Protein, carbohydrates and fats are the three major nutrients. Unlike carbohydrates and fats, proteins are comprised of nitrogen-containing groups called amino acids. There are about 20 different types of amino acids found in foods. All are important for building and maintaining muscle, but eight, known as essential amino acids (EAAs), are vital.
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, however, 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 great 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.
The current undisputed king of proteins: whey proteins are quickly and easily digested. They are loaded with essential amino acids. Whey is one of two major dairy proteins and accounts for about 20% of the protein in milk.
The dominant dairy proteins: casein proteins make up 80% of the protein in milk. They are often 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 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.
Most dietitians and nutrition textbooks view eggs as the “gold standard” for protein quality. Eggs are loaded with EAAs and have some of the highest scores in all measures of protein quality. Naturally dairy-free, eggs are a great alternative to whey, casein, and whole milk proteins for those with milk allergies or severe lactose intolerance.
For vegetarians or those who don’t consumer dairy or eggs, soy protein is a great alternative. 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.