Oct. 16 (UPI) -- Diets high in sugar may increase a person's risk for developing attention deficit hyperactivity disorder, bipolar disorder and aggressive behaviors, according to a report published Friday by the journal Evolution and Human Behavior.
Researchers from the University of Colorado Anschutz Medical Campus suggest that fructose, a component of sugar and high-fructose corn syrup, and uric acid, a fructose metabolite, may work to bring about the onset of these disorders in those genetically predisposed to them.
By lowering energy in cells, fructose "triggers a foraging response similar to what occurs in starvation," which effectively stimulates behaviors such as risk taking, impulsivity, rapid decision making and aggressiveness, the researchers said.
This foraging response shares similarities with behavioral disorders such as ADHD, as well as bipolar disorder and aggressive behavior, they said.
"There have been many reports suggesting that sugar or other added sweeteners such as high-fructose corn syrup may be able to cause or aggravate various behavioral disorders," study co-author Dr. Richard Johnson told UPI.
"The evidence is based on the unique ability of fructose to lower energy that triggers a foraging type of response," said Johnson, a professor at the University of Colorado School of Medicine.
The theory is based on "an evolutionary-based survival pathway" used by animals to protect against starvation, according to Johnson and his colleagues.
Historically, animals and humans used this response for survival, understanding that they needed to take certain risks to obtain food and avoid starvation and death, the researchers said.
However, this survival pathway is now activated by the metabolism of fructose, leading to the storage of fat in the liver and blood, the development of insulin resistance and a decrease in energy expenditure, earlier research by Johnson and his colleagues suggested.
The introduction of refined sugar and high-fructose corn syrup into the human diet has led to a significant increase in fructose intake over the past 300 to 400 years, and Johnson and his colleagues argue that this level of intake is higher "than nature intended."
In addition to fueling epidemics in obesity and diabetes, high-fructose intake can lead to problem behaviors, as human cells seek to restore their lost energy.
The new report describes how high amounts of fructose found in refined sugars in the typical Western diet may contribute to the development of behavioral disorders.
Sugar does not cause these behaviors, however, as it's just a contributing factor, researchers emphasized.
"The identification of fructose as a risk factor does not negate the importance of genetic, familial, physical, emotional and environmental factors that shape mental health," Johnson said.
Conditions such as ADHD and bipolar disorder are genetic -- meaning they're passed from parent to child -- but they also have some "environmental components," according to Dr. L. Eugene Arnold, emeritus professor of psychiatry at Ohio State University.
"Physical and mental health ... impact each other," said Arnold, a resident expert with Children and Adults with Attention-Deficit/Hyperactivity Disorder, or CHADD, an education and advocacy organization for people with the condition and their caregivers.
Currently, CHADD doesn't offer guidance with regard to diet. However, the organization does cite research noting links between sugar intake and the worsening of ADHD symptoms.
With that in mind, Arnold recommends a diet built around "natural, whole foods," such as the Mediterranean diet.
"A rule of thumb is if the list of ingredients on a food product label is so long you don't want to read it, don't buy it," he said.
More research is needed to investigate the role of sugar and uric acid on mental health, especially with drugs designed to inhibit fructose metabolism for the treatment of diabetes and metabolic syndrome on the horizon, Johnson said.
For now, "reducing intake of sugar and high-fructose corn syrup, especially sugary beverages, may be of additional benefit in preventing or helping behavioral disorders such as ADHD and bipolar disorder," he said.