Abstract - Buttermilk, a traditional dairy product obtained either as a by-product of butter churning or through fermentation of milk with lactic acid bacteria, has long been valued for its nutritional, functional, and cultural significance. Modern research highlights its rich composition of proteins, phospholipids, and bioactive compounds that contribute to digestive health, cholesterol reduction, and improved lactose tolerance. Cultured buttermilk, in particular, serves as a natural probiotic, enhancing gut microbiota and immune function. Beyond its health benefits, buttermilk exhibits unique emulsifying and stabilizing properties, making it a versatile ingredient in bakery, confectionery, and dairy industries. In many cultures, especially in India, buttermilk (chaas) is consumed as a refreshing beverage, often spiced with herbs, and plays a role in traditional wellness practices. This paper reviews the compositional attributes, functional applications, and health-promoting potential of buttermilk, while also exploring its cultural relevance and sustainability as a dairy by-product.

Keywords- Bioactive compound, Probiotic, Electrolytes, Gut, Microbiota.