3-Hydroxybutanoic acid calcium salt, also known as calcium beta-hydroxybutyrate, is a compound used primarily as a dietary supplement. It provides a source of calcium for bone health and beta-hydroxybutyrate, a ketone body that supports ketosis for applications in weight management, athletic performance enhancement, and therapeutic uses in conditions like epilepsy, Alzheimer's disease, and metabolic disorders. In the biomedical field, its biocompatible and biodegradable properties make it suitable for drug delivery systems and tissue engineering. It also serves as a component in animal feed to improve nutritional value and growth. While 3-hydroxybutyric acid (the parent compound) is a key monomer in producing biodegradable polyhydroxyalkanoates (PHAs), the calcium salt may be used in related biotechnological processes or as a precursor. Its eco-friendly profile supports sustainable applications in nutrition and medicine.