High-salt diet may harm liver

Updated about Jan 11, 2017

ISLAMABAD: It is well known that consuming too much salt is linked to high blood pressure. Now, a new study suggests it may also lead to liver damage in adults and developing embryos.

The new study, led by Jinan University in Guangzhou, China, is published in the Journal of Agricultural and Food Chemistry.

Our bodies need salt - the chemical name for which is sodium chloride - to carry out essential functions. For example, sodium ions help control the transport of water and carry electrical impulses in nerves.

However, according to the Centers for Disease Control and Prevention (CDC), most Americans consume too much sodium - most of it from salt. Excess sodium intake is linked to high blood pressure, a major cause of heart disease and stroke.

The average daily sodium intake for Americans aged 2 years and older is over 3,400 mg of sodium - more than double the 1,500 mg limit recommended by national dietary guidelines for most American adults.

Most of the salt people consume in the US does not come from the salt shaker - it is already in food by the time it reaches the table - it comes from processed foods and foods prepared in restaurants. So, while asking people to reduce salt intake has some effect in that they can look at labels to pick lower salt products, there is also a need to get producers to reduce sodium content of packaged and prepared foods.

Previous studies have already suggested that too much sodium can damage the liver. In the new study, the researchers wanted to look in more detail at what happens at the level of cells.

The team carried out experiments where they fed adult mice on a high-salt diet and exposed chick embryos to a salty environment.

The results showed that too much sodium led to a number of changes in the liver - such as misshapen cells, higher rates of cell death and lower rates of cell division - all of which can lead to liver fibrosis.

Liver fibrosis occurs when there is excessive accumulation of "extracellular matrix" proteins like collagen that support the cells that do the work of the liver - such as breaking down old and damaged cells and metabolizing fats for energy.

The researchers suggest the mechanism through which too much salt may cause liver damage and fibrosis in both adults and developing embryos is through oxidative stress.

Oxidative stress is where the balance between the production of reactive oxygen species (free radicals) and antioxidants is upset in favor of the former. Such an imbalance can increase inflammatory cells and promote the death of liver cells, leading to progressive fibrosis.