Home' Salt : Salt Contents 150 the salt book
But as life on land evolved---in hot humid climates and with a herbivorous diet---
there was much less available salt. So we adapted a complex physiology to conserve
body sodium, and developed an appetitive response to sodium in foods, encouraging
us to consume foods that contained sodium. And these mechanisms, which developed
over millions of years in a vastly different food environment, remain with us today.
Salt for Survival
The average salinity of blood and other intercellular fluids is around 0.9%, and the
body of an average adult contains around 250 grams of sodium chloride. Without it,
quite simply, we would die, and as the body constantly loses salt through bodily
functions, it must be replaced.
Sodium, a mineral that the body cannot manufacture for itself, is vital for trans-
mitting electrical impulses through the nerves, assisting muscle contraction and
controlling the distribution of water in the body. Chloride is essential for digestion,
supplies the basis of the hydrochloric acid in the stomach's gastric juices, and
enhances the ability of the blood to carry carbon dioxide from respiring tissues
back to the lungs.
Sodium and chloride---along with a host of other elements, including zinc, iron,
potassium and magnesium---are essential to both life and health. But the amounts
are remarkably small: the Yanomamo Indians of the Brazilian rainforest, famous
for the miniscule amounts of salt they consume, reportedly survive on less than half
a gram of salt per day. If that is all the human body needs to survive, then it does not
quite explain why from the beginning of civilisation salt has been one of mankind's
most sought-after commodities.
The simple answer is that salt preserves. It draws from food the moisture that would
support bacteria, and is itself an anti-bacterial agent. Whether in curing meats or
pickling or fermenting vegetables, salting was the predominant method of preserv-
ing food from before recorded history until the mid 1920s, when Clarence Birdseye
perfected his technique of snap-freezing food and General Electric produced the first
It was, we might say, the beginning of a new ice age. It was also the end of salt as a
necessary food preserver.
Since the end of the last great ice age, when people first domesticated animals,
cultivated vegetables and learned to harvest the fields of wild grain that appeared in
the wake of the retreating ice, our salt requirements have grown continuously. With
a diet which was now largely vegetables and grains, and only occasionally the meat
of domestic animals, men and women needed more salt to eat. They needed salt for
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