The burger chain is portraying its Whopper covered in mould in print and TV ads running in Europe and the US.
The company, already known for irreverent ad campaigns, turned it up a notch, including a time-lapse of a decaying burger on Twitter.
The restaurant, based in Miami, Florida, says it has removed artificial preservatives from the Whopper in several European countries - including France, Sweden and Spain - and about 400 of its 7346 US restaurants.
By the end of this year, Burger King said all food items - including sandwiches, sides and desserts - will be free from artificial colours, artificial flavours and artificial preservatives in the US and select European countries, including Germany and the United Kingdom.
McDonald's announced in 2018 that it was removing artificial colours, flavours and preservatives from seven of its burgers.