Proteins are basic elements in all somatic cells (nerves, sensory organs, muscles, cartilages, bones, chords, bands, skin, and the immune and hormone systems). Proteins participate in all biochemical processes in the body as enzymes and hormone components. They also ensure the transportation of oxygen and nutrients. In German, the common term for protein is the same word as for egg white.

Proteins are a major source of nitrogen and sulphur, which are not found in other main sources of nutrients, such as carbohydrates and fats. Fat can also be made from carbohydrates that are supplied with food. Likewise, carbohydrates can be synthesised from proteins. Body proteins can, however, only be made by ingested proteins.

The building blocks of proteins are amino acids. Proteins consist of more than 100 amino acids. A chain of less than 100 amino acids is known as peptides (di-, oligo- and polypeptides). According to current estimations, our body possesses about 50,000 different proteins. These consist of 22 different amino acids, in different sequences.

Of these amino acids, 8 are essential. This means that our body cannot manufacture them itself. Essential amino acids are isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine. Histidine is a half-essential amino acid. The adult body can supply a lack of histidine for a short period. For children, however, it is an essential amino acid. The more essential amino acids a protein has, the higher its value.

Biological value (BV) gauges the efficiency with which a food protein can be incorporated into the proteins in the human body. The protein of a whole egg, whose biological value has been determined as 100, can be used as a reference.

The protein content of chocolate rises with the more milk it contains. The biological value of protein in chocolate also clearly increases with the addition of more milk. Apart from the 22 amino acids that build proteins, there are other compounds derived from amino acids that have physiological effects. Cocoa also contains, among other things, representatives of the N-phenylpropenoyl-L-amino acids, which possess health-promoting and anti-inflammatory properties.