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What Does Sodium Do in the Body?

author image Sheri Kay
Sheri Kay has a master's degree in human nutrition. She's the co-author of two books and has been a nutrition and fitness writer since 2004.
What Does Sodium Do in the Body?
A close-up of sea salt on a wooden table. Photo Credit: dianazh/iStock/Getty Images

Your body needs sodium to maintain blood pressure and for normal nerve and muscle function. Getting too much sodium might cause blood pressure problems that can lead to health problems. It's easy to get enough sodium from the foods you eat and, in fact, it's more likely that you're getting more sodium than you need.

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Fluid Balance

Sodium is an electrolyte, which means it has an electrical charge. Your body needs electrolytes to control blood pressure and blood volume. Your kidneys remove excess fluid from your blood by osmosis, which is a process by which fluid is drawn across cell walls. A specific level of sodium, along with another dietary mineral called potassium, is necessary so that excess fluid is drawn out of the bloodstream -- through the blood vessel walls and into collecting ducts in the kidneys. The extra fluid is removed as urine.

Muscle and Nerve Function

Sodium is essential for electrical impulses to travel along nerves and for muscle function. It's part of the sodium-potassium pump found in the membranes of cells. Sodium is pumped out of the cells, and potassium is pumped into the cells, creating an electrical charge that leads to the transmission of impulses along nerves. The sodium-potassium pump is also necessary for muscles to contract.

Getting Enough Sodium

You don't need a lot of sodium to perform these functions, and getting too much might put the electrolytes out of balance. The adequate intake for sodium is set at 1,500 milligrams per day for adults up to 50 years of age; 1,300 milligrams for adults from ages 51 to 70; and 1,200 milligrams per day after that. Sodium is found naturally in most of the foods you eat, at least in small amounts, with much larger amounts in soy sauce and processed foods. Processed foods are high in sodium if they contain salt for flavoring or sodium benzoate or sodium phosphate as preservatives.

Too Much Sodium

According to the University of Maryland Medical Center, getting too much sodium might cause elevated blood pressure in some people, and it might cause fluids to build up in the tissues of people with congestive heart failure, cirrhosis of the liver or kidney disease. High blood pressure can put a strain on your kidneys, arteries, heart and brain. The UMMC suggests healthy adults should limit intake to 2,300 milligrams per day, and people with high blood pressure should stay below 1,500 milligrams per day.

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