Children in the UK are eating far too much salt, with much of it coming from breads and cereals, research suggests.
Children should eat less than a teaspoon of salt a day, but 70 percent of the 340 children in the study published in Hypertension ate more than this.
Breads and cereals accounted for more than one-third of the salt in children's diets.
A fifth came from meat and one-tenth from dairy products.
This was despite a UK-wide drive to cut salt levels in food.
The Department of Health said its voluntary salt reduction code with manufacturers was working, but agreed that more progress is still needed.
Manufacturers say they are reducing salt in many products, including bread.
The study authors say efforts must be redoubled because salt increases the risk of high blood pressure from a very young age, and high blood pressure can lead to heart disease and stroke.
For the research, they asked the parents of the 340 children to keep a detailed food diary and take photos of all foods and beverages their child consumed, as well as any leftovers.
At the same time, the investigators analysed urine samples from the children to get an objective measure of salt intake.
On average, five and six-year-old children in the study consumed 3.75g of salt a day - more than the recommended 3g maximum.
Eight and nine-year olds consumed 4.72g a day - within their 5g limit.
Thirteen to 17-year-olds consumed 7.55g a day - more than the 6g limit.
Boys tended to have higher salt intake than girls, particularly in the older and younger groups - about 1g higher per day in 5 to 6-year-olds, and 2.5g per day higher in 13 to 17-year-olds.
Much of the salt consumed was from processed foods rather than added at the table.
Lead researcher Prof Graham MacGregor, who is chairman of both the charity Blood Pressure UK and the lobby group Consensus Action on Salt & Health (CASH), said: "It is very difficult for parents to reduce children's salt intake unless they avoid packaged and restaurant foods and prepare each meal from scratch using fresh, natural ingredients."
He said manufacturers needed to do more to cut out salt.
Each 1g reduction in salt consumption would save thousands of lives from heart disease and strokes, he said.
A Department of Health spokeswoman said: "On average, we are eating approximately 2g of salt more each day than the recommended amount and it is vital that we address this. This is why we are working with industry through the Responsibility Deal to reduce the amount of salt in foods. We have just finalised new salt targets for 76 categories of food and call on industry to sign up."
Salt levels in many of our foods have reduced significantly, some by 40 percent-50 percent or more, and since 2007 more than 11 million kg of salt have been removed from the foods covered by the salt reduction targets. However, average salt consumption remains high at around 8.1g per day, so there is still a long way to go to meet the 6g per day population intake goal.
Manufacturers insist they are reducing salt in many products, including bread.
Terry Jones of the Food and Drink Federation said: "Although salt intakes in the UK have reduced significantly in recent years, we recognise that more work must be done to help and encourage people to stay within recommended limits. This is why food manufacturers have a long history of reducing salt in products and providing clear on-pack labelling to help people know what a product contains."
Luciana Berger MP, Labour's shadow public health minister, said the government had lost its way on public health.
She said: "We are consulting parents and experts about what's in children's food and whether they would find it helpful to have maximum levels of sugar, fat and salt."
The daily recommended maximum amount of salt children should eat depends on age:
One to three years - 2g salt a day (0.8g sodium)
Four to six years - 3g salt a day (1.2g sodium)
Seven to 10 years - 5g salt a day (2g sodium)
11 years and over - 6g salt a day (2.4g sodium)