You may know that sodium is a mineral you need to maintain cellular health and well being – in fact, so is chloride. Table salt, or sodium chloride, is a source of both these essential minerals. You use sodium and chloride in the process of digesting other compounds, as well as elsewhere in the body.
Sodium is a metallic element, but you won't encounter pure metallic sodium in nature because it's very reactive. Instead, sodium occurs in nature in the form of various salts. These are compounds of positively-charged particles of sodium chemically combined with negatively-charged particles of other elements or compounds. One common sodium salt is sodium chloride; other common sodium salts include sodium bicarbonate, which is baking soda, and sodium hydroxide, or lye.
Chloride is the chemical name for negatively-charged particles of chlorine, which is an element. You don't generally encounter elemental chlorine – a toxic green gas – in nature, though you'll often find chloride in compounds. Aside from sodium chloride, perhaps the most well recognized of the chloride compounds is hydrochloric acid, or HCl. This is a common industrial acid and is the acid produced by cells in your stomach.
Digestion of Food
Though you don't need to digest sodium chloride that you consume, sodium and chloride in your body help you to digest and absorb the nutrients you eat. Though you depend in great part upon digestive enzymes to help you break down your food, stomach acid is also important to the process of digestion. You need chloride in your bloodstream to produce the HCl secreted by stomach cells, explains Dr. Lauralee Sherwood in her book "Human Physiology."
The sodium from sodium chloride and other sources is critical to your ability to absorb monosaccharides and amino acids – the building blocks of carbohydrates and proteins, respectively – from the small intestine into your bloodstream. When you consume carbohydrates and proteins, you digest them into their building blocks. The intestinal cells then move them into the bloodstream. This process requires the presence of sodium, since sodium activates the transporter proteins that shuttle the building blocks across the intestinal lining, explains Dr. Gary Thibodeau in his book "Anatomy and Physiology."