Everyone needs salt for fluid balance and muscle and nerve function. But too much salt is bad for us, we hear. So how much do we need?

The human body regulates how much sodium it contains. If levels are too high, we get thirsty and drink, and the kidneys speed up the process of getting rid of it.

Too much sodium has been linked to kidney stones, high blood pressure, and cardiovascular disease.

Too little sodium can lead to hyponatremia, and symptoms of dizziness, confusion, muscle twitches and seizures.

Most Americans consume too much salt and sodium, due to a high intake of processed, restaurant, and convenience foods. How far should we go in cutting out salt?

What we know as salt is really sodium chloride. It is 40 percent sodium and the rest is chlorine.

Fast facts about salt

  • The body needs salt, but too much or too little can cause problems.
  • Sodium makes up 40 percent of salt. If a food label lists sodium instead of salt, multiply the answer by 2.5 for an accurate picture of the salt content.
  • Most Americans take in too much salt, and 75 percent of it is hidden in processed and packaged food.
  • The American Heart Association (AHA) recommend a maximum intake of no more than 2.3 grams (g) or 2,300 milligrams (mg) of sodium a day, or around 1 teaspoon, and preferably no more than 1,500 mg.
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Sodium, which comes from salt, can help to maintain certain functions, but too much can be harmful. Salt contains 40 percent sodium. For every 10 grams (g) of salt we eat, 4 g is sodium.

The word salt comes from the Latin word “sal,” meaning salt. It was once a valuable commodity, and it has been used as a currency for trading. The English word “salary” comes from the word salt.

Salt has long been used for flavoring and for preserving food. It has also been used in tanning, dyeing and bleaching, and the production of pottery, soap, and chlorine. Today, it is widely used in the chemical industry.

It commonly features at the table or in the kitchen as free-flowing table salt, rock salt, sea salt, or kosher salt. High levels of salt, or sodium, come hidden in everyday foods, from fast food to frozen chicken.

The body uses sodium to maintain fluid levels. A balance of fluid and sodium is necessary for the health of the heart, liver, and kidneys. It regulates blood fluids and prevents low blood pressure.

Too little salt

Low sodium levels can result if there is too much fluid in the body, for example, because of fluid retention. Diuretics are given in this case, to reduce fluid retention.

Other causes of low sodium in the body include:

  • Addison disease
  • a blockage in the small intestine
  • diarrhea and vomiting
  • an underactive thyroid
  • heart failure
  • drinking too much water
  • burns

If sodium levels fall in the blood, this affects brain activity. The person may feel sluggish and lethargic. They may experience muscle twitches, followed by seizures, a loss of consciousness, coma, and death. If sodium levels fall quickly, this may happen very fast.

In older people, symptoms can be severe.

One study found that when rats were deprived of sodium, they kept away from activities that they normally enjoyed. The researchers suggested, therefore, that sodium could act as an antidepressant.

Too much salt

Excess sodium intake has been linked to health problems, such as osteoporosis, kidney disease, and hypertension, or high blood pressure, which can lead to cardiovascular disease and stroke.

The American Heart Association (AHA) explain that when there is too much sodium in the blood, it “pulls more water into the bloodstream.” As the volume of blood increases, the heart has to work harder to pump it around the body. In time, this can stretch the walls of the blood vessels, making them more susceptible to damage.

High blood pressure also contributes to the buildup of plaque in the arteries, leading to a greater risk of stroke and heart disease, among other problems.

The AHA urge people to consume more potassium at the same time as reducing their sodium intake. Potassium is believed to lessen the negative effects of sodium.

Sodium has also been shown to overstimulate the immune system, suggesting a link with autoimmune diseases such as lupus, multiple sclerosis, allergies, and other conditions.

Researchers have found that children who consume salty foods are more likely to have a sugary drink with it. The combination could increase the risk of obesity.

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Snacks that are high in salt hide 75 percent of dietary salt. Aim to cut down on salty and processed foods.

Salt and sodium occur naturally dissolved in seawater, or as a crystalline solid in rock salt.

The salt we eat today comes largely from the processed and convenience foods in our diet, but some natural and unprocessed foods also contain salt or sodium. It occurs naturally in meats, seafood, eggs, some vegetables, and dairy products.

The top six salty foods in the United States (U.S.), according to the AHA, are:

  • breads and rolls
  • cold cuts and cured meats
  • pizza
  • soup
  • sandwiches
  • poultry

Sea salt, rock salt, and kosher salt all contain around 40 percent sodium by weight. They may contain additional potassium and other minerals but in tiny amounts. All types of salt should be used in moderation.

How much salt?

The average American currently eats more than 3,400 milligrams (mg) or 3.4 grams (g) of sodium every day. Salt is 40 percent sodium, so that is around 8,500 mg or 8.5 g of salt.

The AHA and the World Health Organization recommend not exceeding a daily sodium intake of 1,500 mg, or 1.5 g a day, or just over half a teaspoon of table salt.

People with high blood pressure, diabetes or cardiovascular diseases should be especially vigilant in keeping their intake below the 1,500 mg threshold.

What does 1,500 mg of sodium look like?

  • one egg: up to 140 mg
  • 230 g of fresh milk: around 50 mg
  • 200 g of plain yogurt: 40 mg
  • 200 g of natural, low-fat yogurt: 76 mg
  • 50 g of raw celery: 140 mg
  • 60 g cooked spinach: 120 mg

Other vegetables are low in sodium, but canned vegetables have added salt and a far higher sodium content.

Dietitians urge people not to add extra salt to their food because enough is already added, if it is processed or packaged.

Infants under one year should not be given salt because their kidneys are not matured.

It is difficult to measure how much salt we are consuming, as it is hidden in many foods. More than 75 percent of salt eaten by Americans does not come from the salt shaker.

It is important to check the nutritional information on processed food to find out which ones are high and low in salt, or sodium, content, and what is the difference between salt and sodium.

Salt is 40 percent sodium, so, if a nutrition label lists sodium instead of salt, you must multiply the amount by 2.5 to get the equivalent salt content. If 100 g of food contains 1 g of sodium, the salt content of that food will be 2.5 g.

This may be an unnecessary, however, step since health recommendations use milligrams of sodium, not salt, as a reference.

How low is ‘low’?

The U.S. Food and Drug Administration (FDA) recommend that people look carefully at low-salt claims on packaging.

If a serving contains 1,400 mg (1.4 g) or less of sodium per serving, the salt and sodium content is classed as “low.”

A food with a high-sodium content is one that contains more than 20 percent of the recommended daily intake, or more than 480 mg (0.48 g) per serving.

If a food is salt- or sodium-free, for example, it can contain up to 5 mg (0.005 g) of sodium per serving. Terms such as “light” or “reduced” sodium do not necessarily mean little salt, but that there is less salt than the regular product per serving.

Doctors recommend avoiding foods with a high salt content, and, if possible, selecting those with “no salt added.” You will get plenty of salt from fresh meat, vegetables, and dairy produce.