Sugars in the brain

Glucose plays one of its most important roles in the body as the primary source of fuel for the brain. However, glucose serves several other important roles in the brain as well. Metabolites of glucose become substrates for neurotransmitter production and alternative energy sources. Also, glucose can be “sensed” by the brain, triggering or inhibiting specialized neurons responding to changes in blood glucose levels and, in turn, affecting peripheral regulation of glucose levels, feeding behavior, and energy expenditure. Sugars other than glucose can also be metabolized and sensed by the brain. As will be discussed later in this chapter, the common dietary additive, fructose, undergoes both alternative metabolism and is sensed differently from glucose by neural tissue, resulting in divergent behavioral consequences.