Milk proteins: precursors of bioactive peptides

The sub-group of endogenous opioid peptides known as enkephalins was first isolated in 1975. Shortly afterwards, in 1979, peptides derived from the partial enzymatic digestion of bovine casein were shown to have opioid activity. Since then bioactive peptides derived from bovine and human milk proteins and some vegetable proteins have been detected. These findings have introduced a new criterion for defining the nutritive value of food proteins: peptides that are inactive within the protein sequence can be released during digestion, and may have hormone-like activity. Some interesting dietary and pharmaceutical applications of this discovery are indicated for the future.