Salt doesn''t just make your food tastier—it''s actually required for life. Sodium ions help the body perform a number of basic tasks, including maintaining the fluid in blood cells and helping the small intestine absorb nutrients. We can''t make salt in our own bodies, so humans have always had to look to their environments to fill the need. Early hunters could get a steady supply of salt from meat, but agricultural groups had to seek it out by following animal tracks to salt deposits.
The ancient Egyptians were the first to realize the preservation possibilities of salt. Sodium draws the bacteria-causing moisture out of foods, drying them and making it possible to store meat without refrigeration for extended periods of time. Delicacies like our modern-day Parma hams, gravlax, bresaola and baccala are all the result of salt curing. But back in the day, this type of preservation wasn''t limited to meat: Mummies were packed in salt too. In fact, when mummies were shipped down the Nile as cargo, they were taxed in the "salted meat" bracket.
How did ancient populations get their salt? The Shangxi province of China has a salt lake, Yuncheng, and it''s estimated that wars were being fought over control of its salt reserves as early as 6000 B.C. Salt was gathered from the lake during the dry season when the water evaporated and flats of salt were exposed. The Egyptians got their salt from Nile marshes, while early British towns clustered around salt springs. In fact, the "wich" suffix in English place names like Middlewich and Norwich is associated with areas where salt working was a common practice.
Even well into American history, destinies were decided by salt. During the Civil War, salt was a precious commodity, used not only for eating but for tanning leather, dyeing clothes and preserving troop rations. Confederate President Jefferson Davis even offered a military service waiver to anyone willing to work on salt production on the coast. The ocean was the only reliable source of salt for the South since inland production facilities were so valued they became early targets of Union attacks.
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In common usage, salt is a mineral composed primarily of sodium chloride (NaCl). When used in food, especially in granulated form, it is more formally called table salt. In the form of a natural crystalline mineral, salt is also known as rock salt or halite. Salt is essential for life in general (being the source of the essential dietary minerals sodium and chlorine), and saltiness is one of the basic human tastes. Salt is one of the oldest and most ubiquitous food seasonings, and is known to uniformly improve the taste perception of food, including otherwise unpalatable food.[1] Salting, brining, and pickling are ancient and important methods of food preservation.
Some of the earliest evidence of salt processing dates to around 6000 BC, when people living in the area of present-day Romania boiled spring water to extract salts; a salt works in China dates to approximately the same period.[2] Salt was prized by the ancient Hebrews, Greeks, Romans, Byzantines, Hittites, Egyptians, and Indians. Salt became an important article of trade and was transported by boat across the Mediterranean Sea, along specially built salt roads, and across the Sahara on camel caravans. The scarcity and universal need for salt have led nations to go to war over it and use it to raise tax revenues. Salt is used in religious ceremonies and has other cultural and traditional significance.
The word salary comes from the Latin word for salt. The reason for this is unknown; a persistent modern claim that the Roman Legions were sometimes paid in salt is baseless.[27][28] The word salad literally means "salted", and comes from the ancient Roman practice of salting leaf vegetables.[29]
The amount of iodine and the specific iodine compound added to salt varies. In the United States, the Food and Drug Administration (FDA) recommends 150 micrograms of iodine per day for both men and women.[45] US iodized salt contains 46–77 ppm (parts per million), whereas in the UK the recommended iodine content of iodized salt is 10–22 ppm.[46]
In "doubly fortified salt", both iodide and iron salts are added. The latter alleviates iron deficiency anaemia, which interferes with the mental development of an estimated 40% of infants in the developing world. A typical iron source is ferrous fumarate.[3] Another additive, especially important for pregnant women, is folic acid (vitamin B9), which gives the table salt a yellow colour. Folic acid helps prevent neural tube defects and anaemia, which affect young mothers, especially in developing countries.[3]
A lack of fluoride in the diet is the cause of a greatly increased incidence of dental caries.[50] Fluoride salts can be added to table salt with the goal of reducing tooth decay, especially in countries that have not benefited from fluoridated toothpastes and fluoridated water. The practice is more common in some European countries where water fluoridation is not carried out. In France, 35% of the table salt sold contains added sodium fluoride.[3]
Salt is present in most foods, but in naturally occurring foodstuffs such as meats, vegetables and fruit, it is present in very small quantities. It is often added to processed foods (such as canned foods and especially salted foods, pickled foods, and snack foods or other convenience foods), where it functions as both a preservative and a flavouring. Dairy salt is used in the preparation of butter and cheese products.[56] As a flavouring, salt enhances the taste of other foods by suppressing the bitterness of those foods making them more palatable and relatively sweeter.[57]
Before the advent of electrically powered refrigeration, salting was one of the main methods of food preservation. Thus, herring contains 67 mg sodium per 100 g, while kipper, its preserved form, contains 990 mg. Similarly, pork typically contains 63 mg while bacon contains 1,480 mg, and potatoes contain 7 mg but potato crisps 800 mg per 100 g.[15] Salt is used extensively in cooking as a flavouring, and in cooking techniques such as with salt crusts and brining. The main sources of salt in the Western diet, apart from direct use, are bread and cereals, meat, and dairy products.[15]
In many East Asian cultures, salt is not traditionally used as a condiment.[58] In its place, condiments such as soy sauce, fish sauce and oyster sauce tend to have a high sodium content and fill a similar role to table salt in western cultures. They are most often used for cooking rather than as table condiments.[59]
Human salt taste is detected by sodium taste receptors present in taste bud cells on the tongue.[60] Human sensory taste testing studies have shown that proteolyzed forms of epithelial sodium channel (ENaC) function as the human salt taste receptor.[61]
The World Health Organization recommends that adults should consume less than 2,000 mg of sodium (which is contained in 5 g of salt) per day.[67] Guidelines by the United States recommend that people with hypertension, African Americans, and middle-aged and older adults should limit consumption to no more than 1,500 mg of sodium per day and meet the potassium recommendation of 4,700 mg/day with a healthy diet of fruits and vegetables.[6][73]
While reduction of sodium intake to less than 2,300 mg per day is recommended by developed countries,[6] one review recommended that sodium intake be reduced to at least 1,200 mg (contained in 3 g of salt) per day, as a further reduction in salt intake led to a greater fall in systolic blood pressure for all age groups and ethnicities.[68] Another review indicated that there is inconsistent/insufficient evidence to conclude that reducing sodium intake to lower than 2,300 mg per day is either beneficial or harmful.[74]
One of the two most prominent dietary risks for disability in the world are diets high in sodium.[76]
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