Advertisements for junk food may be cluttering many of the Web sites most popular with children, a new study suggests.

When researchers examined 28 of the Web sites most frequented by children, they found that the majority of food products advertised there met experts' criteria for foods to avoid.

Ads for sugar-laden cereals, candy, soda or fast food populated a majority of the Web sites, which included sites one would not readily associate with food, like those run by Nickelodeon and the Cartoon Network, among others, noted Dr. Lori Dorfman, director of the Berkeley Media Studies Group in California and one of the researchers on the study.

In contrast, of the 77 advertised products across all the Web sites, only five were foods that children should be encouraged to consume, the researchers report in the American Journal of Public Health.

Cartoon Network declined to comment on the study, and calls to Nickelodeon were not immediately returned. But a spokesperson for PBS Kids -- cited for having fast food brands represented on its Web site -- said that its representation in the study is misleading.

PBS Kids does not accept advertising, and it does not market food products to children, said Lesli Rotenberg, senior vice-president of children's media.

Instead, the site carries, at the bottom of some pages, the logos of various PBS sponsors -- which include fast-food restaurants like McDonald's and Chick-fil-A. Children will never see an image of a food product, Rotenberg said.

She also noted that PBS Kids has Web pages -- Fizzy's Lunch Lab and Don't Buy It -- designed to teach kids about healthy eating and avoiding media influences, respectively.

When it comes to the issue of media influences on children, TV ads have long been under fire for marketing junk food to children and teenagers.

But the Internet has provided a whole new outlet for advertisers -- and companies are expected to keep increasing the proportion of their spending devoted to online marketing, according to Dorfman's team.

The public health implications are serious, Dorfman told Reuters Health in an email, because digital marketing such as what we found on Web sites popular with kids is much different than TV advertising, which caused the alarm in the first place.

Digital marketing, she argued, is immersive, interactive and incessant -- rather than 30 seconds watching a TV commercial, children are spending 20 minutes deeply engaged with the brand.

A recent study found that food manufacturers' use of advergames -- online games that companies use to boost traffic to their Web sites and promote their brands -- may indeed influence kids' eating choices.

When researchers had children play advergames that focused on cookies and chips, the kids wanted those same foods afterward. But when the games featured fruit and orange juice, the children tended to want those foods for a post-game snack.

For the current study, Dorfman and her colleagues assessed the nutritional quality of foods and beverages advertised on the 28 top children's Web sites between July and August of 2007.

Of the 77 products they found, 49 met the foods to avoid criteria set by the Institute of Medicine (IOM), an advisory body to the federal government. Another 23 products fell into the neutral category because they were neither junk foods nor nutritious enough to be encouraged; such products included lower-sugar cereals and certain baked snack foods.

Only five of the advertised products -- including oatmeal, milk and pure fruit juice -- were foods that the IOM encourages children to eat.

Parents should be concerned because much digital marketing flies under their radar, Dorfman said.

But she also asserted that parents should not be given the job of monitoring the ads their kids see online.

The online environment is not like watching TV, something a family might do together, Dorfman said. It's unreasonable, and unfair, she added, to think that parents could monitor every mouse click children make.

Instead, Dorfman argued, food marketers and children's media companies need to adhere to higher nutrition standards for the foods they market to children, especially when they do it out of earshot of parents.

SOURCE: American Journal of Public Health, November 2009.