Lactose means milk at its Latin root, adding -ose to indicate sugars. This disaccharide composed of glucose and galactose units is extracted from sweet or sour whey. Lactose is the primary carbohydrate and plays a significant role in milk synthesis. This enzyme draws water into milk formed in mammary epithelial cells and is unique to the mammary gland. This carbohydrate is a digestible source of glucose or energy for mammal neonates. Lactose’s bland flavor lends itself to be used as a carrier and stabilizer of aromas and pharmaceutical products. This sugar also works as a pharmaceutical filler for pills due to its compressibility and low price. While a food product itself, this enzyme is not used in foods due to its inferior solubility to other sugars. Infant formula is the exception to this statement. Certain yeasts can break down lactose for ethanol production. This fact supports using excess lactose from whey production as a possible energy source.