Whey is the liquid part that remains from the process of making cheese after the casein has been extracted. With whey you can make ricotta, or use it to extract the proteins contained in it. Whey protein powder is a very common supplement because it has some benefits. First of all, the whey protein portion includes mainly beta-lacto globulins, alpha-lactalbumin, albumin serum and immunoglobulins. These elements make it different from egg proteins, caseins and soy proteins, and the amino acid profile is also different. In fact, whey proteins are the richest in essential amino acids, and in particular in L-Leucine, branched amino acids (BCAA) which are most involved in protein synthesis. In addition, milk serum is the main source of the lactoferrin protein, known for its anti-microbial and anti-viral properties (Wakabayashi et al., J Infect Chemoter, 2014) as well as for the immune system (Kuhara et al., J Interferon Cytokine Res, 2006). Whey Proteins are very digestible and leave the stomach faster than other types of protein, and are therefore also called "fast proteins". For this reason, they are one of the best proteins to take for post-workout recovery, as that is the time when muscle tissue is most active in rebuilding its own proteins (Devries & Philips, J Food Sci, 2015). Various types of whey protein exist on the market. They differ mainly based on the protein percentage. Clearly, the higher this is, the lower the amount of carbohydrates (lactose) in the product. In some specific whey proteins may also undergo a "hydrolysis" process, through which specific enzymes partially break the bonds between the various amino acids resulting in the protein segmentation into di- and tripeptides, i.e. they are split into smaller pieces. What follows is a further improvement in digestibility and increased absorption speed.