Question: What happens if you don't have enough salt in your system?

Keith Siew answered on 17 Jun 2013:

Hi mlam & ssimo,

So the thing to remember is… where salt goes water follows. I’m sure you’ve covered osmosis at some point or other. Essentially water will move from a place of low solute (i.e. salt) concentration to a place of high concentration. So you’re body needs salt to be able to keep the water in the body.

But healthy kidneys have an amazing ability to respond to extremely low salt diets, the kidney conserves the salt it has by reabsorbing almost all of it from the filtered blood and preventing its loss in the urine and excessive water loss so they can maintain a normal blood pressure. However, for example in our genetically modified mice they’ve lost the ability to control the salt reabsorption… so they lose a lot of salt in their urine. Some people have a condition called Gitelman’s Syndrome who have a similar mutation to the mice I study. These people have naturally low blood pressure and if they don’t have enough salt in their diet they can develop dangerously low blood pressure.

But salt, specifically sodium [Na], is important in many other cell process and low levels in the body can cause big problems! Your nerve cells depend on specific concentrations of sodium (and other elements like calcium, Ca; chloride, Cl; and potassium, K) inside and outside of the cells to generate a “potential difference” or voltage across the membrane of the cell. This means that there is more positively charged particles on one side of the membrane and more negative on the other. So sodium for example has a positive charge Na+ and chloride has a negative Cl-. So when the cell wants to generate an electrical pulse to send a signal, lots of different channels and transporters activate to move these positive and negative particles across the membrane to create this. The same thing happens in your heart muscles too… so having too low salt in addition to having lower blood pressure could also affect the hearts ability to beat and reduce the ability of the nervous system to send signals around the body.

Hope that answers your question!