Sodium

(43%) - which acts as a reserve -, in the connective tissue and in the cartilage.

The metabolism of sodium is closely correlated with that of potassium; while the first cation, as we have said, is mainly found in body fluids external to the cell, potassium is particularly concentrated in intracellular fluids.

and extracellular fluid: if present in excessive concentrations, it draws, for reasons of osmosis, considerable quantities of water, causing edema and hypertension (due to the increase in blood volume); on the contrary, in the presence of sodium deficit, there is to a decrease in the volume of blood and interstitial fluid;

It forms electrochemical gradients at the level of the cell membrane, which are very important for the transmission of the nerve impulse, for muscle contraction and for cellular exchanges (nutrients, ions, water, etc.);

It regulates the acid / base balance.

, called ileus. Excess is eliminated in the urine and, to a lesser extent, in sweating and faeces. In particular conditions, such as profuse sweating or in the presence of diarrhea, the extra renal sodium losses can still become conspicuous.

The kidney is the main regulator of sodium metabolism; considering the considerable importance of this mineral, numerous organs and chemical messengers also participate in this process. Among these, the best known is undoubtedly aldosterone, a hormone produced by the adrenal cortex which increases the reabsorption of sodium and the elimination of potassium ions. Another hormone with similar activity is vasopressin, while the atrial natriuretic peptide acts in the opposite way, facilitating sodium excretion and water loss.

In blood plasma, sodium normally reaches concentrations of 140 mEq / l. We speak of hyponatremia or hyposodemia when the amount of sodium in the blood falls below the norm. Generally caused by particular endocrine disorders or by the abuse of diuretics, hyponatremia causes anorexia, nausea, vomiting and, in severe cases, coma and death.

When non-physiological increases in sodemia are recorded, we speak of hypernatremia; this condition can be caused by over-intake of sodium and / or excessive loss of liquids (diarrhea, diabetes, profuse sweating, etc.): it determines arterial hypertension which, in the most serious cases, can lead to heart failure.

, without the need to add salt to dishes.

Sodium is particularly abundant in cured meats and other foods to which it is added to increase shelf life (capers, bottarga, etc.) and flavor (anchovies, cheeses, snacks, potato chips, snacks, olives and other foods preserved in brine).

In general, foods of animal origin (milk, meat, poultry and fish) are richer in sodium than foods of plant origin (cereals, vegetables, vegetables and fruit).

To learn more, consult the table: the foods richest in sodium.

it contains on average 0.4 g of sodium.

In case of chronic overdose, this mineral appears to play an important role in the onset of hypertension, but also, to a lesser extent, in osteoporosis (it increases renal excretion of calcium).

The mechanism by which sodium induces a hypertensive state has not yet been fully understood, but it is known that its excessive consumption, typical of industrialized societies, causes an increase in blood pressure with advancing age. The risk of getting this disease further increases if the diet is both high in sodium and low in potassium, a mineral found in fruit (both fresh and dried) and vegetables.

Better to reduce sodium but not eliminate it, especially in summer

Sodium restrictions, obtained through a diet without added salt or by replacing it with low-sodium dietary salts, are often prescribed to hypertensive patients. On the other hand, it should be emphasized that a ruthless war against sodium does not find many justifications in the preventive sphere.

Although it is important to reduce the addition of salt to foods, already from the pediatric age to educate the child's palate, a chronic removal of salt from one's table could have negative implications, especially for those who practice sports.

If the loss of salts during physical activity are not restored through the consumption of isotonic drinks, the risk of hyponatremia can in fact become real. In particular, when the losses of liquids are filled by drinking abundantly the much advertised low-sodium water ( generally with a low fixed residue), the blood increases in volume, diluting even more the already reduced blood concentrations of sodium. The result of this behavior, typical of water intoxication, can be very serious and even lethal. Exemplary is the case of an "athlete who died of hyponatremic encephalopathy during the Boston marathon after drinking 15 liters of fluids during the 5-6 hours of competition.

In addition to the risk of a sodium deficiency, the chronic removal of salt from one's diet can lead to iodine deficiencies (which have largely been solved by adding this mineral to table salt).