Immune system: more inflammation from too much salt?
Christiane Fux studied journalism and psychology in Hamburg. The experienced medical editor has been writing magazine articles, news and factual texts on all conceivable health topics since 2001. In addition to her work for, Christiane Fux is also active in prose. Her first crime novel was published in 2012, and she also writes, designs and publishes her own crime plays.
More posts by Christiane Fux All content is checked by medical journalists.Salt is essential for survival. Therefore, the body has developed ingenious mechanisms in order not to excrete too much of the precious substance. But there is further evidence that too much of it is unhealthy: It not only increases blood pressure, but also influences the function of immune cells.
The reason for this could already be a minimally increased sodium concentration in the blood, which causes high salt consumption. Because table salt consists of sodium and chloride, which dissolve in the watery environment of the blood.
The sodium can then penetrate certain immune cells that are constantly patrolling the blood - the so-called monocytes. They are the precursor cells of macrophages, whose job it is to swallow and digest pathogens, pollutants and dead body cells.
Sodium slows down the cell power plants
In the monocytes, however, the sodium ions slow down the work of the mitochondria. They are the energy suppliers of almost all body cells. A particularly large number of people sit where a lot of energy is used: in muscles, nerves, sensory cells and egg cells.
Under the influence of sodium, the metabolism of the so-called organelles slows down: "The respiratory chain is disturbed," explains Prof. Dominik Müller from the Max Delbrück Center for Molecular Medicine (MDC) in an interview with The cells then produce less adenosine triphosphate (ATP). This is the fuel that the cells need, for example, to produce proteins that, among other things, regulate the metabolism.
The scientists first discovered in the laboratory that the power of the cell power plants decreases under the influence of sodium. With increased salt intake, the ATP production of the mitochondria was reduced within hours. At the same time, their oxygen consumption decreased - a further indication that the cell power plants are not working optimally.
Activated phagocytes could intensify inflammatory processes
What the researchers observed: Because of the lack of energy, the monocytes mature differently than usual. But instead of being slowed down, as might be expected due to the reduced energy balance, the immune cells that have developed from them have become more aggressive: "The phagocytes whose job it is to Detecting and eliminating pathogens in the body was able to fight certain pathogens better, ”explains Müller.
Sodium balance: minor fluctuations, serious effects
This has also been confirmed outside the laboratory. In experiments with volunteers who, for example, ate six grams of salt in addition to their usual diet or ate a pizza that contained ten grams of salt, the researchers were able to observe the same effect.
Mitochondrial function recovers quickly
In the experiments, this effect only lasted a few hours. "That is a good thing. Because if there had been a long-lasting disruption, one would have to worry that the cells would only be supplied with energy to a limited extent over the long term, ”says Müller. The mitochondrial activity recovers again.
"We were surprised that even small fluctuations in the sodium balance have such serious effects," reports Müller. These are deviations that would be completely inconspicuous in medical examinations.
In search of biological benefit
The scientists do not yet know the reason for the phenomenon. But an earlier experiment suggests that the interaction between sodium and the immune system may have a biological advantage.
In people who suffered from a bacterially inflamed area of skin on one leg, the sodium concentration around the focus of inflammation was greatly increased. "But that was not the case in the same place on the other leg," reports Müller. The body can apparently control the sodium concentration in a targeted and selective manner.
“That could be an important regulatory mechanism,” said Müller. It is conceivable that the sodium concentration creates a microenvironment in the body in which bacteria can be better combated. The high sodium concentration could, for example, flip certain switches in the genome. In this way, special genes can be activated that upregulate the immune cells over the long term.
The downsides of the strong defense
More active immune cells - that sounds positive at first. But too strong immune activity also has its downsides.For example, it promotes chronic inflammatory processes, which among other things promote the development of cardiovascular diseases. In that case, the short-term disruption of mitochondrial function from a salty meal could potentially have long-term negative consequences.
"And the macrophages are not the only immune cells that are sensitive to salt," reports Müller. An experiment from 2013 showed that certain T cells that play a role in the development of autoimmune diseases are also activated by salt. It would be conceivable that a high-salt diet would also favor rheumatism or multiple sclerosis.
What happens with several salt meals a day?
So what happens when people eat high salty meals several times a day? Müller points out that salt was in short supply in the early days of human history. "Evolution has not prepared the body for us to eat so salty food," said Müller. However, he assumes that the amount of salt that a person tolerates, genetic or lifestyle-related, could be very different. Japan, for example, where people eat particularly salty food, is the country (after the city-state Hong Kong) with the highest life expectancy in the world.
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