This is a question I am constantly asked; which kind of protein should I consume to help build muscle and lose weight. With so many options out there, ranging from soy protein and animal protein, to supplemental proteins like whey and casein. When looking at a protein source, there are several things to keep in mind. One is the completeness of the amino acid profile, as well as the digestibility of the protein.
Animal protein, widely considered the best protein available, has both a complete amino acid profile, as well as easy digestibility. Amino acids are known as the building blocks of muscle. There are 20 amino acids that help to build a complete protein, and these are broken down into both essential and non essential amino acids. Essential amino acids are acids that must be obtained from food, because they cannot be readily produced in the body. Non-essential amino acids can be synthesized, as long as a diet contains nitrogen. A complete protein contains all 20 essential and non essential amino acids (Liska, 2004). This is why animal protein is generally preferred over plant protein when looking at muscle building capability. Dairy protein is usually easier to digest than meat protein, when looking at animal protein. Here is a chart published in the journal of sports science and medicine ranking different proteins (Hoffman, 2004). When looking at different types of animal proteins, casein, or milk protein, is generally considered the gold standard of proteins. Studies have shown casein protein to provide the greatest increases in muscle mass and protein synthesis when used over a period of time (Hoffman, 2004). For a more in depth look at proteins, here is an excellent article discussing this topic in depth. If you are trying to increase your casein protein intake, but do not want to increase milk intake, casein protein is readily available in supplement form. Look for pure casein protein, without any added sugars or fillers. The other milk protein, whey, is also available in many supplement forms.
If you are vegetarian, or have difficulty digesting animal proteins, soy protein is the next best thing. When compared to casein protein (considered the gold standard of protein), soy protein has been measured as high as 92% as effective as casein protein, which is pretty good for a plant protein (Liska, 2004). Soy based foods, such as tofu and soy flour, are also easily digested by a majority of the population.
Hoffman, J. R., & Falvo, M. J. (2004). Protein–which is best?. Journal of sports science & medicine, 3(3), 118.
Liska, D. (2004). Clinical nutrition: A functional approach (2nd ed.). Gig Harbor, Wash.: Institute for Functional Medicine.