Read the labels to check exactly what you are buying, say advisers
People choosing wheat or dairy-free products could be risking their heart health because many are loaded with salt, a study reveals.
Consensus Action on Salt and Health surveyed 71 own-label "free from" products from five leading supermarkets in the UK.
Over half contained more salt than the retailer's standard version of the product. Some had six times as much.
Experts urged consumers to always check the labels.
Less than a third of the "free from" products studied had lower levels of salt than equivalent standard products.
Sainsbury's Free From Jaffa Cakes have 0.67g of salt per 100g, compared with 0.1g of salt per 100g in standard Sainsbury's Jaffa Cakes.
This is more than six times the salt level of the standard version.
Morrison's standard Chocolate Chip Cookies contain 0.5g of salt per 100g, while their Free From version contains 1.5g per 100g - three times as much.
ASDA Free From Double Chocolate Muffins have over three times as much salt as ASDA Double Chocolate Muffins, 1g per 100g as opposed to 0.3g per 100g.
Tesco's Free From Victoria Sponge has more than double the amount of salt as its standard cousin, 1.4g per 100g compared with 0.6g of salt per 100g.
All of the five supermarkets, which included Waitrose, did have some "Free From" foods that fared better than standard products on salt levels.
This, says CASH, shows that there is no technical reason why "free from" products have to have higher salt levels.
Graham MacGregor, chairman of CASH and professor of cardiovascular medicine said: "In general, it has been the supermarket own-label products that have led the way in salt reduction, but it seems that own-label products for people with existing health problems have not been a top priority for the retailers.
"They must now reformulate the higher-salt products immediately, so that people suffering from Coeliac disease or other related conditions do not have to put their health in further jeopardy."
He said people should aim to keep their salt consumption below the recommended maximum limit of 6g a day.
Too much salt in the diet raises the risk of heart disease.
A spokeswoman for the British Nutrition Foundation said: "The advice for people selecting 'free from' foods is the same as for other consumers buying any foods - check the labels. Be savvy about what you buy.
"There are different varieties available, with different ingredients."
Victoria Taylor, of the British Heart Foundation, said: "The high levels of salt found in these products is concerning as the products looked at include basic foods - like bread - that are eaten on a daily basis.
"Eating too much salt on a regular basis is linked to raised blood pressure, a risk factor for heart disease."
Mike Rich, of the Blood Pressure Association, said eating less salt was one of the easiest ways to reduce high blood pressure.
He said: "Many people buy 'free from' products to avoid having health problems, so it's very disappointing that so many have been found to be loaded with unnecessary salt."
In a statement, Sainsbury's said: "We take salt reduction very seriously, and are actively working on reducing the salt levels in our free from range.
"As of January 2010 all Sainsbury's 'free from' products will meet the FSA's 2010 or 2012 salt targets and will be nutritionally comparable to the equivalent products in our main ranges."