The new packaging for its 30-strong portfolio, which will start hitting shelves in the next two weeks, will also feature GDAs alongside traffic lights and nutrient content per portion.
Until now, all brand manufacturers - led by the Food and Drink Federation - had been united in their opposition to the use of the Food Standards Agency's recommended traffic light system, which uses a 100g measure rather than portion sizes to allocate red, amber or green.
The main bone of contention is that the method creates an unfair measure for foods not intended to be eaten in such a quantity, such as cheese or cereal.
McCain UK managing director Nick Vermont said the decision had been made after the combination approach went down best in consumer research. "It was a eureka moment for us and consumers," he said. "We have the FSA on one side with traffic lights and the FDF on the other with GDAs. Why not have both? Consumers are not stupid; they want more information, not less, and the basis of our campaign is that we have nothing to hide."
Julian Hunt, director of communications for the FDF, refused to be drawn on whether the move was a blow for the anti-traffic light brigade. "There is clear agreement across industry that GDAs are the best way to provide consumers with useful information about their food. This consensus enables companies to develop consistent, complementary approaches to providing on-pack information."
He added: "The overwhelming majority of manufacturers do not believe adding traffic lights to their GDA schemes will help their consumers. But it is up to individual manufacturers how they implement GDAs on pack."
However, a spokeswoman for the FSA said it warmly welcomed the move. "It joins the four major retailers that have already adopted traffic light colour-coded schemes. It is encouraging to see they recognise the importance of helping people make healthier choices."
She added: "We know that the use of traffic light colour coding is key to helping people make informed decisions about their food and that this is the type of simple scheme people want to see on products. We hope other manufacturers will follow McCain's lead."
Vermont said that the labelling move was part of a wider campaign to change misconceptions about the company's chips.
"Customers think that products like chips are made in all sorts of weird and wonderful ways. We want to put the record straight."who's doing what
Combination approach: McCain Foods, Asda
Traffic lights: Sainsbury's, The Co-operative Group, Waitrose
GDAs: AG Barr, Britvic, Calypso, Coca-Cola, Danone, Gerber, Kellogg, Kraft, Morrisons, Nestlé, Nicols, PepsiCo, Shloer, Somerfield, Sunny D, Tesco, Unilever