Twenty healthy volunteers were randomized into two groups: group A received 300 mL of 22.5% glucose and group B received 300 mL of 22.5% fructose. The solution was consumed after 8 hours of overnight fasting, the repeated with the opposite solution after a 1 week washout period. At each intervention venous blood was collected at 0, 0.5, 1, 2 and 3 hours, ad blood-pressure was recorded at 0, 1, 2, and 3 hours.

Nerve terminals were prepared from rat forebrains and purified synaptosomes were exposed to [U14C]fructose or [U14C]glucose for 10 minutes leading to the selective labeling of glutamate over aspartate and GABA, and Alanine. [U-14C]Fructose shoed a preference for labeling glutamate more strongly, and aspartate and GABA less strongly, than did [U-14C]glucose. Thus, the distribution of label between glutamate, aspartate, and GABA was significantly different in synaptosomes exposed to [U-14C]fructose or [U-14C]glucose, as reflected in an aspartate/glutamate labeling ratio of 0.07 and 0.53 and a GABA/glutamate labeling ratio of 0.03 and 0.36 for [U14C]fructose- and [U14C]glucose-exposed synaptosomes respectively. The increased labeling of glutamate indicates increased uptake of fructose into nerve terminals and oxidative fructose metabolism in these structures.