Glucose is the fuel that allows the brain and nerve system to function. The brain has a high metabolic rate and needs 130-200 grams of glucose per day to function normally. There are relatively few blood capillaries around the brain, therefore oxygen, transported in the blood, is also highly prized by the brain, which is extremely sensitive to anoxia, a lack of oxygen.
As glucose can be produced in the body without oxygen, this makes glucose an ideal energy source for the brain, as fat cannot be produced in the absence of oxygen. It seems that even during periods of starvation, one of the major aims of the body is to supply glucose to the brain. The brain cannot store glucose and therefore depends on glucose from the intake of carbohydrates from your diet. In an extreme situation, if the level of glucose in the blood should fall below a certain level, even for a short space of time, then irreversible brain damage can occur.
