The Advertising Standards Authority (ASA) has ruled that the vegetarian meat-substitute Quorn has been misleading the public by calling itself a "mushroom protein".
Complaints were made about the term because, although Quorn is fungal in origin, it is not derived from mushrooms.
When Quorn was launched 17 years ago it used the term "mycoprotein" to describe its main ingredient.
But after a woman suffered an allergic reaction to the product it was agreed the public did not understand what "mycoprotein" meant. Marlow Foods, the maker of Quorn began using "mushroom protein" to describe its products because it said it was more helpful for consumers.
But now the ASA has ruled the term "mushroom protein" is misleading. It has told Marlow Foods to remove it from packaging or give, in the same size font, a description of the mycoprotein or fungal origin of the product.
A spokesman for Marlow Foods said: "We accept the ASA's ruling and are pleased that the authority recognised that we had used this wording "mushroom protein" in the interest of consumer safety.
"We have always strived to provide meaningful consumer information. We will take the ASA's comments into account when planning any future advertising."