Walkers Crisps are to put real meat in their chicken and smoky bacon crisps, upsetting vegetarians and many religious fans of the Leicester-made snacks.
The new Home Grown recipes of Walkers Crisps, which include real pork and chicken from British farms in two of the 10 revised flavours, have angered people who have enjoyed eating meat-flavoured crisps guilt-free.
Caroline van Dijk, a vegetarian who owns the Good Earth restaurant, in Leicester city centre, said she did not understand the move, which is causing a storm on Twitter.
She said: "I like the smoky bacon crisps and I know other vegetarians who do, too.
"Why do they have to meddle?
"I think a lot of people will be angry and Walkers will need to change the packets because people will just presume there's no meat still."
Suleman Nagdi, spokesman for the Leicestershire Federation of Muslim Organisations, said the company now had a moral duty to make sure the packets contained clear warnings.
He said: "Pork is forbidden for Jews and Muslims and most chicken produced is not halal.
"People have always known the flavours in Walkers crisps are artificial and it will be important for Walkers to make it clear what is happening, especially after the horse meat news.
"Walkers are going to see a drop in sales among Britain's Muslim community."
Other flavours changing ingredients include prawn cocktail crisps, which will have real tomato in them.
Sour cream and chive crisps will include sour cream from Dorset and cheese and bacon flavour will include cheddar from Somerset.
Some of the other meat flavours may also have their recipes changed to include real meat products in the future.
The company insists it is sticking to its plan to launch the flavours today, despite the backlash.
A company spokeswoman said: "Home Grown will replace the crisps in the classic range and it's a permanent move.
"It's not to restrict anyone but Walkers wanted to move to working with tastier ingredients.
"It may be rolled out across the whole range."
To promote the crisps, Gary Lineker joined his dad on a trip around the country, including a visit to the Lineker's stall on Leicester Market where Barry sold fruit and veg for 40 years.
During their trip around the country, Gary and Barry tasted tomatoes from Walkers' growers in Evesham, visited a Walkers' potato farmer in Hampshire and sampled cheddar cheese from a Walkers' cheese producer in Somerset.
Gary said: "Everyone knows I love my Walkers crisps but to fully appreciate and understand this journey of taste and provenance, I needed a hand from someone who knew his fruit from his veg, so my Dad was the perfect partner."