What is the primary source of energy for the brain?

The primary source of energy for the brain is glucose. The brain is an organ with high energy demands, utilizing about 20% of the body's total energy consumption despite representing only about 2% of body weight. Glucose, a simple sugar, is critical for the brain's function because it easily crosses the blood-brain barrier and is efficiently metabolized to produce ATP, the energy currency of cells.

While fatty acids can serve as an energy source for other tissues, especially during prolonged fasting or low-carbohydrate diets, the brain primarily relies on glucose derived from carbohydrates in the diet. Proteins are primarily used for tissue repair and growth rather than as a direct energy source for the brain. Vitamins play supportive roles in metabolic processes but do not serve as energy sources themselves. Therefore, glucose stands out as the most essential nutrient for enabling the brain to perform its wide array of functions effectively.