There are two ways to answer this question- one could consider the fuel consumed on a daily basis by our brain or one could take a longterm perspective of overall brain health.
From day to day, our brains primarily utilize glucose as fuel. Glucose is a simple sugar that is the most convenient form of fuel for cells. Although the brain is only two percent of the body’s total weight, it consumes an average of 70 percent of the body’s glucose, which comes as no surprise because we have up to 100 billion energy-hungry neurons in our brains. Glucose, a simple sugar, is absorbed by brain cells directly from the blood stream. Glycogen, a larger carbohydrate, can be broken down by the liver and kidney to release more glucose into the bloodstream if necessary. The body continually adapts its metabolism to ensure that plenty of glucose is available for the brain. During times of extreme stress, blood flow is decreased to muscles and other organs that also consume glucose to ensure that the brain has a continuous supply of glucose.
The second way to address this question is from a longterm perspective. As we age, our brains must protect themselves from free radicals that are generated during normal cellular metabolic processes. During stressful times, our bodies are exposed to greater loads of free radicals. Throughout our lives, brain cells can be damaged by free radicals. It is thus important to consume foods with antioxidants because antioxidants protect brain cells from free radicals. One food that is especially high in antioxidants is blueberries. It has been demonstrated that diets high in blueberries may assist in rapid recovery from severe oxidative brain injury (Stromberg I, et al.), may reverse age-related cognitive decline (Lau FC, et al.), and help with memory (Andres-Lacueva C, et al.). Other fruits high in polypheonls, the specific antioxidant component in blueberries, are kiwis, plums, cherries, blackberries, currants and apples.
Stromberg I, et al. Neurol. 2005 Dec;196(2):298-307.
Lau FC, et al. Neurobiol Aging. 2005 Dec;26 Suppl 1:128-32.
Andres-Lacueva C, et al. Natr Neurosci. 2005 Apr;8(2):111-120.