Whey and casein have different amino acid profiles and digestion rates and, as a result, have different metabolic effects on the body. Protein is available in a variety of dietary sources. These include animal and plant-based foods, as well as the highly commercialized sports supplement industry. In the next section, plant and animal proteins, such as whey, casein, and soy, will be explored.
Determining the effectiveness of a protein is achieved by determining its quality and digestibility. Quality refers to the availability of the amino acids it provides, and digestibility considers how the protein is best used. Generally, all animal protein sources in the diet are considered complete proteins. That is, a protein that contains all the essential amino acids.
Plant-based proteins are incomplete because they generally lack one or two essential amino acids. Therefore, a person who wants to obtain their proteins from plant sources (that is, vegetarian) will need to consume a variety of vegetables, fruits, cereals and legumes to ensure the consumption of all the essential amino acids. As such, people can achieve the necessary protein requirements without consuming beef, poultry, or dairy products. Protein digestibility ratings generally involve measuring how the body can efficiently use dietary sources of protein.
In general, vegetable protein sources do not score as high in terms of biological value, net protein utilization, PDCAAS and protein efficiency ratio as animal proteins. There are many other differences between proteins besides essential amino acids. Protein sources react differently in the body depending on unique absorption rates and different levels of essential and non-essential amino acids. Therefore, the concern about the increased risk of cardiovascular disease due to protein-rich diets seems to be unfounded.
Since protein powders are considered a supplement and, therefore, their content is not regulated by the FDA, look for one that is labeled as certified by third parties. Glutamine and leucine play important roles in the metabolism of muscle proteins, but casein contains 11.6 and 8.9 g of these amino acids, respectively, while whey contains 21.9 and 11.1 g of these amino acids, respectively. Incomplete proteins are not inferior to complete proteins, but they must be combined with another protein source to contain sufficient amounts of essential amino acids. With the right combination of sources, plant proteins can provide benefits similar to those of animal proteins.
Plant-based protein powders can be adapted to different lifestyles and to people with dietary restrictions. The denaturation of proteins involves breaking their structure and losing peptide bonds and reducing the effectiveness of the protein. Munger and colleagues (199) also reported a 69% lower risk of hip fracture due to increased animal protein intake in a large postmenopausal population (32,000). Despite the prevalence of protein-rich diets in athletic and sedentary populations, the information available on the type of protein (for example, good whey protein versus good casein protein or good pea-based protein (yes, it exists) won't make the biggest difference in the world, so choose what you like best.