Most British adults do not know what the recommended maximum daily salt intake is, according to a poll for the British Heart Foundation (BHF).

Only 19% of those surveyed stated the 6g per day maximum recommended by the Government, which is about a teaspoon of salt, while 65% were not confident in estimating their daily salt intake.

The findings from a YouGov survey of more than 2,000 British adults come as the Action on Salt (AoS) campaign group called on the Government to get tough on the food industry and enforce the salt targets, either by legislation, or a levy on foods that exceed the targets.

AoS said that out of 1,387 pizzas it surveyed, takeaway pizzas contained more than double the amount of salt than those bought in supermarkets.

Some 66% of pizzas sold in restaurants and takeaways contained 6g or more salt per pizza, according to the group.

The BHF believes that no time should be lost trying to cut levels of salt in everyday foods to make healthy eating easier for families.

Eating too much salt can lead to health problems including high blood pressure, which can be linked to half of all heart attacks and strokes in the UK, it adds.

In its survey the BHF also found that 86% of those questioned correctly stated the majority of salt consumed in the UK comes from shop-bought food, or is from food served outside of the home.

John Maingay, the BHF’s director of policy and influencing, said: “This research clearly shows that people don’t feel they know how much salt they are eating, and just providing people with that information isn’t going to help when there are high salt levels in so many of the foods we buy.

“There is a clear case for helping people eat more healthily by taking salt out of food before it is bought. We need Government action to drive all parts of the food industry to play their part and reduce the amount of salt they are serving to us.”

Both the BHF and AoS point towards the soft drinks industry levy, introduced a year ago, as a successful regulatory way to try to tackle the issue.

The average amount of sugar a UK household consumed via soft drinks dropped by 30g per week, and it has not affected sales of soft drinks, they said.

Sonia Pombo, registered nutritionist and AoS campaign lead, said: “We know it is possible to reduce salt in pizzas, as demonstrated by some responsible businesses, so there is no reason why others can’t also do so.”

Mhairi Brown, registered nutritionist and AoS policy lead, said: “The Government showed brilliant leadership when it launched the soft drinks industry levy, a tax on sugary drinks manufacturers that lowered the amount of sugar the nation was unknowingly drinking without raising prices.

“The Chancellor must now expand this successful levy to food companies who refuse to lower excessive salt levels in their food, to protect our health, our economy and our NHS.”

A Department of Health and Social Care spokesman said: “Thanks to our salt reduction programme, the amount of salt in food has fallen by around 20% – helping to prevent nearly 70,000 heart attacks and strokes while reducing pressure on the NHS.

“We’re also taking firm action by restricting the location of foods high in fat, salt, or sugar, which will bring health benefits of over £57 billion and save the NHS £4 billion.

“We will continue to work closely with industry to make it easier for people to make healthier choices.”