Eating too salty a diet weakens your immune system and makes it harder for your body to fight bacterial infections, a study found.
Researchers at Bonn University Hospital fed mice a high-salt diet and found that they contracted more serious bacterial infections
Then, they gave human volunteers six grams of extra salt every day – about the same as two fast food meals – and found they developed immune deficiencies.
The World Health Organization says that people should consume no more than 0.17 grams of salt per day, which is equivalent to about one teaspoon.
Studies in Germany have shown that many people regularly exceed the WHO-recommended teaspoon of salt in their diet, putting their health at risk.
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Eating and firing a hamburger twice a day will drastically reduce your immune system’s ability to fight bacterial infections, the study found. Stock image
Figures from the Robert Koch Institute suggest that men consume an average of 0.4 grams of salt per day and women more than 0.3 grams.
Christian Kurts, from the University of Bonn, said their new study proves that excessive salt consumption weakens an important part of the immune system.
The findings are surprising, as earlier research seemed to show the opposite, according to Kurts.
For example, infections with certain skin parasites in laboratory animals heal considerably faster if they follow a low-salt diet.
Macrophages – immune cells that attack, eat and digest parasites – are particularly active in the presence of salt.
Several physicians concluded from the observation of macrophages that sodium chloride generally has an immune enhancing effect.
The lead author of the new study, Dr. Katarzyna Jobin, from the University of Wurzburg, said, “Our results show that this generalization is not correct.”
She said that the body keeps the salt concentration in the blood and in the various organs largely constant, otherwise an important biological process would not work.
The only major exception is the skin, which functions as the body’s salt reservoir.
This is why the extra sodium chloride intake works so well for some skin conditions – but not the body in general.
However, other parts of the body are not exposed to the extra salt consumed with food. Instead, it is filtered out by the kidneys and excreted in the urine.
The kidneys have a sodium chloride sensor that activates the salt excretion function.
This sensor also causes so-called glucocorticoids to build up in the body, which inhibits the function of many types of immune cells in the blood.
Granulocytes, like macrophages, are a capture cell, but attack bacteria rather than parasites. If they don’t do this, infections are much more serious.
‘We have been able to demonstrate this in mice with a listeria infection. Some of us had previously been on a low-salt diet, ”Jobin said.
“In the spleen and liver of these animals, we counted 100 to 1,000 times the number of pathogenic pathogens.”
Figures from the Robert Koch Institute suggest that men consume an average of 0.4 grams of salt per day and women more than 0.3 grams. Stock image
Listeria are bacteria that occur in contaminated food, for example, and can cause fever, vomiting and sepsis.
“We examined human volunteers who consumed six grams of salt in addition to their daily intake,” says Kurts.
“This is about the amount that is in two fast food meals, for example two burgers and two servings of chips.”
After a week, the scientists took blood from their subjects and examined the granulocytes, discovering that immune cells were much worse off with bacteria after they started eating a salt-rich diet.
Professor Kurts added, “Only through whole-body studies could we uncover the complex control circuits that lead from salt intake to this immunodeficiency.
“Our work therefore also illustrates the limitations of experiments purely with cell cultures.”
The study is published in the journal Science translational medicine.
WHAT SHOULD A BALANCED DIET LOOK LIKE?
Meals should be based on potatoes, bread, rice, pasta, or other starchy carbohydrates, ideally whole wheat, according to the NHS
• Eat at least 5 servings of a variety of fruits and vegetables every day. All fresh, frozen, dried and canned fruits and vegetables count
• Base meals on potatoes, bread, rice, pasta or other starchy carbohydrates, preferably whole wheat
• 30 grams of fiber per day: This is the same as eating all of the following: 5 servings of fruits and vegetables, 2 whole-grain cereal biscuits, 2 thick slices of whole-wheat bread and large baked potato with the skin on
• Have some dairy or dairy alternatives (such as soy drinks) choose less fat and less sugar
• Eat some beans, legumes, fish, eggs, meat and other proteins (including 2 servings of fish per week, one of which should be greasy)
• Choose unsaturated oils and spreads and consume in small amounts
• Drink 6-8 cups / glasses of water a day
• Adults should have less than 6 g of salt and 20 g of saturated fat for women or 30 g for men per day
Source: NHS Eatwell guide