Restaurant groups including McDonald's, Nando's, Pizza Express and Wagamama have all been criticised for serving salads containing high levels of salt.
The criticism comes after Consensus Action on Salt & Health (CASH) conducted a survey of 650 ready-to-eat salads from restaurants, cafés, fast-food restaurants and supermarkets.
It said it found that three quarters (77% of 511 products) contained more salt than a packet of crisps (0.5g per portion).
The findings came despite the fact that there were calls in 2010 to lower salt in salads, the group said.
When it came to out of home salads, CASH said it discovered that:
• A McDonald's ‘crispy chicken & bacon salad' had more salt (1.3g vs 1.2g), fat (19g vs 8g) and calories (380kcal vs 250kcal) per portion than a McDonald's hamburger.
• The PizzaExpress ‘grand chicken Caesar salad' contained 5.3g of salt per serving (the equivalent of two and a half Big Macs)
•Wagamama's 'lobster super salad' contained 4.5g of salt per serving - three quarters (75%) of the maximum recommended maximum daily intake for an adult.
•Nando's 'Mediterranean salad with chicken breast' contained 4g of salt per serving - two thirds (67%) of the maximum recommended intake.
And it added that even specially created foods for health-conscious consumers could also contain a high salt content. It singled out:
•Pod's 'chicken detox box', which contained 4g of salt per serving.
•PizzaExpress' 'Leggera salmon salad', which is under 500 calories but contains 2.4g of salt per serving.
Graham MacGregor, CASH chairman and professor of cardiovascular medicine at the Wolfson Institute, Queen Mary University of London said: "It is nonsensical that something as seemingly healthy as a salad should contain an ingredient that is proven to be harmful to your health. While we congratulate the responsible manufacturers that have gradually reduced the salt in their products, we urge all manufacturers to sign up to the Department of Health's 2017 salt pledge and to cut the salt in their dishes now. Many salads are deceptively high in salt, and the very large variation of salt content shows that the highest ones can easily be reduced. The food industry needs to show much greater responsibility for its customers' health."
However, several restaurant operators defended the level of salt in their salads, claiming that they made nutritional information clear to customers and offered them a choice of a range of options.
A spokesperson for PizzaExpress said: "We offer low salt salad options which start at 0.3g of salt per serving. Our full nutritionals, including salt levels, are available to everyone so it's no secret that, of the eight salads currently on our menu, two are higher in salt.
"The salads highlighted in the report contain ingredients that are naturally higher in salt, such as the anchovies and cheese in our grand chicken Caesar and the goat's cheese in the warm vegetable & goat's cheese salad. They are also both served with dough sticks which, again, unavoidably contain salt. We do not cook with salt in our restaurants and do not put salt on our tables because we do not believe in adding unnecessary salt to our menu. We are also always happy to adapt dishes so they contain more, less or none of any ingredient, allowing us to meet the needs of our guests. As part of the Responsibility Deal, we're committed to a programme of salt reduction and will continue to communicate openly with our guests - something CASH has praised us for."
Meanwhile, a spokesperson for McDonald's said: "When looking closely at the findings it highlights that our salad contains far less salt than similar products from other companies. When being compared in this way, our salad offering contains the least amount of salt.
"We work continuously to evolve our menu by adding more choice and adapting our recipes to remove salt, fat and sugar without changing the McDonald's taste our customers love. We provide clear nutrition information about our food in a number of ways including our menu boards, trayliners, mobile app and website so that our customers can make informed choices that are right for them. Since 2007 our salads have been part of this process and the crispy chicken and bacon salad now contains 60% less saturated fat and 19% less salt as a result. Customers who are worried about salt levels in food have the option to choose from a crispy chicken salad option, removing the bacon which is naturally salty or to try our grilled chicken salad option."
Tim Hall, founder of Pod, said: "Salt is vital for good health, especially in hot weather when the body loses lots of sodium. The salt in the chicken detox box comes naturally from the ingredients, such as soya dressing and nori - we never add any salt to our recipes ever and we have no salt in our kitchens. This dish is also designed for the calorie conscious, who are less likely to be eating large quantities of other foods throughout the day. It's well within government guidelines and we have lots of other salads and dishes that contain almost no salt at all."
No-one from Nando's or Wagamama was available to comment.
CASH also pointed to some operators offering low salt salad options. It singled out Caffè Nero among the restaurant brands that offers a low salt salad with its "chicken salad with a Caesar dressing", which has just 0.5g of salt in a 178g serving.