Beta-hydroxybutyrate

Beta-Hydroxybutyrate (BHB) is a ketone body produced by the liver from fatty acids during periods of low food intake, carbohydrate restrictive diets, starvation, prolonged intense exercise, or in untreated type 1 diabetes mellitus. It is one of the three "ketone bodies" – the others being acetoacetate and acetone – and plays a key role in the ketogenic process.

Production and Utilization

Beta-Hydroxybutyrate is synthesized in the liver from acetoacetate through the action of the enzyme beta-hydroxybutyrate dehydrogenase. This process is part of the body's adaptation to energy requirements when glucose availability is low. BHB then travels from the liver to other tissues, where it can be converted back to acetoacetate and then to acetyl-CoA, which enters the citric acid cycle to produce energy.

Physiological Role

BHB serves as an important energy source for the brain, heart, and muscles during periods when carbohydrates are not available. It is more efficient in energy production per unit oxygen consumed than glucose, making it a highly efficient fuel during times of oxidative stress. Additionally, BHB has been found to have signaling functions, influencing gene expression and cellular processes related to inflammation and oxidative stress.

Clinical Significance

Elevated levels of BHB and other ketone bodies can be found in ketoacidosis, a dangerous condition often associated with uncontrolled type 1 diabetes. However, moderate elevation of BHB in the context of ketogenic diets or fasting is considered safe and can have therapeutic benefits. Research is ongoing into the use of BHB in treating neurological diseases, such as Alzheimer's disease and epilepsy, due to its neuroprotective properties.

Measurement

BHB levels in the blood can be measured using specific blood tests, which are useful in diagnosing and monitoring ketoacidosis in diabetic patients. These measurements can also be used to monitor adherence to ketogenic diets.

Supplementation

Exogenous BHB is available as a dietary supplement, often in the form of salts (sodium, potassium, or calcium BHB). These supplements are marketed for enhancing physical performance, mental clarity, and facilitating quicker entry into ketosis. However, the efficacy and safety of long-term BHB supplementation require further research.