The following is adapted from the forthcoming book, “The Art and science of Low Carbohydrate Living” by Jeff S. Volek, PhD, RD, and Stephen D. Phinney, MD, PhD
Whole books have been written about the history of salt. Wars were fought over access to salt. Roman soldiers were often paid with a measure of salt, hence the origin of the English word “salary”. Hunters and their prey, herders and their cattle, all shaped their actions and habits around access to salt.
The reason, of course, is that salt (sodium) is necessary for life.
Humans did not need to know chemistry to understand the value of salt. Salt deprivation leads to lightheadedness, fatigue, headache, and malaise. Aboriginal cultures could figure out that if they drank from one spring they began to feel lousy, but if they drank from that other one, they’d feel OK. The Inuit knew which ice to melt for water to boil their meat. Sea ice loses its salt content with age. Fresh ice had too much salt, fresh snow had none, whereas older seas ice was just right.
Today we “know” that too much salt is bad for us, so why this long discussion of a discredited nutrient?
The short answer is that the amount of carbohydrate in our diet changes our need for salt.
High carbohydrate diets make the kidneys retain salt, whereas a low carbohydrate intake increases sodium excretion by the kidney. Hunting cultures seemed to understand this, and thus their highly evolved practices of finding sodium and consuming enough of it to maintain health and well-being.
The body’s metabolism of salt is uniquely different when one is adapted to a low carbohydrate diet.
Salt and water are more efficiently excreted, which is a good thing as long as you maintain an adequate minimum sodium intake.
Ignore this lesson and you are likely to suffer the completely avoidable problems of headache, fatigue, weakness and constipation—maladies that any Inuit healer would have promptly resolved by giving you a bowl of blood soup, or meat broth made with sea ice of the proper age.