The government's maximum daily salt intake target has been set too high for people to avoid unnecessary stroke and heart deaths, UK experts are warning.
Consensus Action on Salt and Health (Cash) says the 6g figure was picked as an achievable food industry target.
The World Health Organization's 5g target could save four million lives a year worldwide, BMJ online suggests.
Cash wants a 4g target, but the Food Standards Agency backs its 6g target. A UK adult averages 8.6g of salt daily.
Although this is an improvement on past years, it is still well short of the both the World Health Organization (WHO) and the UK target.
Too much salt is known to raise blood pressure, which increases the risk of heart disease and stroke.
Now European researchers have shown that people who regularly consume 10g of salt a day increase their stroke risk by nearly a quarter and their heart disease risk by about a fifth.
Given that stroke ends in death for one in three, and that heart disease kills one in five who have it, sticking to recommended salt intakes has the potential to save millions of lives, say the UK and Italian researchers.
Based on their results, they estimate that keeping daily salt intake to a maximum of 5g at the current population level could avert 1.25 million deaths from stroke and almost three million deaths from cardiovascular disease each year.
And this is probably an underestimate, they say, because measures of salt intake are imprecise.
Professor Francesco Cappuccio and his team reviewed 13 studies involving more than 170,000 people between 1996 and 2008.
Joanne Murphy, of the Stroke Association, called for consistent labelling on food packaging so consumers could be more aware of how much salt already exists in the food they buy.
Consensus Action on Salt and Health (Cash) says the vast bulk of the salt we consume is down to levels in the food we buy, which is set by manufacturers.
Chairman of Cash, Professor Graham MacGregor, said: "All the evidence now points that the target should be set lower. Getting it below 6g would give more benefit."
He said the 6g figure, set by the government's expert advisers back in 1994, had been "plucked out of the air" because the evidence at the time was not that good.
"We knew it was important to cut salt intake and we wanted a target that the food industry would accept.
"But now it's clear that the UK target should be lowered."
He said a target of 4g or lower would be sensible and achievable.
He said the food industry had done well cutting salt levels but said it needed to keep the effort going.
An FSA spokesperson said: "We base our recommendations on the most up to date and independent science.
"Achieving the 6g intake target will prevent a further 17,500 premature deaths every year and save the economy around £4bn."