Protein is one of the three major, or macro, nutrients. Unlike carbohydrates and fats (the other two types of macronutrents), proteins are comprised of nitrogen-containing groups called amino acids. There are about 20 different types of amino acids commonly found in foods. All of them are important for building and maintaining muscle, but 8 are vital. These are what’s known as the Essential Amino Acids (EAAs). Contrary to what most athletes believe, there is no actual requirement for protein; the body simply has a requirement for the eight essentials.
The EAAs cannot be synthesized in any of your tissues, so they must be obtained through high protein foods. Lean meats, fish, poultry, eggs, milk, cheese, and soybeans are good food sources of protein. Powdered whey, casein, egg, and soy proteins offer the same amino acids as whole food sources in more concentrated doses – with lower levels of calories, fat, carbs, cholesterol, and other non-protein ingredients.
Currently the undisputed king of proteins. Here’s why: whey proteins are quickly and easily digested (hence the “fast-acting” description that they’re often given), they are loaded with essential amino acids (EAAs) – including the three branched chain amino acids (BCAAs), and they contain subcomponents (microfractions) that appear to provide benefits above and beyond amino acids and elemental nitrogen. Whey is one of two major dairy proteins and accounts for about 20% of the protein in milk.
Comprising 80% of the protein in milk, casein is the dominant dairy protein. Oft referred to as a “slower-acting” or “time-released” protein, because they are digested and absorbed much more slowly than whey or soy proteins. Casein proteins are especially useful when taken at bedtime and during other prolonged periods without eating.
Milk proteins are pretty much what you’d expect: dried milk with most of the fat and carbohydrate removed. Like liquid moo juice, powdered milk proteins are about 20% whey protein and 80% casein protein, so utilization is somewhere in between the two.
Ask any dietitian, “What’s the best source of protein?” and eggs will probably top the list. In fact, most nutrition textbooks still refer to eggs as the “gold standard” for protein quality. With loads of essential amino acids (EAAs) and some of the highest scores in all measures of protein quality, we’re not going to argue. Naturally dairy-free, eggs are a great alternative to whey, casein, and whole milk proteins for those with milk allergies or severe lactose intolerance.
Vegetarian? Don’t do well with dairy or egg? Go green. Like their animal counterparts, soy proteins contain all of the required amino acids in sufficient amounts to support muscle growth and development.
If you can only afford one type of protein, this is probably the type that you should go with. Combining faster-, intermediate-, and slower-protein sources in one convenient place, blended proteins give you more sustained protein digestion than single-source proteins like whey, casein, egg, or soy.