How salt weakens the power plants of our cells

When Sabrina Geisberger talks about the awarding of the Marthe Vogt Prize for young female scientists, she goes into raptures: She met many impressive women there; researchers who want to make a difference with their work. Geisberger herself was honored at the ceremony last fall for her work on the effect of salt on our immune system. Soon her findings will find their way into textbooks, expects Thomas Sommer, Scientific Director of the MDC. Here, the biochemist answers five questions about salt, health and the value of cooking for yourself.

Ms. Geisberger, your study on the consumption of salty foods published last year generated a huge media response. Even eating one pizza could destroy our immune system, it said. I've eaten considerably more than one pizza in my life, so is my immune system at a standstill?

No, don't worry. Our food doesn't have that power, even if some tabloids made it sound that way. But salt can actually upset the energy balance of our immune cells. This is because it dampens respiration and thus the activity of the mitochondria, i.e., the power plants in our cells. Our immune cells then suffer from a lack of energy, so to speak. This has doubly fatal consequences, because the immune cells perform two functions in our body, to put it very simply: Some fend off newly attacking viruses, parasites and bacteria, others control this killing and thus prevent inflammation. With excessive salt consumption, the defending cells are strengthened, but the regulating cells are weakened, which is why inflammation can develop more easily.

Are these long-term effects or does our immune system already react so sensitively to individual meals?

We did not know that until now. That is why we conducted two studies at the Max Delbrück Center together with the Charité in Berlin: On the one hand, we examined cell cultures from male volunteers who had increased their salt intake over a period of two weeks. On the other hand, we analyzed the blood values of participants after eating a pizza. This showed that even this one meal was enough to weaken the metabolism of our immune cells. The extent to which shocked me.

Why?

Because we did not work with grotesquely excessive salt values: We fed the test subjects a completely normal pizza, from the Italian restaurant around the corner, at eight in the morning, by the way (laughs). But this pizza alone contained a total of ten grams of salt. In contrast, a maximum of six grams per day is recommended. However, many people's eating habits hardly allow for this: In Germany, we often consume between eight and ten grams of salt a day, in other words, far too much, partly because of the hidden salt in many foods. It is true that the salt is washed out of the body again after a few hours. In the case of pizza, for example, it was no longer detectable in the blood after eight hours, which is why a single pizza is not a problem for us as long as we otherwise eat a healthy and balanced diet. However, the fact that we usually eat the next salty meal just a few hours later is a cause for concern. This can lead to an overall salt level that is too high.

What health consequences are to be feared as a result of this constant burden on the immune system?

Conceivable are, for example, heart and kidney damage, joint inflammation and autoimmune diseases. At the same time, we must assume that such processes naturally take place not only in the immune cells, but that an excess of salt also affects the metabolism of other body cells, for example, in the intestine or in the vascular walls. However, the details still need to be researched.

What advice do you have for people who want to take personal countermeasures? Does low-salt cooking help, for example?

When we cook ourselves, we usually only consume small amounts of salt. The problem is more with convenience foods: Frozen foods, bagged soups, but also foods like bread, cheese and cold cuts. So it's best to cook as much as possible yourself, from fresh ingredients. Of course, you can also salt them slightly, after all, the body needs salt, for example, for the elasticity of the cells or for signal transmission. But we should do our best to avoid an excess of salt.