One in four people mistakenly believe expensive rock and sea salts are healthier than table salt, according to a study published today.
The report found that the sodium chloride content of gourmet salt products is nearly 100%, and is just as damaging to health as regular salt despite claims that they are "natural" and "contain minerals".
Professor Graham MacGregor, chairman of Consensus Action on Salt and Health, which carried out the chemical research, criticised television chefs for promoting the liberal use of salt during cooking.
"It is disgraceful that chefs still encourage people to use so much sea and rock salt," he said.
"This has the added danger that, as the crystal sizes are much larger and don't taste as salty, more salt is consumed."
A survey of Which? members who buy rock and sea salts revealed they do so because they believe it is healthier (24%) or more natural (39%) than table salt.
Which? chief policy adviser, Sue Davies, said: "Many of us are trying to reduce the amount of salt in our diet, but our research shows that people are needlessly spending more money on premium salt as they often believe it's healthier than traditional table salt.
"Given that most of the salt we eat is already in the food we buy, the cheapest and healthiest option would be to stop adding extra salt to food altogether.
"Which? is calling on food manufacturers to reduce the amount of salt in their foods, and we'll be monitoring their progress over the coming months."