mg magnesium in food supplements per day in adults over 18.