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Take it with a pinch of salt |
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Written by Robert Smith
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Wednesday, 18 February 2009 |
Eating an egg for breakfast in peace is not always easy given the common admonition, "Don't use so much salt!"
While high consumption of table salt has long been blamed for high blood pressure, some scientists are now not so sure.
Beyond dispute, however, is that the human body's fluid balance and absorption of nutrients depend on salt, which maintains osmotic pressure in the lining of blood vessels, explains Stephan Bischoff, a professor of nutritional medicine at Hohenheim University in Germany.
Salt thus enables the passage of nutrients into cells - and of waste out of them. It is also important in areas including the transmission of nerve impulses, muscle movement and bone density.
"Salt also causes the body to retain water," Bischoff says, pointing out that a salt deficiency could lead to dehydration.
An adult requires a daily minimum of 1.4 grams of salt to compensate for the salt lost normally by the body. Sweating or diarrhea can greatly raise the requirement. "Sweat contains between 0.8 and 1.3 grams of table salt per liter," notes Karl-Ludwig Resch, professor of physical medicine and rehabilitation at Dresden University.
Generally speaking, a person's salt intake exceeds the minimum daily requirement many times over.
Salted meat products such as sausage and salami - 100 grams of the latter contain about 3.1 grams of salt - are not the only sources. Among the saltiest foods are some varieties of cheese.
"Processed foods, and particularly canned foods, are also very high in salt," says Professor Walter Zidek, director of the Nephrology Clinic at Berlin's Charite University Hospital.
So how much salt is healthy? The question is not easy to answer. The standard given by the Bonn-based German Nutrition Society (DGE) is 6-10 grams daily for adolescents and adults.
"Exceeding this amount could lead, in individual cases, to negative consequences for health," says DGE spokesperson Antje Gahl.
The guarded phrasing reflects the fact that salt intake is no longer automatically linked to high blood pressure or hypertension.
"There has been no reliable study proving that the average salt intake in the healthy population contributes to high blood pressure," Resch says. He believes there are many possible causes of high blood pressure and "many ways to lower it, too", among which reducing the consumption of table salt is one of the least effective.
According to Resch, simply gaining four or five kg affects blood pressure two to three times more than anything achievable by reducing salt intake.
There are no uniform recommendations on how much salt a person should consume. While Zidek says a diet low in salt would do no one any harm, Resch advises against a strict low-salt diet.
"A healthy person with fairly normal blood pressure need not worry about salt consumption," Resch says.
Nonetheless, nutritionists are agreed on one thing: A diet rich in fresh foods and low in processed ones would seem to be the safest bet.
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