The supermarket chain, which has made a name for itself by challenging established practice, said "almost all" its own-label products would be affected by the reduction of up to 25 per cent in their salt content.
However, more than half the foods sold at Asda are branded products, which will be unaffected by the move.
The Food and Drink Federation, which represents food manufacturers, dismissed the move. Michael Mackenzie, its director general, said: "This is nothing new. Food manufacturers have been producing low-sodium product ranges for years."
Asda claimed it was the first to make an across-the-board cut on this scale. It was backed by Professor Graham Macgregor, head of the blood pressure unit at St George's hospital, Tooting, south London, and a campaigner on the evils of salt.
Professor Macgregor has accused manufacturers of preparing foods containing as much salt as found in seawater. He claims they have resisted pressure to reduce salt levels because it is a cheap flavour enhancer and consumers have got used to the taste.
"This is a very important initiative that will act as a signal to other food suppliers. The way to reduce salt intake is a gradual and sustained reduction in the salt content of all processed food. It can be achieved without the public even being aware of it."
Asda may have been encouraged by the experience at Heinz, which has a policy of reducing the salt and sugar in all its products. Since 1989 it has cut the amount of salt in a tin of baked beans by 14 per cent with no drop in sales.
Sainsbury's claimed yesterday that it had stolen a march on Asda. A spokeswoman said: "We have been reducing the salt, fat and sugar content of our products since 1994. So far we have reduced the salt content by at least 25 per cent in 2,800 products."
Medical experts say high salt consumption is a big cause of high blood pressure, which increases the risk of heart attack and stroke.
Last year, the Committee on Medical aspects of Food Policy (a government advisory body) said a one-third reduction in salt consumption could save 34,000 lives a year. This would mean reducing average daily consumption from nine grams to six.
A reduction on this scale cannot be achieved by cutting the amount of salt sprinkled on food or added in cooking since processed foods account for more than 70 per cent of the salt content of the average diet.
However, the damaging effects of salt have been a matter of scientific dispute. A report in the journal Science earlier this year suggested that high blood pressure was linked with a mineral-deficient diet rather than excess salt, caused by a switch from fruit, vegetables and milk to processed foods and soft drinks.
A study published in The Lancet last March found death rates were lowest in people with the highest salt intake. The US study of 11,000 people asked them to record all they had eaten in the previous 24 hours, and then followed them up over the next 20 years. Those with the highest salt intake had an 18 per cent lower death rate.
However, Professor Macgregor said the study was flawed. The practice of assessing salt intake on the basis of a "single dietary recall" was notoriously inaccurate, he said.
n The average Briton eats nine grams of salt a day.
n Some salt is necessary, but nutritionists estimate people can get by on just one gram a day.
n A high-salt diet is believed to cause high blood pressure, leading to heart attacks and strokes, and may aggravate asthma, osteoporosis and kidney disease.
n About 70 per cent of salt in the diet is pre-added to ready-made meals and processed foods.
n One beanburger can contain about six grams.
n Salt is added to enhance flavour. It also allows more water to be added to food, increasing its weight at no extra cost to producers.
n A tin of baked beans contains two grams, a bowl of bran 0.5 grams.
n Many processed foods are labelled with the sodium content to disguise the amount of salt (sodium chloride) present. To get the level of salt the sodium content should be multiplied by 2.5.
n Salt is the oldest preservative and condiment known to man.
n Medical experts recommend the daily intake of salt be reduced to six grams.Reuse content