(N.Morgan) The salt equation that doctors have been educated to believe for over 200 years is not hard to understand.
The body depends on this basic mineral for an assortment of capacities, including circulatory strain and the transmission of nerve motivations. Sodium levels in the blood must be painstakingly kept up.
On the off chance that you eat a great deal of salt — sodium chloride — you will end up plainly parched and drink water, weakening your blood enough to keep up the best possible centralization of sodium. Eventually you will discharge a great part of the overabundance of salt and water in urine.
The hypothesis is instinctive and straightforward. Also, it might be totally off-base.
New investigations of Russian cosmonauts, held in confinement to recreate space travel, demonstrate that eating more salt made them less parched yet in some way or another hungrier. Resulting tests found that mice consumed more calories when they got more salt, eating 25 percent more just to keep up their weight.
The examination, distributed as of late in two thick papers in The Journal of Clinical Investigation, repudiates a significant part of the tried and true way of thinking about how the body handles salt, and recommends that abnormal states may assume a part in weight reduction.
The discoveries have paralyzed kidney authorities.
“This is quite recently exceptionally novel and captivating,” said Dr. Melanie Hoenig, an aide teacher of medication at Harvard Medical School. “The work was fastidiously done.”
Dr. James R. Johnston, a teacher at the University of Pittsburgh, denoted each startling finding in the edges of the two papers. The reviews were secured with scrawls when he was finished.
“Really cool,” he said, although he added that the findings need to be replicated.
The new studies are the completion of a decades long journey by a dedicated researcher, Dr. Jens Titze, now a kidney master at Vanderbilt University Medical Center and the Interdisciplinary Center for Clinical Research in Erlangen, Germany.
In 1991, as a restorative understudy in Berlin, he took a class on human physiology in extraordinary situations. The educator who instructed the course worked with the European space program and displayed information from a recreated 28-day mission in which a group lived in a little container.
The fundamental objective was to figure out how the group individuals would get along. Be that as it may, the researchers likewise had gathered the space travelers’ pee and other physiological markers.
Dr. Titze saw something perplexing in the team individuals’ information: Their pee volumes went here and there in a seven-day cycle. That negated all he’d been educated in medicinal school: There ought to be no such worldly cycle.
In 1994, the Russian space program was chosen to do a 135-day recreation of life on the Mir space station. Dr. Titze orchestrated to go to Russia to study urine designs among the team individuals and how these were influenced by salt in the eating routine.
A striking finding developed: a 28-day cadence in the measure of sodium the cosmonauts’ bodies held that was not connected to the measure of urine they delivered. What’s more, the sodium rhythms were a great deal more articulated than the pee designs.
The sodium levels ought to have been rising and falling with the volume of pee. In spite of the fact that the review wasn’t impeccable — the team individuals’ sodium admission was not exactly aligned — Dr. Titze was persuaded an option that is other than liquid admission was affecting sodium stores in the team’s bodies.
The conclusion, he understood, “was heresy.”
In 2006, the Russian space program declared two more reenactment studies, one enduring 105 days and the other 520 days. Dr. Titze saw an opportunity to make sense of whether his atypical discoveries were genuine.
In the shorter reenactment, the cosmonauts ate an eating regimen containing 12 grams of salt every day, trailed by nine grams day by day, and after that a low-salt eating regimen of six grams day by day, each for a 28-day time frame. In the more extended mission, the cosmonauts likewise ate an extra cycle of 12 grams of salt day by day.
Like the vast majority of us, the cosmonauts preferred their salt. Oliver Knickel, 33, a German resident taking an interest in the program who is presently a car design in Stuttgart, reviewed that even the nourishment which provided 12 grams a day was not sufficiently salty for him.
At the point when the salt level got down to six grams, he stated, “It didn’t taste good.”
The genuine stunner came when Dr. Titze measured the measure of sodium discharged in the team’s pee, the volume of their pee, and the measure of sodium in their blood.
The strange benchmarks in urine volume remained, however everything appeared to continue as indicated by the course readings. At the point when the group ate more salt, they discharged more salt; the measure of sodium in their blood stayed steady, and their urine volume expanded.
“But then we had a look at fluid intake, and were more than surprised,” he said.
Instead of drinking more, the crew were drinking less in the long run when getting more salt. So where was the excreted water coming from?
“There was only one way to explain this phenomenon,” Dr. Titze said. “The body most likely had generated or produced water when salt intake was high.”
Another mystery: The group grumbled that they were constantly ravenous on the high-salt eating regimen. Dr. Titze guaranteed them that they were getting precisely enough sustenance to keep up their weights, and were eating a similar sum on the lower-salt eating regimens, when appetite did not appear to be issue.
Be that as it may, pee tests recommended another clarification. The group individuals were expanding creation of glucocorticoid hormones, which impact both digestion and safe capacity.
To get further understanding, Dr. Titze started an investigation of mice in the research facility. Beyond any doubt enough, the more salt he added to the creatures’ eating regimen, the less water they drank. What’s more, he saw why.
The creatures were getting water — however not by drinking it. The expanded levels of glucocorticoid hormones separated fat and muscle in their own particular bodies. This arranged for water for the body to utilize.
In any case, that procedure requires vitality, Dr. Titze likewise discovered, which is the reason the mice ate 25 percent more nourishment on a high-salt eating regimen. The hormones additionally might be a reason for the odd long haul vacillations in pee volume.
Researchers realized that a starving body will consume its own fat and muscle for sustenance. Yet, the acknowledgment that something comparative occurs on a salty eating routine has come as a disclosure.
Individuals do what camels do, noted Dr. Stamp Zeidel, a nephrologist at Harvard Medical School who composed an article going with Dr. Titze’s reviews. A camel going through the abandon that has no water to drink gets dilute rather by softening the fat up its protuberance.
One of the numerous ramifications of this finding is that salt might be included in weight reduction. By and large, researchers have accepted that a high-salt eating routine empowers a more noteworthy admission of liquids, which builds weight.
Be that as it may, if adjusting a higher salt admission requires the body to separate tissue, it might likewise expand vitality use.
Still, Dr. Titze said he would not instruct eating a considerable measure with respect to salt to get more fit. On the off chance that his outcomes are right, more salt will make you hungrier over the long haul, so you would need to make certain you didn’t gobble more sustenance to compensate for the additional calories consumed.
What’s more, Dr. Titze stated, high glucocorticoid levels are connected to such conditions as osteoporosis, muscle misfortune, Type 2 diabetes and other metabolic issues.
In any case, shouldn’t something be said about fluids? Everybody realizes that salty nourishments make you parched. How might it be that a high-salt eating routine made the cosmonauts less parched?
In reality, said Dr. Zeidel, people and animals get thirsty because salt-detecting neurons in the mouth stimulate an urge to drink. This kind of “thirst” may have nothing to do with the body’s actual need for water.
These findings have opened up an array of puzzling questions, experts said.
“The work suggests that we really do not understand the effect of sodium chloride on the body,” said Dr. Hoenig.
“These effects may be far more complex and far-reaching than the relatively simple laws that dictate movement of fluid, based on pressures and particles.”
She and others have not abandoned their conviction that high-salt diets can raise blood pressure in some people.
But now, Dr. Hoenig said, “I suspect that when it comes to the adverse effects of high sodium intake, we are right for all the wrong reasons.”