Benefits of Keto: Glucose VS Ketones in the Brain


Benefits of Keto

Many people find keto for weight loss but stick to the diet because of its numerous cognitive benefits. The human brain thrives on ketones, which is why so many ketogenic dieters report increased focus and mental clarity.  One of the simplest ways to look at the cognitive benefits of keto over a traditional diet is to compare glucose versus ketone metabolism and uptake in the brain.

 

Glucose Metabolism (Glycolysis)

Dietary glucose is obtained through the digestion of carbohydrates in the stomach and through digestion in the small intestine by gastric and pancreatic enzymes. Glucose is further broken down through the process of glycolysis. Through a series of steps, glucose is broken down into pyruvate and acetyl-CoA. Acetyl-CoA enters the TCA cycle (tricarboxylic acid cycle), which is also known as the citric acid cycle (CAC) or Krebs cycle. For every one glucose molecule that undergoes glycolysis, there is a net gain of 2 ATP molecules, 2 NADH molecules, and 2 pyruvate molecules (technically 4 ATP are produced, but 2 are used).

Glucose Transport into the Brain

Glucose is transported in the blood and passes through the blood-brain-barrier via glucose transporters (GLUT) to supply the brain with energy. Both GLUT1 and GLUT3 transport glucose in the brain; however GLUT 3 is the most abundant, making it predominantly response for glucose transport into the brain. Energy for the brain is produced from glucose breakdown and the formation of ATP. 

Ketone Metabolism (Ketogenesis and Ketolysis)

When carbohydrates are restricted and insulin is lowered, fatty acids are mobilized. These free fatty acids (FFAs) are broken down into acetyl-CoA within the liver.  High levels of acetyl-CoA lead to the production of ketone bodies (acetoacetate, acetone, and beta-hydroxybutyrate). This process is known as ketogenesis. Ketones are released by the liver into the bloodstream where they can travel to the brain.

Ketones can then be broken down into acetyl-CoA, which feeds into the TCA cycle to produce energy (ATP). This process is known as ketolysis.

Ketone Transport into the Brain

BHB (beta-hydroxybutyrate) is taken up by the brain via Monocarboxylate Transporters (MCTs, not to be confused with Medium Chain Triglycerides).  BHB is converted into acetoacetate and then into acetoacetyl. Acetyoacetyl can then be converted into acetyl-CoA before entering the mitochondria where it enters the TCA cycle and leads to ATP (energy) production.

 



Want to Know More About the Benefits of Ketones for Your Brain?

Check out the full article along with numerous other research-based articles in Keto Club!

 

References

Hawkins, R. A., & Biebuyck, J. F. (1979). Ketone bodies are selectively used by individual brain regions. Science, 205(4403), 325-327.