Twenty-seven years after the ill-fated launch of New Coke, the threat of having a cancer warning placed on its famous red bottles is forcing Coca-Cola to revise the closely guarded ingredients again.
With its arch rival Pepsi, Coca-Cola is altering its drink in the US after the state of California declared one of its flavourings a carcinogen though it will continue to sell the old form of the drink in Britain and the rest of Europe, with no cautionary labelling.
The two drinks have been made to include less of 4-methylimidazole, a caramel flavouring known as 4-MEI, which the National Institute of Environmental Health Sciences in the US has linked it to cancer in mice and leukaemia in rats. Under Californian law, drinks containing a certain level of carcinogens must have a cancer-warning label on their packaging.
But the two companies - which, combined, make up 90 per cent of the soft-drink market in the US - insist the ingredient is not a health risk.
Coca-Cola said yesterday the cancer warning is: "scientifically unfounded".
The American Beverage Association also said there is no evidence that the ingredient poses a risk to humans. And the US Food and Drug Administration said someone would have to drink 1000 cans of Pepsi or Coke per day to ingest the same dosage of the chemical given to the laboratory mice.