Many strokes and heart attacks are occurring because of delaying tactics by some food companies

Professor Graham MacGregor

Sodium is one of salt's major constituents and has been linked to high blood pressure, strokes and heart attacks.

Although some industry advisors question just how great an impact salt actually has on health, campaigners want consumers to be aware of how much they eat unwittingly.

Of the UK's total salt consumption, only a small proportion is added to people's diet at the table or in cooking.

Eighty five per cent - 220,000 tonnes a year - is put into food during the industrial processing of products such as bread, some cereals and ready meals.

Salt Awareness Day

Tuesday is National Salt Awareness Day and the charities and medical specialists who organise it say it is vital consumers are aware of the hidden salt they eat.

The campaigners estimate people in the UK eat 20 times more salt than they actually need to live.

They recommend cutting each person's daily intake to six grammes - about a level teaspoonful.

People in the UK consume enough salt to fill St Paul's Cathedral

Professor Graham MacGregor, of the Action On Salt campaign, says recent studies have confirmed that cutting salt intake will cause an immediate and important fall in blood pressure.

A three gramme reduction in intake has been predicted to reduce strokes in the UK by a quarter and heart attacks by16%.

Prof MacGregor said: "The food industry must now reduce the quite unnecessarily high concentration of salt in processed foods.

"It's often equivalent to, or approaching that of seawater.

"Tragically, many strokes and heart attacks are occurring because of delaying tactics by some food companies."

Saltless loaf

But food industry representatives say salt is used not just to help taste, but as a preservative - important for food safety - and to improve texture.

The director general of the Food and Drink Federation, Sylvia Jay, says, "We all need some salt in our diets.

"However, there has been a great deal of controversy over salt - with scientists trying to establish what amount people should eat.

"Clearly, as with all things, moderation is the key. Manufacturers do not hide salt in their products. Any added salt is always shown on the ingredient list."

Some supermarket chains and companies have responded to consumer demand and already cut down on salt in their brands.

In fact, last year more than 1,000 tonnes were removed from the diet.

Bread, for example, is 25% less salty than it was in the early 1980s.

But medical specialists are urging all food manufacturers to make gradual and sustained reductions.