MONDAY, March 4, 2019 (HealthDay News) -- When a social media "influencer" hawks junk food, young kids may be easily won over, a new study suggests.
British researchers found that when children saw images of two famous YouTube "vloggers" simply holding junk food, they immediately showed a craving for cookies and candy.
Unfortunately, they were not similarly swayed by images of those online stars with healthy foods.
Experts said the findings point to the power of an insidious form of junk food marketing, in which companies pay social media influencers to feature their products.
"Most parents are surprised this exists," said Jennifer Harris, of the University of Connecticut's Rudd Center for Food Policy and Obesity. "They often have no idea how targeted their kids are when they're online."
Harris, who was not involved in the study, conducts research on food marketing to kids.
She said that in comparison to traditional advertising, it's difficult to study the influence of social media on kids' food preferences.
"There isn't a lot known about it, because it's hard to track what kids are seeing on social media," Harris explained.
So she said she was "excited" to see the new findings, published online March 4 in the journal Pediatrics. They show, through an experimental design, how social media images can immediately influence kids' food choices, Harris said.
For the study, researchers from the University of Liverpool created phony Instagram accounts that appeared to belong to two popular YouTube video bloggers.
Both vloggers -- unidentified by the researchers -- are young adults who are popular with British children and have 4 to 12 million subscribers to their YouTube channels and their real Instagram accounts.
Researchers then recruited 176 girls and boys aged 9 to 11 and randomly assigned them to one of three groups.
All of the kids viewed a handful of images from the mock Instagrams: One group saw images in which the vloggers were holding healthy food, like fresh fruit; a second group saw them holding chocolate cookies or other junk food; the third group saw them holding nonfood items, such as sneakers.
Afterward, children were offered a selection of snacks and told they could eat as much as they wanted. The snacks included candy, chocolate, carrot sticks and grapes.
Overall, the study found, kids who viewed the junk food images were more likely to munch on candy and chocolate: They ate 32 percent more calories from those foods than their peers who'd viewed nonfood images -- and 20 percent more than kids who'd seen pictures of healthy food.
In contrast, kids in the healthy-snack group were unimpressed by the images: They ate no more carrots and grapes than their peers did.
That may be because children simply have an "innate preference" for sugary, fatty, salty treats, according to lead researcher Anna Coates, a doctoral student in psychological sciences.
"Unlike adults," she said, "children are less motivated to resist food marketing, as they're not driven by long-term health goals."
Coates said it's important for parents to know this type of marketing exists.
"Food marketing embedded within a YouTube video is more discreet and targeted than other forms, and therefore, potentially more powerful," she said. "Parents could talk to their children about why they think social media influencers are paid to show these products in their vlogs."
Harris agreed that parents should talk about the coziness between marketers and social media stars. But she also doubted how much good it would do.
"Research suggests that even when kids know, they don't really care," Harris said. "What's most important to them is what their friends are doing."
Plus, she said, "when you're 13, you're not thinking about getting heart disease 30 years from now."
What about regulation? It's tricky, Coates said. YouTube, Instagram and other social media have minimum age requirements for account holders -- so junk food marketers can deny that their social media efforts target kids.
The reality is that children lie about their ages and create accounts anyway, Coates said. Or they simply view public content on the sites.
Surveys of U.K. children show that half of 8- to 11-year-olds use Instagram, while more than 80 percent of 5- to 15-year-olds use YouTube, according to Coates' team.
In the United States, Harris said, companies self-regulate, and they refrain from advertising on children's TV networks, for example. But kids are still awash in ads directed at a broad audience.
The American Academy of Pediatrics has advice for parents on digital media use.