nother approach involved showing short television segments about health education, delivered by the vegetable characters, in the school lunchrooms. The third approach combined the banner with the video segments. A control group experienced no marketing interventions.
The researchers found that almost 100% more students took vegetables from the salad bar when exposed to the banners alone. Before the banners, only about 12% of students took vegetables, but after the banners, about 24% of students did.
The banners combined with the videos, however, resulted in a whopping 239% increase in the number of students who visited the salad bar. So before the marketing, only about 10% of students took vegetables, but after, about 34% did.
However, the television segments alone did not have a significant impact on students' eating behaviors, the researchers noted.
"I was surprised to learn that the TV segments weren't effective," Hanks said.
"Based on the results, it seems that the banners were most effective," he added. "They were effective when used alone and carried the effect when used with the TV segments. The banners were most effective since they were placed right at the point of selection. The TVs were placed where space and electricity were available."
In a separate paper
, a Canadian research team analyzed how similar marketing strategies for unhealthy foods and beverages can influence children's eating behaviors. The research was published in the journal Obesity Review on Tuesday.
The researchers identified and reviewed 26 previous studies on children's food preferences and intake after they were exposed to food and non-food advertisements. In total, the studies included almost 6,000 children ranging in age from 2 to 18.
After analyzing the studies, the researchers found that children exposed to the marketing of unhealthy foods consumed significantly more. Being exposed to a five-minute advertisement was linked to eating nearly 4.5 grams more of junk food than otherwise, according to the paper. Similarly, children exposed to ads consumed 30 calories more of junk food than those not exposed to junk food ads.
The researchers also demonstrated that children 8 or younger seemed to be more susceptible to the impact of marketing.
"The findings from this review contribute to the growing body of research suggesting that the marketing of energy-dense, low-nutrition foods and beverages to children contribute to increased consumption of unhealthy calories -- an average of 30 calories more during or shortly after exposure to advertisements -- which puts children at increased risk for obesity and diet-related diseases later in life," said the paper's lead author, Bradley Johnston, director of Systematic Overviews through advancing Research Technology at the Hospital for Sick Children in Toronto and assistant professor at the University of Toronto.
On average, children are exposed to about five food commercials
per hour while watching television, according to a 2010 study published in the American Journal of Public Health
. The majority of those ads tend to feature unhealthy foods
o get children to eat more fruit and vegetables, the Centers for Disease Control and Prevention
advises parents to set an example by eating healthy foods along with their kids, as well as providing fruit and vegetables as snacks and during celebrations. Also, it helps when children work in gardens and grow their own produce.
However, many researchers are eager to see what would happen if more ads focused on healthy foods.
"We all know marketing works," Hanks said.