Many people in our country continue to think that tap water is inadvisable because its hardness -rich in calcium and magnesium- is excessive and promotes kidney stones, to the point that they refrain from drinking it.
In this regard, drinking hard water, according to the WHO classification, has between 10 and 500 milligrams of calcium carbonate equivalents per liter. For the WHO, the usual tolerance threshold, in terms of taste, ranges between 100 and 300 milligrams, although it points out that many consumers accept figures of up to 500 mg / liter without problems.
Hard water and stones; no evidence
In this article we have already explained that with the levels of lime in Spanish waters, and always placing ourselves within reasonable levels that the health authorities endorse, there was no promotion of kidney stones, although it is true that two of the types of Most important stones have calcium in their structure.
We are talking about calcium oxalate stone calculations, that they have to do with the reaction that oxalic acid forms with calcium, creating an insoluble salt that is deposited in the urinary ducts, and calcium phosphate stones that form in the kidney by giving rise to an insoluble salt between the acid phosphoric and calcium.
Oxalic acid is found in many plant-based foods, although it can be manufactured in considerable amounts by the kidney. As for phosphorus and calcium, it is obvious that they come from external sources, such as the foods and drinks that contain them, including water.
However, the reason stones form appears to be more linked to a genetic predisposition than to the mineral wealth of food and drinkyes In this way, the person with a genetic and metabolic tendency to form stones will suffer from them even if they have a balanced diet and, according to the conclusion a review of the World Health Organization (WHO), there is no visible relationship between drinking hard water and kidney stones.
In any case, the organization advises people who previously know or suffer from their tendency to form kidney stones to refrain from consuming excessively hard water.
Calcium and magnesium, essential for our health
On the other hand, it has been speculated that hard water is not only not harmful but, quite the contrary, it is healthy. The reason would be precisely its contribution in calcium and magnesium, two very important minerals for the human body, but especially from the age of 50, when its assimilation could progressively decrease.
Magnesium is of vital importance in the muscle at certain levels so that muscle contraction is well regulated. It also intervenes in the transmission of the electrical impulse in various ways.
Likewise, it is part of numerous coenzymes with important functions and participates in the reactions related to the production of adenosine triphosphate or ATP, the basic molecule for energy storage at the cellular level. And precisely for this reason it is essential at ages when the risk of heart attack increases.
On the other hand, the assistance of magnesium is necessary so that phosphorus and calcium are well fixed in bones and teeth. This means that foods rich in calcium and phosphorus but without magnesium are not effective in fixing these minerals. But accompanied by hard water, which also provides extra calcium, they can better fulfill their function and this would be reflected in better cardiovascular health and a lower incidence of osteoporosis in older ages.
The mean daily value of Necessary magnesium for our good health is around 400 milligrams. Although it is a high demand, with a varied and balanced diet it is easily achieved, since it is a very abundant element on the planet.
However, covering this dose can be difficult if our diet is based on food with a low nutritional profile or has many deficiencies, as well as if we stray too far from the Mediterranean diet. Sometimes older people have profiles of malnutrition; can hard water be a good supplement?
Magnesium: evidence, but weak
There are various studies and reviews that support this. Specifically one review of epidemiological studies on drinking water hardness and cardiovascular diseases concludes that “information from epidemiological and other studies supports the hypothesis that low magnesium intake may increase the risk of dying and possibly developing cardiovascular disease or stroke.”
“Thus,” the report continues, “not removing magnesium from drinking water or, in certain situations, increasing magnesium intake from water may be beneficial, especially for populations with insufficient dietary intake of the mineral.”
However, the WHO is cautious about this and in its review Effect of water hardness on cardiovascular mortality: an ecological time series approach warns that “ecological time series studies of populations exposed to changes in drinking water hardness may not provide conclusive evidence on links between water hardness and cardiovascular mortality unless very large populations are studied” .
Hard water, calcium and osteoporosis
On the other hand, a study by the Hospital Clinic of Barcelona in 2008 concluded that the consumption of hard water could have preventive effects against osteoporosis. In addition, the Spanish study of tap water Intake of calcium, magnesium and sodium through water: health implicationsalso from 2008, concluded: “On some occasions, water can even provide the minimum recommended amount of Ca(2+) and Mg(2+)”.
This is also certified by another state study entitled The calcium concentration of public drinking waters and bottled mineral waters in Spain and its contribution to satisfying nutritional needswhich supports that the consumption of tap water in many Spanish cities can supplement an insufficient intake of calcium in food.
In any case, there is no doubt that, except in very specific cases, among which are people with a well-known tendency to calculations or water that is very high in sodium, tap water is not harmful to health.
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