Salt Myths Salty food is not a thirst-trigger

A pinch of salt against thirst
Too much salty food endangers the health. In addition, you will quickly become very thirsty. The latter is apparently not true. Scientific research has shown that astronauts have even reduced their thirst for food by eating more salt - but hunger increased as a result.

Too much salt endangers your health
Doctors warn again and again: Salty food endangers the health. High salt intake can, among other things, lead to health problems such as hypertension and other cardiovascular diseases. In the long term, this increases the risk of heart attack and stroke. In addition, too much salt damages our immune system. And last but not least, salty food leads to a strong thirst. But the latter is apparently not true, as researchers now report.

Salty food increases the feeling of thirst. So the everyday experience. Scientists have now refuted this truism. An increased salt intake therefore does not lead to drinking more.
(Image: Andrey_Arkusha / fotolia.com)

Brood wisdom refutes
Chips and peanuts to nibble and already thirsty. Especially in front of the TV you can do this everyday experience again and again. The fact that you have to drink more of salty food is, according to scientists, a truism, which has now been refuted.

Two new studies show exactly the opposite.

How salt in food influences drinking behavior has never been tested in a long-term study, according to a statement by the Friedrich-Alexander University Erlangen-Nürnberg.

So far, it has only been known that more salt in the diet stimulates the production of urine. This additional liquid comes from drinks - so the thesis.

Experiments during simulated Mars mission
Not even close! says a research team from the German Aerospace Center (DLR), the Max Delbrück Center for Molecular Medicine (MDC), the University of Erlangen-Nuremberg, Vanderbilt University in the USA and other international colleagues.

They reviewed the ancient wisdom during a simulated Mars mission, and are now presenting their findings in the latest issue of the Journal of Clinical Investigation.

It turned out that "cosmonauts" who consumed more salt produced more water in the body, drank less and needed more energy.

Of course, salt has nothing directly to do with Mars. If people wanted to travel to the Red Planet, every drop of drinking water would be precious and a pinch of salt in the food should not jeopardize the mission.

However, the simulation was really interesting because it allowed strict control and measurement of nutrition, water and salt intake.

Dr. Natalia Rakova and her team from the Charité and MDC conducted two independent studies on ten male volunteers. The subjects were trapped in a spaceship dummy for either 105 or 205 days.

All participants had absolutely identical menus. Over the weeks, the research team then gradually changed the salt content in the diet.

Salt boosts your thirst in the short term
The experiment confirmed that salt boosts thirst in the short term. More salt in the food also leads to a higher salt concentration in the urine and a higher total amount of urine - that was not surprising.

But the greater amount of fluid was not from drinks. The subjects even drank less in total when they ate more salt. The salt triggered a water-saving mechanism in the kidneys.

Previously, the sodium and chloride ions that make up salt bind to water molecules and pull them into the urine. However, the new results showed that the salt remains in the urine while the water is transported back to the kidney and body.

This surprised the team around Jens Titze, professor at the University of Erlangen-Nuremberg and the Vanderbilt University Medical Center. "What could be the power that drives the water back into the body," he wondered.

More hunger through salty food
Tests on mice then showed that the substance urea (urea) could be involved. With the help of this substance, muscles and liver dispose of nitrogen. Urea accumulated in the mouse kidney, counteracting the water-binding power of sodium and chloride.

However, the synthesis of urea costs a lot of energy. Mice fed a saltier diet were more hungry, but no longer drank. Even the human "cosmonauts" who got salty food complained of hunger.

According to the scientists, the new findings make the role of urea appear in a new light. "Urea is not just a waste product, as we had previously assumed," said Prof. Friedrich C. Luft of the Charité and the MDC.

"Instead, it turns out to be a very important osmolyte - it's a compound that binds water and helps transport it. Urea holds the water in the body when we excrete salt. This restrains the water that would otherwise be carried through the salt into the urine. "

The balance of water in the body (water homeostasis) is also important for life here on Earth. "We need to see this process as a joint effort of the liver, muscles and kidneys," Titze said.

"In the study, we did not directly examine the influence on blood pressure and other aspects of the cardiovascular system. Their functions, however, are closely linked to water homeostasis and energy metabolism. "(Ad)