In the fed state, which nutrient is primarily used by the brain for energy?

In the fed state, which nutrient is primarily used by the brain for energy?

• A. Fatty acid
• B. Lactic acid
• C. Glucose
• D. Ketone bodies

Answer: (C)

In the fed state, glucose is the primary nutrient used by the brain for energy because it is a simple sugar that can be readily accessed from the bloodstream after carbohydrate consumption. The brain has a high demand for energy, and glucose is the most efficient and preferred source for this organ. During this state, insulin is released in response to elevated blood glucose levels, facilitating the uptake of glucose into cells, including neurons. While fatty acids and ketone bodies can serve as energy sources, they are not the main fuel utilized by the brain under normal circumstances. During periods of prolonged fasting or carbohydrate restriction, the brain can adapt to using ketone bodies, but this adaptation occurs outside the fed state. Lactic acid, produced during anaerobic metabolism, is generally not a significant energy source for the brain and is instead a byproduct of glycolysis. Thus, glucose remains the primary fuel for the brain when nutrients are abundant in the fed state.

In the fed state, glucose is the primary nutrient used by the brain for energy because it is a simple sugar that can be readily accessed from the bloodstream after carbohydrate consumption. The brain has a high demand for energy, and glucose is the most efficient and preferred source for this organ. During this state, insulin is released in response to elevated blood glucose levels, facilitating the uptake of glucose into cells, including neurons.

While fatty acids and ketone bodies can serve as energy sources, they are not the main fuel utilized by the brain under normal circumstances. During periods of prolonged fasting or carbohydrate restriction, the brain can adapt to using ketone bodies, but this adaptation occurs outside the fed state. Lactic acid, produced during anaerobic metabolism, is generally not a significant energy source for the brain and is instead a byproduct of glycolysis. Thus, glucose remains the primary fuel for the brain when nutrients are abundant in the fed state.