Salted_ A Manifesto on the World's Most Essential Mineral, With Recipes - Mark Bitterman [18]
The opposite of hyponatremia is hypernatremia, an excess of sodium in the blood. This is caused not by excessive sodium in the body (though drinking seawater can cause it), but by an insufficient amount of water for your body to use to regulate itself. The slightest elevation of sodium levels in the body triggers powerful thirst sensations, making hypernatremia extremely uncommon. It occurs most often among the elderly, who lack the ability to get water when thirsty, or less commonly among infants, the severely mentally impaired, or people taking diuretics. Fatigue and confusion are followed by coma and death if hypernatremia is not treated.
Like sodium, the element chlorine is essential to your body. Chloride (an ion of chlorine) is the primary negatively charged ion in extracellular fluid, and sodium the main positively charged ion. Chloride, like sodium, serves the body as an electrolyte, enabling the electrical signals that allow muscle and nerve tissues to function. It also regulates the blood’s ability to carry carbon dioxide out of the cells and out of the body through respiration. It helps the blood maintain a healthy pH balance and is essential to neurotransmitter function in the brain; chlorine plays a role in protein digestion, as a component of pepsin.
Chlorine is an essential component in the manufacture of the sanitizing agents the body uses to protect itself from contamination. This includes hydrochloric acid, which is the fluid in our stomach that plays a primary role in sterilizing and breaking down the food we eat. Chlorine also allows the body to produce hypochlorite, a disinfectant that the immune system relies on to battle infections.
SODIUM AND CHLORINE: THE DYNAMIC DUO
The two most abundant elements in salt are chlorine and sodium. Sodium is the sixth most abundant element in the earth’s crust. It is an odorless metal with a rather luscious, light silvery sheen to it, and it is strangely pliant—in fact, soft as butter. Its chemical symbol is Na, after its Latin name, natrium. On the surface it seems pleasant enough, but it’s really one of the most terrifying substances imaginable.
While you could cut metallic sodium with a butter knife, you would be very unwise to spread it on bread and eat it. Elemental sodium is incredibly reactive, and some of the substances it reacts most violently with are acids, alcohols, oxygen, carbon dioxide, and water. We are mostly water.
If you were to touch sodium, it would cause severe burns in reaction to the moisture on your skin; it could even ignite, causing a very serious deep tissue injury. If you were to swallow it, it would react with the water in your saliva and possibly explode. And it can cause severe respiratory trauma if inhaled.
Sodium catches fire when exposed to moisture and oxygen in the air. Once burning, it can burn violently enough to explode. Due to sodium’s low melting point (about 208°F), sodium explosions tend to be accompanied by the spattering of molten sodium. If you were to attempt to douse burning sodium with water, highly explosive hydrogen gas would result.
Metallic sodium is used to prepare organic compounds and is essential for manufacturing esters—fruity compounds used in many artificially flavored foods and synthetic fragrances. It is part of sodium hydroxide (also called caustic soda or lye), which is in most industrial soaps, dyes, and cleaning agents and is commonly used to neutralize acids.
Chlorine is even more dangerous. Chlorine’s chemical symbol is Cl; it exists normally as the gas Cl₂. At high concentrations, chlorine is corrosive and irritating to all body