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Table salt is our biggest source of two vital elements, sodium, and chlorine, in the form of chloride. While the conventional wisdom is that most of us get too much salt, the fact is, we could not live without both sodium and chloride.
Sodium is essential to life because of its positive charge. Cells use positively charged sodium ions to keep the electrical charge on their outer membranes just negative enough to attract amino acids and regulating hormones. They also use sodium to import water and glucose. Every time a cell uses insulin to receive one molecule of glucose, it also imports three ions of sodium.
The body uses chloride to regulate acid-base balance. Chloride helps the bloodstream regulate the balance between carbon dioxide and oxygen. It also is part of the activation of neurons.
Everybody needs salt. The question is how much. Most often we hear about excessive sodium in the context of high blood pressure.
Does Excessive Consumption of Salt Really Cause High Blood Pressure?
If you live in the United States and you have high blood pressure, chances are that your doctor has given you a handout on the DASH (Dietary Approaches to Stop Hypertension) diet. The idea behind the DASH diet is that if you don't eat as much salt, then your bloodstream doesn't have to carry as much water to dilute it, and your blood pressure won't be as high.
There are people for whom the DASH diet is a vital part of controlling high blood pressure, but these are people who have an underlying difficulty with sodium regulation. For most of us, kidneys keep tight control over sodium levels. People who go on extremely restrictive diets may only see a 1-3 mm Hg reduction in blood pressure, and sometimes sodium restriction causes hyponatremia, low sodium levels. However, there are a few people for whom reducing salt normalizes blood pressure. The same sort of relationship seems to hold for liver health.
High Sodium Levels and Liver Fibrosis
A series of studies have found that high-sodium diets accelerate a process in the liver known as fibrosis. When the liver is chronically injured, either by alcoholism, hemochromatosis (high iron levels), constant exposure to chemicals, or viral infection, it tends to create fibers. Too much salt causes some liver cells to absorb too much water and lose their characteristic shape. They may not adhere in tissues where they should, leaving them to be removed by the immune system. They may injure neighboring cells, triggering the production of scar tissue. Fibrous tissue in the liver can't break down food into nutrients or store glucose as glycogen for quick energy. It can't recycle hormones or detoxify chemicals in food or from the environment. The more salt in the bloodstream, the less functional liver cells become, and the worse the symptoms of liver disease become.
There's not a lot of room for doubt that people who consume the most sodium are the most likely to suffer fibrosis, which can lead to cirrhosis, of the liver. However, if you don't have a liver disease that leads to cirrhosis, then you probably don't need to restrict salt for your liver's health.