Take it with a grain of salt.

(Chemfusion).(history and health aspects of the use of salt)

(Brief Article)

 

Canadian Chemical News; 4/1/2002; Schwarcz, Joe

 

The processed food industry loves salt. Sodium chloride is cheap, allows water to be retained, acts as a preservative and enhances flavor. As one salt promoter says, "salt is what makes things taste bad when it isn't in them." True enough. The human craving for salt may partially be explained by our physiological need for sodium. Without it, our nerve cells can't transmit electrical impulses, our muscles can't contract properly and our body fluids go out of kilter. So it shouldn't come as a surprise that 'salty' is one of the basic human tastes. But salt does more than just add 'saltiness' to food, it can also modify the way we perceive the other common tastes, namely sour, bitter and sweet.

Salt inhibits bitterness and can enhance sweetness. That's why you'll find salt in such unlikely foods as chocolate, apple pie and breakfast cereals. Indeed, studies have shown that consumer acceptance drops dramatically when salt levels in processed foods decline. That would explain the popularity of foods such as dill pickles, hot dogs, sauerkraut, vegetable juices, cottage cheese, olives, canned soups and pizza which can have up to a gram of salt per serving. It isn't hard to see how the recommended intake of six grams a day can be exceeded!

Salt was the first seasoning used by our ancestors. They got it by evaporating seawater, or by mining it. The origin of salt deposits in the ground can also be traced back to oceans which no longer exist, so that basically all salt is 'sea salt.' Salt was mined near Salzburg ('The City of Salt') in Austria as early as 6500 B.C. and the ancient Romans built large evaporation ponds by the sea to collect salt. In fact the Romans prized salt so much that soldiers were given a special allowance, known as the 'salarium' to purchase it. Our word 'salary' of course derives from this Latin expression. Salt was deemed so important that spilling it was thought to foster bad luck by attracting malevolent spirits. Tossing a little salt over the shoulder was the antidote! The grains of salt were supposed to lodge in the spirit's eyes and distract him from the evil he was planning. Spilled salt as an omen of bad things to come was an enduring belief. Da Vinci s 'Last Supper' clearly shows an overturned salt container in fro nt of Judas, foreshadowing his betrayal of Jesus.

It wasn't only for its taste that salt was so prized. It was also for its preservative value. When the salt concentration outside a bacterial or fungal cell is higher than inside it, water is drawn out of the cell to reduce the outside salt concentration. This process of 'osmosis dehydrates the cell and eventually destroys it. That's why salt was commonly rubbed into wounds to reduce the chance of bacterial infection. Of course this also disturbs tissue cells and causes the irritation we associate with 'rubbing salt into a wound.' Meat used to be preserved by soaking it in a brine solution or by covering the surface with whole grains of salt which were known as "corn," hence the origin of corned beef.

Perhaps the most unusual use of salt as a preservative was devised in 17th century England when heads of executed villains were put on public display to deter other criminals. The problem was the heads would quickly rot and attract birds which would strip off the flesh leaving behind a clean skull, which apparently was less frightening. The answer to this little problem was to boil the heads in salt water so they would not putrefy!

These rogues were salted after death. But what about the possibility of salting bringing on death? Our body tries to maintain a certain concentration of sodium in the blood. If the amount of sodium rises, more water has to be retained to maintain the same concentration. This means that the blood volume increases and that there is more blood for the heart to pump around the body. The pressure the blood exerts against the walls of the arteries increases and this can lead to strokes and heart attacks. But if less sodium is taken in, less water is retained, and blood pressure should go down. "Go easy on the salt," is the physician's advice if high blood pressure has been diagnosed.

Numerous studies have shown that about fifty percent of these patients respond to a low sodium diet. Why not all of them? Because in reality the situation is more complicated than just a simple balance between sodium and water. Calcium and potassium play important roles as well. In fact many researchers now believe that increasing potassium and calcium intake is as important as reducing sodium intake for people suffering from high blood pressure. This means more skim milk, more bananas, more oranges.

Joe Schwarcz, MCIC is the director of McGill University's Office for Chemistry on d Society. You con contact him at joe.schwarcz@mcgill.ca.

While no one disputes the low-sodium diet for people with high blood pressure, experts bicker when it comes to making recommendations for the public at large. Some say that asking everyone to try to reduce their salt intake from about nine to six grams a day is not based on science. I think they are wrong. Many people have undiagnosed high blood pressure and would benefit from reduced salt intake. Experiments with chimps have shown that as salt in the diet is increased, blood pressure goes up. Human epidemiologic al studies have shown the same thing. Populations with low salt intake have lower blood pressure. The Yanomani Indians of Brazil add no salt to their food and hypertension is unknown, in spite of being surrounded by poisonous snakes, bugs and researchers constantly wanting to measure their blood pressure. By contrast, North Americans with their penchant for salty hot dogs, chips and pizza are in the midst of a hypertension epidemic. Whether a reduced salt diet lowers blood pressure in people who do not have high pressure to start with is irrelevant. Eating fewer salty processed foods automatically leads to a healthier diet. I'm sure that spokespeople for the influential Salt Institute, an organization which promotes the use of salt, will dispute this. But I would take their comments with a grain of salt.

COPYRIGHT 2002 Chemical Institute of Canada

The above article is from Canadian Chemical News, April 1, 2002.

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