What Is a Milk Protein Isolate?

As one of three forms of casein protein, milk protein isolate occurs naturally in cow's milk and includes a combination of casein and whey proteins. Casein protein composes about 80 percent of the protein in cow's milk, while whey protein makes up the remaining 20 percent.

Sources

• Many different products in addition to cow's milk include milk protein isolate as an ingredient, including protein bars, shakes, supplements and powders.

Absorption

• Casein protein synthesizes in the body much more slowly than whey protein, taking up to seven hours to fully release into the blood compared with about one hour for whey.

Usage

• Many people use casein protein that includes milk protein isolate as a diet supplement or meal replacement. In particular, this type of protein helps bodybuilders and other people trying to build and maintain lean muscle mass. To get the most out of the slow protein release, use this form of protein at night or if it will be many hours until another meal.

Quality

• The ratio of casein to whey protein corresponds to the quality of milk protein isolate. The highest quality milk protein isolate combines proteins with a ratio of 80 percent casein to 20 percent whey. Plain cow's milk naturally contains this high-quality ratio.

Tips

• Supplements and other products containing casein proteins like milk protein isolate may contain less than optimum ratios of casein to other types of proteins. Buyers should read ingredient labels carefully to verify quality and protein types.