Relaxing salt regulations in the UK has been linked to thousands of cases of heart disease and stomach cancer that would never have otherwise occurred, research suggests.
A study looked at salt intake in England before and after changes to legislation were introduced in 2011.
The 'tragic' Public Health Responsibility Deal saw the food industry set its own salt targets, rather than being monitored by an independent body.
Researchers blame this for an additional 9,900 cases of cardiovascular disease and 1,500 stomach cancer diagnoses in 2011-to-2017.
Adults are advised to consume no more than one teaspoon (6g) of salt a day, while children should have half this.
However, two thirds of us are thought to eat 8g of salt due when we overindulge in ready meals, processed meats and bread.
Salt raises blood pressure, which puts a strain on the heart. It may also damage the stomach lining and cause lesions that become cancerous.
Relaxing salt regulations in ready meals 'caused 9,9000 cases of heart disease' (stock)
The research was carried out by Imperial College London (ICL) and the University of Liverpool. It was led by Dr Anthony Laverty, lecturer in the school of public health at ICL.
Study author Dr Martin O'Flaherty, professor of epidemiology at the University of Liverpool, said: 'We are eating too much salt.
'Previous research has shown three-quarters of salt in our diet is hidden in processed food such as bread, ready meals and soups.'
Before the changes were introduced in 2011, salt intake was steadily falling every year by 0.2g for men and 0.12g a day for women.
When the regulations were relaxed, this slowed to a decline of 0.11g a day for men and 0.07g for women.
Between 2003 and 2010, the Food Standards Agency (FSA) closely monitored salt content and agreed on targets to reduce consumption with the industry.
For example, the FSA requested food manufacturers reduce salt content by between 10 and 20 per cent.
At the same time, public health campaigns pressured the Government into stricter regulations.
However, in 2011 the FSA's role was replaced by the Public Health Responsibility Deal.
This allowed food manufacturers to choose whether to sign up to salt-reduction targets.
'Evidence from around the world is now showing that mandatory approaches are much more effective than self- regulation by industry in reducing the amount of salt and sugar in our diet,' Dr Laverty said.
The researchers analysed data from the National Diet and Nutrition Survey, as well as other 'salt studies' carried out between 2000 and 2013.
HOW TO UNDERSTAND NUTRITIONAL INFORMATION ON YOUR FOOD
The vast majority of packaged foods in the UK come with nutritional information printed on the label.
The main things to look for are fat, saturated fat, salt (which may be called sodium), fibre and sugar – which is often listed as 'of which sugars' beneath carbohydrates.
Generally speaking, foods with higher fibre and lower saturated fat, salt and sugar are healthier.
Some supermarkets also label nutritional value with a traffic light system, in which more green points to healthier food.
The NHS advice on what is high or low is as follows:
High: more than 17.5g of fat per 100g
Low: 3g of fat or less per 100g
An adult's recommended daily allowance (RDA) of fat is around 70g.
High: more than 5g of saturated fat per 100g
Low: 1.5g of saturated fat or less per 100g
An adult's RDA of saturated fat is around 20g.
Sugars (aka of which sugars)
High: more than 22.5g of total sugars per 100g
Low: 5g of total sugars or less per 100g
An adult's RDA of sugars is around 90g.
Salt (aka sodium)
High: more than 1.5g of salt per 100g (or 0.6g sodium)
Low: 0.3g of salt or less per 100g (or 0.1g sodium)
An adult's RDA of salt is 6g or less.
Source: NHS Choices
These included urine analyses of more than 3,000 people, which suggested how much salt was in their daily diets.
The researchers then extrapolated their findings to the general population.
As well as affecting the nation's health, salt intake also set the UK economy back around £160million ($198m) between 2011 and 2017.
This included the cost of treating patients and a loss of productivity due to time off work.
Without action, the researchers predict the situation could become even worse.
Using a computer model, they estimated an additional 26,000 cases of cardiovascular disease and 3,800 incidents of stomach cancer will come about between 2019 and 2025.
This could cost an extra £960million ($1.1bn) to the UK economy over these six years.
'The FSA approach was one of the most robust strategies internationally,' Dr O'Flaherty said.
'Our research shows we now need an equally robust mandatory programme to accelerate salt intake reduction.
'This will require clear targets and penalties to ensure the food industry reduce salt content in foods.
'Softer, voluntary measures could generate additional heart attacks, strokes and cancer cases.'
Dr Graham MacGregor, professor of cardiovascular medicine at Queen Mary University of London, said: 'We've long known the Public Health Responsibility Deal was a tragedy for public health.
'This research markedly brings home the effect the deal had on the UK's once world-leading salt reduction programme.
'The slowing in the reduction of salt intake led to many thousands of entirely preventable occurrences of cardiovascular disease and stomach cancer, particularly in those from more deprived backgrounds'.
However, the researchers and other experts alike were quick to point out the study's shortcomings.
These included the relatively small number of participants, not measuring salt intake in the same people and expecting consumption to decrease year-on-year.
Dr Tom Sanders, professor emeritus of nutrition and dietetics at King's College London, also argued high blood pressure develops over 'many decades' and strokes generally occur in people over 70.
Reducing salt intake in the short-term may therefore not have lasting effects.
'The relationship between salt intake and stomach cancer is also doubtful,' he said.
'Infection with Helicobacter pylori and other causes of gastritis including excess alcohol intake and oesophageal reflux of acid, which is related to obesity, are probably far more important.'
Health Secretary Matt Hancock has pledged to introduce tougher salt targets.
Graham MacGregor, chairman for Action on Salt, said: 'It is up to the health minister, Public Health England and the Government to set up a coherent strategy where the food industry is instructed what to do.
'The UK has no active salt-reduction strategy, which is appalling. The last set of salt reduction targets expired at the end of 2017.
'It goes without saying, we now need to get our salt reduction strategy back on track for the benefit of public health, our overburdened NHS and the economy.'
However, Dr Sanders added: 'One reason why salt reduction has hit the buffers is many consumers find unsalted food unpalatable and salt also has a role in food preservation.
'Further reductions in the level of salt in processed food may be better achieved by encouraging the partial replacement with potassium chloride for salt rather than heavy-handed legislation.'