Forget the sweet tooth, eyes reveal a taste for sweets

If chocolate brownies make your eyes light up, there's a chemical reason: Rich, sugary treats trigger a surge of dopamine, the brain hormone associated with pleasure and addiction, that can be measured in the retina.

A new study published in the journal Obesity used a novel method-electroretinography (ERG), a tool normally used by ophthalmologists to assess retinal damage-to examine what makes some foods so irresistible to some people.

New way to look at dopamine

Drexel University nutritionist Jennifer Nasser came up with the groundbreaking idea of using ERG to assess the connection between food and dopamine.

After reading about the use of ERG in studies of cocaine addicts, Nasser was struck by the idea that it could also be used in the context of obesity research, kazinform has learnt from National Georgraphic.

"I've always wanted to be able to measure dopamine response to food, but other methodologies are either extremely invasive-like a spinal tap-or extremely expensive, like a PET scan, which can cost $2,000 or more a session," Nasser said. "Electroretinography is actually a very old clinical procedure that's much simpler; it's something you could get done at the eye doctor's office."

Scientists already knew that light activates dopamine neurons in the retina, and that consuming sugar and fat releases dopamine in the so-called mid-brain system. But until now, those two systems were thought to be unrelated, said Nasser.

"Many retinal experts told me that using ERG in this way probably wouldn't work," she said, but when she connected the conclusions of several other studies involving dopamine in both the brain and eye, "it just seemed logical."

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