Before you trust a man," goes an ancient proverb, "eat a peck of salt with him." That would take nearly nine months, for by modern measure a peck is equal to eight quarts, and an average-sized adult needs only six grams – about a thimble full of salt – each day to maintain a body chemistry that normally contains three ounces of salt.
We lose salt daily through urination and perspiration. If it isn't replaced, our bodies try to gain an optimum saline balance by discharging the excess water. Ultimately the body dehydrates until it dies of thirst. That is a problem only in underdeveloped countries today; elsewhere, and especially in the United States, the presence of too much salt in prepared foods appears to be a major threat to health, although scientists and health professionals still disagree on the extent of the problem.
The Corps of Discovery probably got plenty of salt from the bloody red meat they ate – about six pounds of it per man per day when they were faring well – from the "marrow bones" they relished, and from the salt they used for flavoring, when they had it. When meat was scarce and they were out of sodium chloride, and were obliged to rely on camas and wapato roots, they longed for the tang of it, but their bodies may also have sensed a chemical deprivation. Savor may have been a metonymy for need.
On the other hand, too much salt is fatal, too. Seawater is 3.5% salt, but human tolerance stops at 2%. If a person drinks seawater, the body sets about evacuating the excess salt through vomiting, diarrhea, and urination, leading to dehydration and, inevitably, death from thirst made more torturous by salt saturation.
In early November of 1805 a couple of the Corps' landlubbers began to discover this for themselves over on the north shore of the brackish Columbia River estuary. "Some of the party not accustomed to Salt water," Clark wrote, "has made too free a use of it. On them it acts a pergitive."
Even sea life is susceptible to too much salt. In 1998 a spill of salt-brine waste from the Mitsubishi Corporation's huge industrial salt works in Baja California killed many fish and black sea turtles.