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Sodium’s Effects on the Immune System

Sodium, primarily consumed through our diet in the form of salt, but also in things such as laxatives and in toothpaste, has a variety of effects on the human body. We've probably all heard that too much salt can increase our risks for diseases, but one particular effect that remains still relatively uncertain is ts effect on the immune system.

Image is courtesy of Very Well Fit.

What happens if we get too much or too little sodium?

Consuming too much of anything is usually problematic, but salt, in particular, has been linked to increased chances of developing other diseases, such as high blood pressure, according to Live Science. Additionally, it has also been shown to correlate with incidences of stroke, heart failure, osteoporosis, stomach cancer, and kidney disease.

However, the University of Michigan explains that salt is needed by the body as it serves as an electrolyte and mineral, which allows it to maintain water levels in the inner and outer parts of the cell. Having low amounts of sodium (also known as hyponatremia), which can occur from kidney failure, or consumption of too many fluids can become especially dangerous as it can result in brain dysfunction, according to Merck Manual.

How is sodium related to immune cell function?

Through its direct and indirect effects on immune cells, sodium is now being recognized as a possible regulator of inflammatory and autoimmune illnesses. In a study published by Nature Reviews Nephrology, researchers examined the negative and positive roles that sodium could have on the immune system. They found that innate and adaptive immune cells can detect excessive sodium in the interstitium, a fluid-filled gap between cell barriers, altering their development and/or function.

Sodium could contribute to protective immunity, for example, by increasing host responses against skin diseases, or it may contribute to autoimmune imbalance and accelerate the development of cardiovascular and autoimmune illnesses, depending on the inflammatory setting. As proof of this, a study from the University of Bonn saw that mice that were given high sodium diets suffered from fatal bacterial infections, and humans that ate an added six grams of salt per day displayed increased immune deficiencies.

The reason behind this was because the decrease in granulocytes that attack parasitic bacteria decreased significantly after the high salt diet was introduced. "We were able to show this in mice with a listeria infection," explains Dr. Jobin. "We had previously put some of them on a high-salt diet. In the spleen and liver of these animals we counted 100 to 1,000 times the number of disease-causing pathogens." As a result, urinary tract infections had a slower time healing in these mice.

In the blood and numerous organs, the body maintains a rather constant salt concentration; consequently, vital biological processes would be disrupted if this salt concentration changed. Thus, salt is filtered through kidneys, in which a chloride sensor activates this excretion function. However, as an unfavourable side effect, this sensor causes an increase in glucocorticoids, which renders granulocytes, the most common type of immune cell in the blood, inactive. In fact, cortisone, the most well-known glucocorticoid, has traditionally been used to suppress inflammation. In the study, excessive salt consumption resulted in increased glucocorticoid levels in humans who volunteered, which likely led to a suppressed immune system.

More is definitely needed to be known about the subject of sodium's effect on the human body. Professor Dr. Christian Kurts, from the Institute of Experimental Immunology at the University of Bonn, stresses that an examination of high sodium diets on the entire body will grant researchers the ability to observe its effects properly.

Article authors: Idil Gure, Valerie Shirobokov

Article editor: Sherilyn Wen