Any food packaged by McDonald's tastes better to most preschoolers, says a study that powerfully demonstrates how advertising can trick the taste buds of young children.

'You see a McDonald's label and kids start salivating.'—Diane Levin, childhood development specialist

Even carrots, milk and apple juice tasted better to kids if it was wrapped in the familiar packaging of the Golden Arches. The study had youngsters sample identical McDonald's foods in name-brand or unmarked wrappers. The unmarked foods always lost the taste test.

"You see a McDonald's label and kids start salivating," said Diane Levin, a childhood development specialist who campaigns against advertising to kids. She had no role in the research.

Study author Dr. Tom Robinson said the kids' perception of taste was "physically altered by the branding." The Stanford University researcher said it was remarkable how children so young were already so influenced by advertising.

The study involved 63 low-income children aged three to five from Head Start centres in San Mateo County, Calif. Robinson believes the results would be similar for children from wealthier families. The research, appearing in August's Archives of Pediatrics & Adolescent Medicine, was funded by Stanford and the Robert Wood Johnson Foundation.

McDonald's to limit advertising to children

The study will likely stir more debate over the movement to restrict ads to kids. It comes less than a month after 11 major food and drink companies, including McDonald's, announced new restrictions on marketing to children under 12.

McDonald's says the only Happy Meals it will promote to young children will contain fruit and have fewer calories and less fat.

"This is an important subject and McDonald's has been actively addressing it for quite some time," said company spokesman Walt Riker. "We've always wanted to be part of the solution and we are providing solutions."

But Dr. Victor Strasburger, an author of an American Academy of Pediatrics policy urging limits on marketing to children, said the study shows too little is being done.

"Advertisers have tried to do exactly what this study is talking about — to brand younger and younger children, to instil in them a … desire for a particular brand-name product," he said.

Children said milk, carrots packaged with logo tasted best

Just two of the 63 children studied said they'd never eaten at McDonald's, and about one-third ate there at least weekly. Most recognized the McDonald's logo, but it was mentioned to those who didn't.

The study included three McDonald's menu items — hamburgers, chicken nuggets and french fries — and store-bought milk or juice and carrots. Children got two identical samples of each food on a tray, one in McDonald's wrappers or cups and the other in plain, unmarked packaging. The kids were asked if they tasted the same or if one was better. (Some children didn't taste all the foods.)

McDonald's-labelled samples were the clear favourites. French fries were the biggest winner; almost 77 per cent said the labelled fries tasted best while only 13 per cent preferred the others.

Fifty-four per cent preferred McDonald's-wrapped carrots versus 23 per cent who liked the plain-wrapped sample. The only results not statistically clear-cut involved the hamburgers, with 29 kids choosing McDonald's-wrapped burgers and 22 choosing the unmarked ones.

Less than 25 per cent of the children said both samples of all foods tasted the same.