Junk food is a significant contributor to the skyrocketing rates of childhood obesity, type 2 diabetes, high cholesterol, and high blood pressure. Children are exposed to food advertising - including junk food commercials - multiple times a day. Researchers have found that these advertisements directly influence children's food choices and brain activity, and they may be a factor in overeating and the associated health risks.

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TV commercials may make children more inclined to reach faster, more impulsive decisions regarding their food choices.

The food industry spends around $1.8 billion a year marketing products to children and adolescents. Children between the ages of 2-5 years are estimated to view more than 1,000 advertisements per year, and teenagers almost 2,000.

Food marketing is cited as a substantial environmental factor in food choices and overeating, and, as a result, obesity, and TV advertising and branding have been shown to affect both food familiarity and preference.

Previous research indicates that children who view advertisements are more likely to prefer branded foods than children not exposed to advertisements. Behavioral studies have reported an association between receptivity to food commercials and the amount of food consumed.

Other studies have observed that children who are overweight may be more responsive to food branding and, as a result, are at a greater risk of being influenced by marketing. Research has demonstrated a relationship between marketing junk foods and an increased risk of childhood obesity.

A previous study by lead study author Amanda S. Bruce, Ph.D., assistant professor of behavioral pediatrics at the University of Kansas Medical Center, documented individual differences in brain activation in response to food advertising cues, such as fast food brand logos.

When observing food brand logos, obese children demonstrate reduced neurofunctional reactivity in the prefrontal cortex - a cortical region known to be associated with self-control.

Decision processes and brain activity monitored during food selections

In the new study, Bruce, together with researchers from the University of Kansas Medical Center and the University of Missouri-Kansas City, aimed to examine children's food decision processes and brain activity during active food selections.

Specifically, the team wanted to find out if food choices and brain activity were altered after viewing food commercials.

The research, published in The Journal of Pediatrics, centered on 23 children between the ages of 8-14 years. The children provided taste and health ratings for 60 food items based on how tasty and healthy they thought they were.

Bruce and colleagues studied the children's brain activity - with the use of functional magnetic resonance imaging (fMRI) - while making food choices after watching food and non-food TV commercials.

"For brain analyses, our primary focus was on the brain region most active during reward valuation, the ventromedial prefrontal cortex," says Bruce. During the brain scan, the children were asked whether they wanted to eat the food items shown to them immediately after the commercials.

Watching food commercials influenced children's taste preferences

Results highlighted that, overall, children's decisions on the foods they wanted to eat were driven by tastiness rather than healthfulness. The taste of foods was even more of a factor after watching food commercials - that is, children favored specific foods and placed an even greater emphasis on taste attributes of these foods.

The researchers found that watching food commercials changed the way children assess the importance of taste when making food choices. The authors write: "It is possible that the food commercials prime children to focus on the more hedonic aspects of food."

"Food commercials may prompt children to consider their liking and wanting of specific food items, irrespective of the lack of any health benefits. This increased emphasis on taste may make it even more difficult for relevant caregivers to encourage healthy food choices. This evidence has implications for policies related to food advertising to children," they add.

When compared with non-food commercials, the vmPFC area of the brain that is associated with reward and value assessment showed increased activity at the time of food choice after watching food commercials. This activity indicates that food commercials stimulate children's brains in a way that non-food commercials do not.

Also, the more hunger the child reported, the greater the vmPFC activity, suggesting that when children are hungry, the effect of food commercials on brain activity may be particularly noticeable.

Most kids' food commercials advertise foods high in fat, sugar, sodium

Obesity has more than doubled in children and quadrupled in adolescents over the past 30 years, according to the Centers for Disease Control and Prevention (CDC).

The percentage of American children aged 6-11 years who were obese increased from 7-18 percent between 1980-2012, and similarly in adolescents of 12-19 years, increasing from 5-21 percent in the same period. The exploitative nature of food advertising directed at children prompts concern about the potentially harmful effects food commercials may have on children's health.

According to the American Heart Association, although many countries across the world tightly control or ban food advertising and marketing aimed at youth, this is not the case in the U.S.

Children and teenagers spend more than $180 billion each year, and they influence their parents' spending for another $200 billion per year. The American Heart Association notes that 84 percent of foods advertised as healthy do not meet basic nutritional standards, and 86 percent of food advertisements viewed by children are for products high in fat, sugar, or sodium.

The study results show that watching food commercials may change the way children value taste, increasing the potential for children to make faster, more impulsive food choices.

"Food marketing may systematically alter the psychological and neurobiological mechanisms of children's food decisions."

Amanda S. Bruce, Ph.D.

Future studies by Bruce and co-workers may focus on brain activity differences between lean and overweight or obese children when making food decisions after watching commercials, and the distinction between healthy and unhealthy food choices.

Read about how children between the ages of 2-19 years are failing to meet cardiovascular health guidelines.