MOST of us accept that the capacity for exercise can be enhanced by increasing the delivery of glucose or oxygen to muscles. Could the same principles be applied to brain function? At the Human Cognitive Neuroscience Unit (HCNU) we have been investigating the possibility that cognitive performance can be improved by increasing the availability and delivery of the brain’s basic fuels. The human brain is excessively greedy. Contributing only 2 per cent to the average person’s weight, it is constantly burning away some 20 per cent of the body’s calories, making it easily the most energetic organ. The energy supply of the body originates from oxygen (breathed in from the air) and glucose (from food). These circulate in the blood until they are delivered, sushi-like, to active tissue for immediate use or storage. Unfortunately the brain has a fairly serious design fault. Despite requiring more than its fair share of energy, it cannot store glucose. This means that it relies on a constant supply of glucose through its rich blood supply.