Using human milk as the nutritional standard, formula manufacturers follow a basic recipe that includes proteins, fats, carbohydrates, vitamins, minerals, and water. They combine various ingredients so that the nutrients in artificial baby milks follow the same rough proportions as human milk. The big difference between formulas is the different sources of these elements – cow’s milk, soybeans, or something else. Most formulas are cow’s-milk based, meaning that the basic nutritional building blocks of proteins, fats, and carbohydrates are taken from this nutritional base. Cow’s milk contains most of the nutrients necessary for adequate infant nutrition, although not in quite the proper proportions. Soybeans are also a ready source of certain nutrients necessary for human nutrition. Formula manufacturers start with the basic nutritional elements in cow’s or soy milk and add ingredients until the mixture approximates human milk as closely as possible. They adjust levels of carbohydrates, proteins, and fat and add vitamins and minerals.