Salt is made up of sodium and chloride and is added to foods for different reasons. It is used as a preservative; influences the flavour of foods; improves the texture and has other important functions such as controlling yeast fermentation in breadmaking. In fact, salt curing is one of the earliest known forms of food preservation for meat and fish.

Sodium is an essential mineral required by the body. One of its functions is to help balance the levels of fluid in the body, which helps to maintain normal blood pressure and keep nerves and muscles working properly. Excessive intake of sodium may cause problems in some individuals. Sodium is the dietary element at the centre of the medical debate linking sodium intake with high blood pressure (hypertension). However, when exercising strenuously, particularly in hot weather, it is important to replace the salt and fluid lost through perspiration.

Salt (or table salt) is not the only source of sodium in our diet. About 10% of the sodium we eat is naturally present in foods such as milk, eggs and spinach. Around 15% is added during cooking or at the table and the rest comes from many different processed foods such as bread, breakfast cereals, meat products, soups, sauces, ready-meals, pre-packed sandwiches, soya sauce, stock cubes, cheese, pickled products and cured fish.

Sodium is also found in additives such as baking soda (sodium bicarbonate) and sodium saccharin (sweetener). Other examples include sodium acetate (flavouring), monosodium glutamate (MSG), sodium ascorbate (antioxidant) and sodium nitrite (preservative).