A new study in the Journal of the American Medical Association is stirring reaction from stakeholders in the corn industry as it claims that fructose spurs hunger and increases weight gain.
The study, "Effects of fructose versus glucose on regional cerebral blood flow in brain regions involved with appetite and reward pathways," claims a link between giving subjects doses of fructose or doses of glucose and then monitoring blood flow to the brain and brain activity that dictates hunger.
The study was conducted on 20 subjects. Each one was given 75 grams of either fructose or glucose in one sitting. The Corn Refiners Association says this amount of fructose represents 300 kcals, which is above the 95th percentile population level recommended for the entire day. Additionally, the subjects had fasted overnight before receiving the fructose or glucose.
But, Dr. James Rippe, professor of Biomedical Sciences at the University of Central Florida, says to consume that amount of sugar in one sitting after a fast is "highly unusual."
The professor works also as a consultant to the Corn Refiners Association. He says the design of the study lacks practicality.
"When consumed together, as they are almost always are, fructose and glucose balance each other out and would likely have no effect on normal hypothalamic blood flow," Rippe said. "What we really need are real world studies where fructose and glucose are consumed together rather than artificial ones where fructose and glucose are consumed separately. Any suggestion that this artificial experiment has implications for human nutrition or obesity is unwarranted speculation."
In an editorial regarding the study release, Dr. Jonathan Purnell, and Dr. Damien Fair of Oregon Health and Science University said that the findings support "conceptual framework" that when the brain is exposed to fructose, neurobiological pathways involved in appetite regulation are modulated, thereby promoting increased food intake.
Purnell and Fair note also that the study is called a "proof-of-concept" study, or a study that uses "experimental conditions that provide maximal contrast between the intervention and control conditions so as to increase the likelihood of finding differences."
So, Rippe again addressed the study design.
"It is important that studies focusing on obesity and food consumption mirror real world experiences as much as possible. By failing to do so, we really gain very little practical insight," he noted.