What is the primary source of energy for the brain?

The primary source of energy for the brain is carbohydrates. The brain relies on glucose, which is a simple sugar derived from carbohydrates, as its main fuel source. Glucose is readily accessible in the bloodstream and can efficiently cross the blood-brain barrier, making it an indispensable substrate for neuronal activity.

While proteins and fats do play important roles in overall nutrition and cellular function, they are not the primary energy source for the brain. Proteins are mainly used for building and repairing tissues, while fats serve as a long-term energy storage form and contribute to cellular structures and hormone production. Fiber, on the other hand, is primarily associated with digestive health and does not provide energy directly to the brain. Therefore, while the body can utilize fats and proteins in various metabolic pathways, carbohydrates—specifically in the form of glucose—are essential for meeting the brain's immediate energy demands.