On this Wikipedia the language links are at the top of the page across from the article title. The minimum physiological requirement for sodium is between 115 and 500 milligrams per day depending on sweating due sodium in big mac meal physical activity, and whether the person is adapted to the climate. Some potent neurotoxins, such as batrachotoxin, increase the sodium ion permeability of the cell membranes in nerves and muscles, causing a massive and irreversible depolarization of the membranes with potentially fatal consequences. Since only some plants need sodium and those in small quantities, a completely plant-based diet will generally be very low in sodium.

This requires some herbivores to obtain their sodium from salt licks and other mineral sources. Sodium ions play a diverse and important role in many physiological processes, acting to regulate blood volume, blood pressure, osmotic equilibrium and pH. These fluids, such as blood plasma and extracellular fluids in other tissues, bathe cells and carry out transport functions for nutrients and wastes. Sodium is also the principal cation in seawater, although the concentration there is about 3.

8 times what it is normally in extracellular body fluids. Although the system for maintaining optimal salt and water balance in the body is a complex one, one of the primary ways in which the human body keeps track of loss of body water is that osmoreceptors in the hypothalamus sense a balance of sodium and water concentration in extracellular fluids. Severely dehydrated persons, such as people rescued from ocean or desert survival situations, usually have very high blood sodium concentrations. These must be very carefully and slowly returned to normal, since too-rapid correction of hypernatremia may result in brain damage from cellular swelling, as water moves suddenly into cells with high osmolar content.

In humans, a high-salt intake was demonstrated to attenuate nitric oxide production. Sodium and Potassium in Health and Disease”. In Astrid Sigel, Helmut Sigel and Roland K. Interrelations between Essential Metal Ions and Human Diseases.