Whey protein is a component of milk protein, with the other being casein. Whey may be healthier than other forms of protein. The benefits of whey are due to the protein itself, while casein may be a better muscle builder.
Whey protein is one of the two proteins found in milk, with the other being casein. When a coagulant (usually renin) is added to milk, the curds (casein) and whey separate. Whey protein is the water-soluble part of milk.
Whey is used as a protein supplement. It is very useful for hitting targeted daily protein goals. Whey is absorbed faster than other forms of protein, which means it also increases muscle protein synthesis used to break a fasted state.
Whey also delivers a large amount of the amino acid L-cysteine, which can alleviate deficiencies that occur during aging and diabetes, as well as other conditions. While whey has also been claimed to increase fat loss, this is a function of protein, rather than the whey itself. This means that the whey itself does not reduce fat, but taking in more protein often aids with fat loss efforts.
Whey does not harm the liver or kidneys, but it can exacerbate pre-existing damage. People with damaged livers or kidneys should exercise caution when increasing protein intake quickly without the guidance of a doctor.