High blood pressure, diseased kidneys and weakened bones: Too much salt can be bad for your health. Now a study shows that the immune system also suffers.
No more than five grams per day: according to the current recommendation of the World Health Organization, it should not be more salt – for several good reasons. Sodium chloride – the chemical name – drives up blood pressure and thus increases the risk of stroke and heart attack, as numerous studies have already shown. It was also already known that the kidneys are strained by too much salt and that the microbiome in the intestine changes.
Nevertheless, according to data from the Robert Koch Institute, many people in Germany consume significantly more than recommended: According to this, women consumed an average of eight grams a day in 2021, and men even ten grams.
If you reach for the salt shaker too often or too often heavily salted ready-made products or fast food, you will also throw your immune system out of balance. Among other things, too much salt inhibits the work of the scavenger cells (mitochondria) that are important for the immune system, as a study published in 2020 in the journal “Science Translational Medicine” was able to show:
In mice that were fed with particularly high-salt food, bacterial infections were significantly more severe. And human study participants who took in six grams of salt a day also showed a demonstrable weakening of the immune system.
Too much salt: immune system turns against the body
However, an excess of sodium chloride can also lead to the immune system overreacting and falsely directing the defense mechanisms against its own organism, as is the case with autoimmune diseases such as multiple sclerosis (MS). This is indicated by a study now published in the specialist journal “Cell Metabolism”.
Regulatory T cells – also known as Tregs – play an important role: they ensure that the immune system is downregulated again after successfully fighting an infection. So they slow down our immune system again at the right time.
When this mechanism is disrupted, autoimmune diseases can develop, resulting in inflammation and tissue damage.
What is the salt concentration in the body?
The concentration of salt in the blood and human organs normally remains constant for relevant biological processes to function smoothly. Extra sodium chloride ingested with food is filtered out by the kidneys so that it is excreted in the urine. The concentration only fluctuates in the skin, which can store salt. That’s one reason sodium chloride helps with some skin conditions.
Oversalting inhibits important part of the immune system
In order to check whether too much salt can inhibit the regulatory T cells, the researchers involved set up cultures with human T cells in the laboratory and examined the influence of increased salt content in the nutrient medium on the work of the mitochondria and on gene activity in the Tregs has.
In fact, the scientists observed that the mitochondria of the Tregs produced less energy. This in turn led to a weakened function of the immune cells. “We have now been able to prove for the first time that excessive salt intake also weakens an important arm of the immune system,” says Prof. Dr. Christian Kurts from the Institute for Experimental Immunology at the University of Bonn, one of the authors.
Findings also interesting for research on cancer
The authors of the study explain why a high salt content restricts the work of the mitochondria: “The high extracellular salt content increases the concentration of sodium ions in the cell.” This inhibits the respiration of the mitochondria because it disrupts their electron transport chain and ultimately leads, among other things, to a lack of energy in the T cells.
According to the scientists, the findings can strengthen the understanding of which factors lead to the regulatory T cells no longer functioning correctly. These not only play an important role in autoimmune diseases, but also in cancer and cardiovascular diseases.
However, further studies are needed to analyze the connections with diseases in more detail.
