Researchers from the University of Oslo surveyed more than 5,000 Norwegian 15- and 16-year-olds on their soda consumption habits, then questioned them on mental health, including questions on hyperactivity and distress. The researchers found that the teens with the most mental health problems were the teens who reported the highest sugary soda consumption.
"There was a strong association between soft drink consumption and mental health problems among Oslo 10th graders," the researchers' report stated. "This association remained significant after adjustment for social, behavioral and food-related disorders."
The researchers -- led by Dr. Lars Lien -- found that teens who reported skipping breakfast and lunch were some of the heaviest consumers of sodas, with most students reporting between one and six weekly soft drink servings. Though moderate drinkers were less likely to display mental disorders than those who drank no soft drinks, the researchers reported clear links between the worst mental health sufferers and the highest soda consumers.
For example, Lien's team found a direct linear relationship between the high soft drink consumption and hyperactivity. The more sodas teens drank, the more hyperactivity symptoms they displayed. Teens who drank four or more soft drinks per day displayed the worst mental health symptoms, with 10 percent of boys and 2 percent of girls reporting consuming that much daily soda.
Norwegian authorities recommend that only 10 percent of daily calories come from sugar, but Lien's team found that at least 25 percent of Norway's teen boys were getting that much sugar from soft drinks alone.
"One simple and effective measure to reduce soft drink consumption in this age group would be to remove soft drink machines from schools and other public places where adolescents gather," the researchers wrote.
Consumer advocate Mike Adams, author of "The Five Soft Drink Monsters" -- a book aimed at helping consumers kick the soda habit -- calls Lien's study "the soft drink industry's worst nightmare" and favors removing soda vending machines from schools.
"[The study] establishes a scientific link between the consumption of high-fructose corn syrup in soda and abnormal mental states in children," Adams said. "In the world of nutrition, we've known this for a long time, but the soda industry has vigorously fought any such associations, claiming sodas are harmless. Today we know that simply isn't true."