Sodium is not always bad for us. In small amount, it is an essential mineral to maintain balance of fluids. It also helps transmit nerve impulses and influences the contraction and relaxation of muscles.
Dairy products, meat, shellfish and vegetables contain the highest amount of natural sodium.
The World Health Organisation (WHO) recommends that adults consume less than 2,000mg of sodium (or 5g of salt) daily.
The most common form of sodium is table salt or sodium chloride.
However, when taken in excess, sodium leads to health problems. According to the Health Ministry, salt is the major source of sodium in the local diet.
The daily salt intake for Malaysians is 2,575mg, 25 per cent higher than the recommended amount.
According to the Consumers Association of Penang, sodium is often used as food additives. It may be present as monosodium glutamate (MSG, flavour enhancer), sodium bicarbonate (leavening agent), sodium nitrate and sodium benzoate (preservatives) and in many other commonly used sodium-based additives.
Excessive sodium intake has detrimental effects on health. Here are some examples:
HYPERTENSION
According to WHO, salt is by far the biggest source of sodium in today's diet. It has long been known to increase blood pressure. Several studies have found that excessive salt intake is a major cause of hypertension.
A high amount of salt causes water retention in the blood vessels which leads to an increase in blood volume and blood pressure. Reducing sodium intake can lower blood pressure by as much as 25 per cent.
A study of 4,000 Japanese people, published in the Journal Of The American Heart Association, confirms that high-sodium diets and those that gradually increase in sodium content, put people at a higher risk of developing high blood pressure.
HEART DISEASE
According to the Harvard School Of Public Health, a higher intake of salt can cause a 23 per cent increase in the incidence of stroke and a 14 per cent increase in heart disease.
A diet high in salty food will damage the walls of arteries and force them to become narrow. The heart then becomes weaker and will cause symptoms such as chest pain, breathlessness and chronic fatigue. Sudden cardiac arrest and heart failure can also happen.
OSTEOPOROSIS
Excessive sodium inhibits the body's ability to absorb and utilise calcium, leading to loss of bone mass and increased porosity, or osteoporosis. A high-salt diet can also drastically increase chances of fractures and other skeletal deformations.
A study of post-menopausal women over two years showed that loss of hip bone density was related to the 24-hour urinary sodium excretion. However, studies also showed that it was table salt that caused calcium loss and weak bones.
KIDNEY FAILURE
According to UK-based charity website Blood Pressure UK, a diet high in sodium will hamper the ability of kidneys to remove unwanted fluids in the body.
When you eat too much salt, the amount of sodium in your bloodstream increases, disrupting the balance and reducing the ability of the kidneys to remove water in your blood.
This causes extra strain on the blood vessels in kidneys and, over time, can damage them.
Evidence shows that people who eat salty foods regularly are more likely to develop kidney stones. Elevated blood pressure and blood volume are also extremely damaging to kidneys.
STOMACH CANCER
On its website, the World Action On Salt And Health (Wash) states that it has been known for many years that there is a relationship between chronic high salt intake and increased risk of gastric cancer.
It says studies have shown that a chronic Helicobacter pylori infection is closely associated with salt intake.
Helicobacter pylori is a major risk factor for stomach cancer, as it can lead to inflammation and gastric ulcers which can progress into stomach cancer. Salt has been found to increase the action of the bacteria.
Salt may also act as an irritant or inflammatory agent on the stomach lining, exposing it to carcinogens.
OBESITY
While salt is not a direct cause of obesity, Wash notes that eating salty food makes you thirsty, so you drink more fluids.
A study which analysed the sales of salt and carbonated beverages in the US between 1985 and 2005, showed a close link between the two, as well as a parallel link with obesity.
An analysis of UK National Diet and Nutrition Survey showed that salt intake was associated with both fluid intake and sugar-sweetened soft drink consumption.
This means salt intake has an effect on total fluid and sugary soft drink consumption, especially in children. Therefore, reducing salt intake can be important in reversing the current trend of childhood obesity.
WATER RETENTION
Sodium-rich foods cause water retention in the circulatory system, body tissues or cavities in the body. It results in temporary weight gain.
When you eat foods high in sodium, it causes a disturbance in the normal balance of sodium and potassium, which affects the kidney's ability to filter excess water from the bloodstream.
As a result, your body retains water that it will have otherwise expelled as urine. An extra 400mg of sodium can lead to an extra 1kg in water weight.
HYPERNATREMIA
Hypernatremia is an electrolyte imbalance indicated by a high level of sodium in blood. According to health and fitness website Fitday.com, hypernatremia occurs when a person is dehydrated and the kidneys cannot cope with the excess salt in the bloodstream.
It can happen when you vomit, have a fever or consume too much sodium from salty sports drinks or tablets as well as salty food.
This is a serious condition as it can lead to brain damage. Some of the symptoms include irritability, muscle cramps, confusion, depression and vomiting. Those with such symptoms will need medical attention.