December 10, 2008 / 8:36 PM / 11 years ago

Sugar can be addictive, at least in rats

CHICAGO (Reuters) - A study of rats offers scientific proof for what many dieters already know: Sugar can be addictive.

A man repacks sugar in packets on sale for 6.70 pesos ($0.36) on a table at a public market in Taguig City Metro Manila August 27, 2008. REUTERS/Cheryl Ravelo

“Bingeing on sugar can act on the brain in ways very similar to a drug abuse,” said Bart Hoebel of Princeton University in New Jersey, who presented his findings on Wednesday at a meeting of the American College of Neuropsychopharmacology in Scottsdale, Arizona.

He said bingeing on sugar water produced behavioral and even neurochemical changes in rats that resembled the changes produced when animals or people take substances of abuse.

“These animals show signs of withdrawal and even long-lasting aftereffects that might resemble craving,” Hoebel told reporters in a telephone briefing.

In one experiment, lab rats were fed a breakfast of sugar water after a nighttime fast for a period of three weeks.

“What we discovered is this releases a surge of (the brain chemical) dopamine. It is in a part of the brain involved in motivation and reward, the nucleus accumbens,” Hoebel said.

“It’s been known for a long time that drugs of abuse release or increase the levels of dopamine in that part of the brain. Here sugar is doing something drugs of abuse are famous for doing,” he said.

He said it does not appear to be the sugar per se, but the act of bingeing on sugar that has the effect.

In another experiment, rats fed this way were then denied sugar for several weeks. When they were allowed to have sugar again, they consumed more of it than before.

“It’s almost as if they are craving the sugar,” he said.

When Hoebel’s team offered alcohol to the rats instead of sugar water, the sugar-fed rats drank more than a normal rat would. And they also showed signs of hyperactivity when given what would normally be an innocuous dose of amphetamine.

“We don’t know about people yet,” Hoebel said.

“The implication is that there is a link from traditionally defined substance abuse disorders such as drug addiction and the development of an abnormal desire for a natural substance, in this case, sugar,” he said.

He said the findings could have implications for humans with eating disorders, such as binge eating or bulimia.

Melanie Miller, a spokeswoman for the Sugar Association, an industry group, said there is currently no compelling evidence that sugar is addictive in humans.

The study was funded by the National Institute of Drug Abuse and the National Institute of Mental Health.

Editing by Maggie Fox

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