High-fructose corn syrup is listed as an ingredient on a can of soda.(Photo: Matt Rourke, AP)
This is your brain on sugar - for real. Scientists have used imaging
tests to show for the first time that fructose, a sugar that saturates
the American diet, can trigger brain changes that may lead to
After you drink a fructose beverage, the brain doesn't
register the feeling of being full as it does when simple glucose is
consumed, researchers found.
It's a small study and does not prove
that fructose or its relative, high-fructose corn syrup, can cause
obesity, but experts say it adds evidence they may play a role. These
sugars often are added to processed foods and beverages, and consumption
has risen dramatically since the 1970s along with obesity. A third of
U.S. children and teens and more than two-thirds of adults are obese or
All sugars are not equal - even though they contain
the same amount of calories - because they are metabolized differently
in the body. Table sugar is sucrose, which is half fructose, half
glucose. High-fructose corn syrup is 55% fructose and 45% glucose. Some
nutrition experts say this sweetener may pose special risks, but others
and the industry reject that claim. And doctors say we eat too much
sugar in all forms.
For the study, scientists used magnetic
resonance imaging, or MRI, scans to track blood flow in the brain in 20
young, normal-weight people before and after they had drinks containing
glucose or fructose in two sessions several weeks apart.
showed that drinking glucose "turns off or suppresses the activity of
areas of the brain that are critical for reward and desire for food,"
said one study leader, Yale University endocrinologist Robert Sherwin.
With fructose, "we don't see those changes," he said. "As a result, the
desire to eat continues - it isn't turned off."
said Jonathan Purnell, an endocrinologist at Oregon Health &
Science University, is that the imaging results mirrored how hungry the
people said they felt, as well as what earlier studies found in animals.
implies that fructose, at least with regards to promoting food intake
and weight gain, is a bad actor compared to glucose," said Purnell. He
wrote a commentary that appears with the federally funded study in
Wednesday's Journal of the American Medical Association.
now are testing obese people to see if they react the same way to
fructose and glucose as the normal-weight people in this study did.
to do? Cook more at home and limit processed foods containing fructose
and high-fructose corn syrup, Purnell suggested. "Try to avoid the
sugar-sweetened beverages. It doesn't mean you can't ever have them,"
but control their size and how often they are consumed, he said.