Leon may be forced to rename its Original Superfood Salad after the Advertising Standards Agency (ASA) upheld a complaint about the nutrition and health claims associated with the dish.
The chain has been using the term to describe its basic salad recipe since the first restaurant opened on London's Carnaby Street in 2004.
The Original Superfood Salad, which Leon claims on its website was "invented by Leon and the inspiration for others", includes broccoli, peas, cucumber, avocado, quinoa, feta, fresh mint, parsley, toasted seeds and a pot of vinaigrette.
Leon argued that the term ‘superfoods' was a general health claim that it had been using "exclusively in the context of a brand name for a range of salads which they had sold since 2004".
It added that the term was in use as a brand name before the regulations on nutrition and health claims made on food were implemented in 2005.
But the ASA upheld the complaint. It said: "The ASA considered the reference to ‘superfoods' was likely to be understood as relating to the general benefits of the product or its ingredients for overall good health or health-related wellbeing. As such, we considered the claim ‘Original Superfoods Salad' was a general health claim."
It acknowledged that Leon presented evidence that showed that it had used variants of the name ‘Superfood Salad' since summer 2004 and that ingredients had varied, but that it "was not sufficient to establish the requisite goodwill".
As a result the ASA said that the claim must not appear again in its current form.
The judgement said: "We told Leon Restaurants Ltd not to make references to general benefits of food for overall good health or health-related wellbeing in brand names unless those claims were accompanied by a permitted health or nutrition claim."
In a statement Leon said: "We created the original Superfood Salad in 2004, and it has since inspired many others. It would be a shame if the Leon Superfood Salad had to change its name. We respect the ASA process, and will be taking the next step of applying for an independent review."