Coca-Cola and Pepsi are changing the way they make their drinks to avoid having to label their products with a cancer warning to comply with California law.
The new recipe for the caramel colouring used in cola contains less 4-methylimidazole - a chemical that California has added to its list of carcinogens.
The changes have already been implemented in California and will soon be expanded nationally.
"While we believe that there is no public health risk that justifies any such change, we did ask our caramel suppliers to take this step so that our products would not be subject to the requirement of a scientifically unfounded warning," Coca-Cola representative Diana Garza-Ciarlante told Associated Press.
"Consumers will notice no difference in our products and have no reason at all for any health concerns," the American Beverage Association said.
The 4-methylimidazole chemical has been linked to cancer in mice and rats, according to one study, but there is no evidence it poses a health risk to humans.
The US Food and Drug Administration claims a person would need to drink 1,000 cans of Coke or Pepsi to take in the same dose of the chemical that was given to the lab rats.
Coca-Cola and Pepsi account for almost 90% of the soda market, according to industry tracker Beverage Digest.
Coca-Cola have issued a statement assuring people the taste will not change and it is the formula that is changing, not the recipe.
A spokesperson for the company said: "The caramel colour in all of our products has been, is and always will be safe, and The Coca-Cola Company is not changing the world-famous formula for our Coca-Cola beverages. Over the years, we have updated our manufacturing processes from time to time, but never altered our Secret Formula.
"We have asked our caramel manufacturers to modify their production process to reduce the amount of 4-MEI in the caramel, but that will have no effect on the formula or on the great-tasting, high-quality products that consumers expect from us. These modifications will not affect the colour or taste of Coca-Cola."