In a recent book the WHO said well-documented deficiencies in the minerals could be linked with heart disease, bone disease, atherosclerosis, hypertension and other ailments and backed fortification in principle.
In a chapter on cardiovascular health and magnesium, the WHO stated: “Not removing magnesium from drinking-water, or in certain situations increasing the magnesium intake from water, may be beneficial, especially for populations with an insufficient dietary intake of the mineral.”
It said fortification had become a political issue. “How strong does the epidemiological and other evidence need to be before society acts to reduce a potential public health threat rather than await further evidence that such a threat is real? Such a decision is a political rather than a purely public health issue.”
It said the epidemiological and clinical evidence was strong enough to back fresh guidance being issued by international governments.
In the US, magnesium intakes are estimated at about 75 per cent of recommended daily dietary intakes of about 400mg for men and 300mg for women.
The Magnesium Online Library observed that fortifying bottled water was one way of making up the shortfall in the US, with levels there at about 5mg per liter compared to 20mg in other parts of the world.
The WHO said that because calcium and magnesium content varied so widely in bottled waters, labeling should be improved.
“With levels of total dissolved solids ranging from almost zero to several thousand milligrams per litre and with a similar variation in concentrations of essential elements, the public should have access to information on the mineral composition of bottled or packaged water.”
This idea also translated to municipal water supplies. “All suppliers of water, whether through a piped distribution system or packaged/bottled waters, should make available to the consumer information on the mineral content of their water in order to enable development of guidance to vulnerable subgroups.”