It is believed that a diet with too much salt has harmful effects on health and especially on the activity of certain cells. Thankfully, these harmful effects should disappear quickly.
Most people consume too much salt per day, between 9 and 12 grams instead of the less than 5 grams recommended by the World Health Organization. Yet this advice, if followed, can lower blood pressure and the risk of cardiovascular diseases, such as strokes and heart attacks. But researchers have recently discovered a new harmful effect of an excessively salty diet: disrupting the energy balance of immune cells, ultimately preventing them from functioning properly. Their study was published in the journal Circulation.
Sodium disrupts white blood cell activity
Five grams of salt contain two grams of sodium. Previous research has shown that high sodium concentrations in the blood can affect monocyte activation and function. Monocytes are a type of white blood cell involved in the destruction of viruses and bacteria. When they enter various tissues, they become macrophages. Macrophages also belong to the white blood cell family, more specifically they are phagocytes that help in immune defense. Disrupting the function of these cells by consuming too much salt can therefore affect an individual’s immune system. But until now, researchers knew this consequence without knowing exactly what was happening in the cells.
Salt disrupts the cells’ respiratory chain
In this new study, scientists first sought to understand the metabolism of immune cells exposed to high concentrations of salt. However, the adverse effects did not become apparent until three hours after salt ingestion. “This disrupts the respiratory chain, causing the cells to produce less adenosine triphosphate and consume less oxygen,” explains Sabrina Geisberger, lead author of the study. Adenosine triphosphate – or ATP – provides the energy needed for chemical metabolic reactions, cell division, and muscle strength. ATP is produced in organelles called mitochondria through cellular respiration, or the respiratory chain. And it is the latter that suffers from the consumption of salt and sodium, a substance that slows ATP production in mitochondria.
Unintentional consumption of salt also has harmful effects
To reach this conclusion, the researchers conducted two separate clinical trials. In the first study, participants – healthy men – supplemented their normal diet with six grams of salt in tablet form per day for 14 days. In the second, the scientists analyzed monocyte levels in the participants’ blood after eating a pizza from an Italian restaurant that contained ten grams of salt. Their results showed a decrease in mitochondrial activity in both experiments. This means that the effect of sodium on mitochondria occurs not only after a prolonged period of high salt consumption but also after a single consumption such as with a pizza.
Mitochondrial activity returns to normal after eight hours
The blood tests of the people who ate this Italian specialty showed that the effect was visible three hours after the meal, but eight hours later it had almost disappeared. This is good news and means that mitochondrial activity is not permanently inhibited, but only for a few hours after salt ingestion. Still, the researchers would like to continue their research to answer two more questions: What are the long-term effects of an overly salty diet on mitochondria? Does salt have the same effect on other cells? “Cardiovascular risk comes to mind first, but several studies have shown that salt can affect immune cells in different ways,” Markus Kleinewietfeld concludes. If such an important cell mechanism is disturbed over a longer period of time, this can have negative consequences and lead to inflammatory diseases of the blood vessels, the joints, and even to autoimmune diseases. The WHO estimates that 2.5 million deaths could be avoided annually if salt consumption worldwide were reduced to the recommended levels.