Brain Responds Differently to Two Kinds of Sugar: Study

Further, administration of fructose directly into the brain provokes feeding in rodents, whereas glucose administered this way promotes satiety, or the feeling of being full. Preliminary studies in people have also shown that glucose reduces activity in the hypothalamus, an event that is associated with metabolic satiety, whereas fructose does not. Using functional magnetic resonance imaging (fMRI), Kathleen Page at the Keck School of Medicine and her colleagues in the Department of Psychology at the University of Southern California extended this work.

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They examined brain responses and motivation to eat when research volunteers viewed images of food (like chocolate cake) after they drank a beverage containing either glucose or fructose. The participants were 24 young men and women, 16 to 25 years of age. They viewed images of food during fMRI scans of their brains and reported how much they wanted to eat. The food cues produced activation in the nucleus accumbens, a part of the brain's "reward circuit", and increased the desire for food. Activation in the nucleus accumbens was greater after consuming the fructose drink compared to the glucose drink.

The fructose drink also resulted in greater ratings of hunger and motivation to eat compared to the glucose drink. These neural and behavioral responses to high-calorie food stimuli could promote eating, and more so after consuming fructose compared to glucose. These studies have important public health implications in a society that is inundated with high-sugar foods and tantalizing food stimuli. They suggest that consumption of fructose may promote overeating.

Source: Eurekalert