The word salt is thought to come from the Latin sal, meaning salt. The English word "salary", which is similar in several European languages, is linked to the fact that salt was once a currency (legal tender) in many parts of the world.
Salt is a chemical compound called sodium chloride, with the formula NaCL (Na = sodium, CL = chlorine). Sodium chloride consists of 40% sodium and 60% chlorine.
Salt is of low toxicity and is non-flammable. Seen under a microscope, table salt is made up of many cube-shaped crystals.
Contents of this article:
What is salt used for?
Salt exists naturally in seawater. When an area of seawater becomes enclosed it evaporates under the sun, a deposit is left. Over millions of years other sediments have been deposited over the salt, leaving beds of halite (rock salt) below the surface.Salt used to be used just as a diet supplement and as a means of preserving food. Later, salt was used in such processes as tanning, dyeing and bleaching.
Relatively more recently, salt has been used for glazing pottery, soap-making and the early manufacture of chlorine. Today salt is widely used in the chemical industry, and also for water softening.
Why the human body needs salt
Not only does salt help control your fluid balance, it also controls the way your muscles and nerves work. Our bodies automatically regulate how much salt, or sodium, there is present. If levels are too high we get thirsty and drink - this speeds up the elimination of salt through our kidneys.
How much salt do we need?
According to the American Heart Association (AHA)1, sodium consumption should not exceed 1.5g per day (3.75g of salt), and that even includes healthy people without high blood pressure, diabetes or cardiovascular diseases.
AHA's chief executive officer, Nancy Brown said "Our recommendation is simple in the sense that it applies to the entire U.S population, not just at-risk groups. Americans of all ages, regardless of individual risk factors, can improve the heart health and reduce their risk of cardiovascular disease by restricting their daily consumption of sodium to less that 1,500 milligrams."
The AHA recommendation was published in the journal Circulation (November 5th, 2012 issue).2
According to the Food Standards Agency (UK)3, the human Guideline Daily Amount (GDA) should be:
- Age 11 years and over, 6g per day (2300 mg sodium)
- Age 7-10 years, 5g per day
- Age 4-6 years, 3g per day
- Age 1-3 years, 2g per day.
Infants under 1 year should not be given salt because their kidneys are not matured.
How much is 6g of table salt?
This is about one teaspoonful - not much. About three-quarters of the salt we eat is already in the food we buy.It is impossible to work out exactly how much salt you eat in one day without knowing the precise salt content of each food and measuring the exact quantities you eat.
However, knowing that a recommended daily maximum is 6g is useful, because you can then find out how much salt there is in some of the foods you normally eat.
Most people are surprised at how much salt they eat when they sit down and work it out from the foods they are consuming.
More potassium and less salt may lower blood pressure and stroke risk
If people consumed more potassium and less salt, millions of lives would be saved worldwide each year, researchers reported in the BMJ (British Medical Journal).4
If your potassium levels are too low there is a greater risk of a rise in blood pressure. According to The American Heart Association5, "potassium is important in controlling blood pressure because potassium lessens the effects of sodium."
The World Health Organization (WHO) aims to reduce salt intake globally to approximately one teaspoon (5 to 6 grams) per person per day by 2025.6
The difference between salt and sodium
Salt is sodium chloride (sodium plus chlorine). The sodium in the salt is what you have to look out for. 40% of salt is sodium.
If sodium is listed on the label's nutritional information instead of salt you have to multiply the amount by 2.5 to get the equivalent salt content. For example, if a portion of food contains 1g of sodium per 100g, you will know it contains 2.5g of salt per 100g.
Reading food labels
You should check the labels of foods to find out which ones are high and low in salt content. If the label has more than 1.5g of salt (or 0.6g of sodium) per 100g it is a high salt content food.
If it has 0.3g of salt (0.1g of sodium) per 100g then it is a low salt content food. Anything in between is a medium salt content food.
- High salt content food = 1.5g of salt (or 0.6g of sodium) per 100g
- Medium salt content food = between the High and Low figures
- Low salt content food = 0.3g of salt (0.1g of sodium) per 100g.
The amount you eat of a particular food decides how much salt you will get from it.
Doctors say we should try to avoid consuming foods that have a high salt content. It is a good idea to select, whenever possible, foods that say "no salt added".
UK traffic light labels
Some UK supermarkets and manufacturers have traffic light colors on the front of the pack. They are designed to help you glance at products and make quick decisions.
- High (red) = eat less amounts of these
- Medium (amber) = these are mostly OK
- Low (green) = these are definitely a healthier choice
How do I know how much salt a portion of food has?
Look at the label. If it says, for example, 1g of salt per 100g, and you consume 500g, you will get 5g. If the label specifies sodium, multiply the amount by 2.5.
Recent developments on high and low salt foods from MNT news
More salt in US diet comes from bread and rolls, not salty snacks. More salt in the average US diet comes bread and rolls and not from salty snacks like potato chips, pretzels and popcorn, according to a report from the Centers for Disease Control and Prevention (CDC).7
The science behind intake recommendations
The Food Standards Agency (FSA) advice for salt consumption for adults and children is based on the recommendations of the SACN (Scientific Advisory Committee on Nutrition). SACN is an independent expert committee that advises the FSA and the DoH (Department of Health, UK).
In 1994 COMA (Committee on Medical Aspects of Food and Nutrition Policy) in its report - Nutritional Aspects of Cardiovascular Disease8 - recommended reducing the average salt consumption of the UK population to 6g per day. The recommendation was based on an association between high salt intake and hypertension (high blood pressure).
SACN reviewed the evidence since 1994. In 2003 SACN concluded that the evidence indicating a link between hypertension and high salt intake had, in fact, increased since 1994.
The evidence indicated that current UK salt consumption increases the risk of developing hypertension - which can raise the risk of stroke and premature death from cardiovascular disease.
SACN confirmed that people would benefit from reducing their salt consumption to 6g per day maximum. Recommended daily consumption limits for babies and children were also lowered.
Alan Jackson, Chair of SACN, said "Meeting these targets would be of major benefit to public health. Even a small reduction in salt intake could help to reduce the burden of high blood pressure on our population."
He added that the maximum salt consumption targets were achievable, and not ideal or optimum intake levels.
According to the FSA, the best way to reduce hypertension is to follow a diet that is low in salt, total fat and saturated fat, and high in vegetables, fruit and low-fat dairy products.People who maintain a healthy body-weight, do not consume too much alcohol, and are physically active are much less likely to suffer from hypertension, says the FSA.
A study by Bibbins-Domingo and colleagues9 estimated that for the US population more than 800,000 life years could be saved for each reduction of 1 gram of salt.
How salt can affect health
Studies have indicated that too much salt consumption is linked to health problems, such as hypertension (high blood pressure) and osteoporosis. If you suffer from hypertension you would benefit from consuming less salt.
Very young children, very elderly people, as well as people with kidney disease cannot excrete sodium and regulate body fluid efficiently.
Scientists from Deakin University, Burwood, Australia, found that kids who consume salty foods tend to seek out an accompanying sugary drink. They reported their findings in the journal Pediatrics (December 2012 issue).10
This combination of salty foods and sugar-sweetened drinks could make it more likely that a child becomes overweight or obese.
If salt consumption were reduced, the authors wrote, perhaps children's desire for sugar-sweetened drinks would be less, resulting in better body weight control.
The researchers added that fluid intake was also linked to salt consumption - the more salt children ate, the more fluids they drank. Sugary drinks also tend to raise fluid intake.
Kids in the USA consume nearly as much salt as adults do11, the CDC (Centers for Disease Control and Prevention) informed in September 2012 in a report. The authors added that high salt consumption increases the risk of childhood hypertension.
Recent developments on how salt can affect your health from MNT news
Too little salt may be bad for some people. Researchers from the University of Glasgow in Scotland carried out a study which suggests that too little chloride, a component found in salt, may raise the risk of mortality and heart disease in people suffering from high blood pressure.12
Too much salt may overactivate the immune system, causing autoimmune diseases. Researchers from the Massachusetts Institute of Technology reported in the journal Nature that excessive consumption of salt might increase our risk of developing multiple sclerosis, allergies, lupus and other autoimmune diseases.131415
Study suggests salt might be nature's antidepressant. According to Kim Johnson, University of Iowa, rats that are deficient in salt shy away from activities they normally enjoy, like drinking a sugary substance or pressing a bar that stimulates a pleasant sensation in their brains. The researchers say that Evolution might have played an important part in the human hankering for salt.16